Engine Management Computer

Last updated: March 29, 2000

Computer - How It Works

This is meant to be a VERY brief and simplified explanation of how the computer works, not an exhaustive dissertation on fuel injection. There are some very good ones out there. This discussion will focus solely on the engine management aspect of the computer also, i.e.- no cruise control info. Also, this applies to the stock ECU, not sure if the aftermarket computers operate the same way.

The computer has a pre-programmed "map" of what it should be doing in terms of fuel injection for given levels of RPM, load, etc. If the computer is supplying fuel to the engine based on these maps, it is operating in what is know as open loop mode. This is the simplest mode of operation. It is also not the most efficient.

Closed loop is, as the name would imply, a feedback loop. The O2 sensor feeds information back to the computer, which then adjusts fuel injection based on the information it receives. The ASCII art below shows the feedback loop:

	----> Computer ----> Intake --> Combustion Chamber --> Exhaust ----> O2 Sensor ---->
	          ^                                                                      |
	          |                                                                      |
	          |                                                                      |
	          |                                                                      |

Closed loop mode is used most of the time for normal operation. In closed loop mode, the computer uses the feedback from the O2 sensor to determine mixture. The ideal mixture is assumed to be 14.7 parts air to one part fuel. The 14.7:1 ratio will supply 14.7 pounds of air for each 1 pound of fuel.

At full throttle, the computer will drop into open loop mode (not using the feedback from the O2 sensor). This is done to ensure that the engine will be supplied with enough fuel so it doesn't lean out and experience detonation. The maps used for open loop mode typically assume that the mixture should be extra rich to prevent detonation. Open loop mode is also used during engine warmup since the O2 sensor may not yet be warmed up and won't be feeding back correct information.

The stock RX-7 computer includes other sensors in addition to the O2 sensor. It includes a knock sensor. The knock sensor listens for detonation. If the computer detects detonation, it can take appropriate action (I am not sure if the RX-7's ECU increases fuel, retards spark, or takes a different action).

Detonation is defined as the improper burning of fuel, usually caused by premature or uneven combustion. These are literally explosions in the combustion chamber. Over time, knocking will break the apex seals or other components. (Actually, the rotary engine is very susceptible to damage from detonation. Any at all will hurt the engine.) The stock knock sensor is not considered to work very well and does not seem able to combat knock if the owner does much (or any) modification to the engine (e.g.- much more than intake and catback - see the Stages page for more info on the safe order in which to upgrade). The J&S Knock Sensor is one popular aftermarket solution that a lot of people consider to be an engine-saver.

Using high octane gas may not do much for "regular" engines, but high performance engines can benefit from high octane gas since it is more resistant to knock than lower octane gas is. (According to an article I read in Car and Driver octane is defined as resistance to knock.) The way that this works is that with higher octane gas, there will be less knocking, so the computer will not have to retard timing (which would lower performance), or increase fuel (lowering mileage).

The computer also monitors other sensors on the engine, such as temperature at various locations. It uses all of the inputs above to determine how best to control the engine.

I have gotten a lot of good feedback on this, and corrected a few things. My goal in putting it together was to provide a relatively easy to understand explanation of how the computer does its job. For more in-depth technical info, read on:


From: "Ulen, Robert S" (robert.s.ulen@boeing.com)
Date: Jan 12, 2000

The stoichiometric (theoretical ideal complete combustion) ratio of air to fuel is 14.7 parts air for each 1 part of fuel by mass. Since mass and weight are the same values in Earth gravity, you could just say "pounds" instead of mass, but technically it is mass (ie, lbm, or kg). This is a well known fact that I have read in many technical engineering books.

"The 14.7:1 ratio will supply 14.7 pounds of air for each 1 pound of fuel."

In other words, if you took 14.7 pounds of air, and made it combust with 1 pound of gasoline (and I might add that the 14.7:1 ratio is for gasoline *only*), and the combustion process was ideal, then all the oxygen (and thats only the component in the air that reacts with the gasoline) will react with all the hydrocarbons in the gasoline. Hope this helps. Let me know if you need more info.


From: XBeteNoirX@aol.com
Date: November 24, 1999

I enjoyed reading your combustion article. It was well researched but not quite as correct as it could have been had engineering sources rather than marketing sources been used. Nonetheless, it is very useful for the amatuer tuner.

A few points to consider.

Except for detonation (it is the proper engineering term, knock is a mechanics term) combustion is a conflageration or controlled burn. Preignition refers to a burn initiated too early with respect to spark plug firing angle. But preignition can also occur due to chamber hot spots (such as carbon deposits) which do not actually ignite the fuel mixture but do accelerate the burn rate. This has the effect of causing peak combustion pressure to occur at too early a crankshaft angle.

Most oxygen sensors sold for automotive use act as a rich/lean switch to signal the engine management system. However, BoschMotorsport has developed a broad band oxygen sensor which produces a curvilinear output signal across the rich range. It is often used in race cars in a closed loop mode at a preset rich setting.

EGT readings bear almost no relation to actual combustion temperatures which may be as high as 4750F. The exhaust gas consists of a bung of hot gases passing across the probe during the exhaust blowdown period once every 720 crankshaft degrees. Combustion temperature will increase as the mixture is enriched from a/f 14.7 up to approx 12.0. Above that ratio the flame temperature remains constant. However, the crank angle at which combustion occurs can be changed as well as the burn angle so that the temperature in the exhaust may vary. It may also vary with load and engine speed. In fact, EGT is only valid at a constant RPM and load point such as found in aircraft engines and diesels.

EGTs used in conjunction with spark Plug Seat Temperature (PST) which is often mistakenly called Cylinder Head Temperature (CHT), can be very useful to determine the nature of the combustion process. If PST goes up while EGT goes down, preigntion is probable. If PST goes down while EGT goes up, retarded ignition or misfires are probable. If both go down, the throttle is partially closed. If both go up, full load and speed are indicated.

Knock sensors are available either as broadband or attenuated types. The broadband sensors will pick up a broad range of vibrations which may not be limited to knock. The attenuated sensors will react only to the fundamental knock frequency (5KHz to 7KHz) which has been selected for a specific engine.

When several of the devices listed above are used together, it is possible to get a good picture of the actions inside the combustion chamber. There are still some conditions which can cause problems. Suppose high octane race gas is used but the engine suffers from preignition (which is not controlled by octane) or over advanced timing. Peak combustion pressure would occur at an early crank angle and destroy the connecting rod, rod bearings and damage the piston crown (meltdown).

While fuel is metered by volume, combustion reactants are determined by mass. Inducted air will have a variable density based on temperature and atmospheric pressure. The compostion of the fuel and the specific gravity will combine to produce an enrichment index which is seldon known by the tuner. Using air/fuel ratios is almost always a problem. When a brand or batch of fuel is changed the mixture settings are no longer valid even if the jetting or injection delivery has not changed. Better by far to use Lambda (air/fuel ratio) or Phi (fuel/air ratio) measured by an oxygen sensor, as a measure of fuel enrichment.

Perhaps one of the most valuable tools to come along in recent years to assist the amatuer tuner is the use of on-board data collection. This allows several sensor inputs to be recorded and evaluated in relation to throttle position and RPM. It has become a standard protocol during dyno testing as well as track testing.

If you have any questions, I'll try to help.

H. David Redszus
Precision Automotive Research
Technical field support
Phillips 66 racing fuels


Date: Thu, 15 Jun 2000 16:09:21 -0400
From: "Sandy Linthicum" (sandy-linthicum@nc.rr.com)

>A few comments on the boost control system.
>In the 93 Service Highlights Manual, page F-25, it briefly shows
>how the boost control system operates.  Its not clear on how much
>of the control is fixed maps and how much is algorithm, but I'll
>give Sandy credit that it probably applies an algorithm to a fixed
>map.  It does show the MAP sensor input as being used for
>what the schematic calls "feedback duty signal".  So the MAP is
>used to correct the maps based on actual measured manifold
>absolute pressure in the intake system.  It is tricky talking about
>this stuff, because terminology used between people can confuse
>the whole issue.

Turbo car fuel and ignition map matrix's (one for each) are driven by MAP value on one axis and rpm on the other. For fuel, each cell in the spreadsheet/map represents duty cycle of the injectors. For ignition it represents the ignition advance. ALL other data simply adjusts this cell value for current conditions. Anyone who has worked with EFI, Haltech or Motec knows this (no flame please, Mazda does the best it can to make all this a mystery).

Using TPS instead of MAP doesn't work with turbo cars (many have tried) but is the standard for NA. TPS is simply one of the inputs that modify "mapped" operation.

In closed loop, the cell value is used as a initial value and is thereafter continiously varied to try and get the best efficency & least emmissions using the O2 sensor data. The value output by std & wide band O2 sensor is 1/2 second or more behind what's actually happening in the engine - this is the reason you cannot safely use it when on the power hard (you will go lean & blow the engine). Anyone really interested in these basic engineering relationships can download either the Motec or Haltech engine control SW demo (full function).

What most people (including me initially) do not realize is the 1000's of hours of development represented by the stock ECU pgm in regards to integration, safety and driveability. Next to impossible to duplicate in complete OEM ecu replacement. Easy to get the performance at full power, much, much harder to get daily drivability & accessory integration. This is why many who do Halteck/Motec type mods retain the factory ecu for these sub functions.

Computer Discussion

One common question is "How many mods can I do before I need to upgrade the computer?". The question has to do with what you can do to the car before it starts to run lean and experiences detonation, which will kill a rotary. Mods that improve airflow start to become dangerous if they let it flow too freely, and the stock computer does not provide enough fuel to go along with the extra air. Since the stock computer uses static maps, it either needs to be reprogrammed (see M2 Performance, Pettit, XS). See below for more info --Editor

Date: Mon, 14 Aug 2000 13:21:36 -0700 (PDT) From: e s (rx712psi@yahoo.com)
Subject: Re:(rx7) [3] Intake, DP, CB and no ECU upgrade? LONG!

I'm going to throw some numbers out on to this thread. I know its been cover MANY times, but I have never seen numbers other than my own readings so here goes.

My mods probably wont directly relate to anyone else since everyone does the catback before a midpipe, but I figure the midpipe will make a bigger deference than the catback, & considering I was only running about 8-8.5PSI on the secondary turbo the "intake, DP, CB" configuration at 10 PSI will probably be equal if not worse than my config.

Disclaimer: These are rough measurements taken with a very high quality Fluke 87 volt meter on a very low quality Bosch O2 sensor, & an Autometer boost gauge.

OK, Once I had the intake + DP config I came real close to overboosting one cold morning so I installed a needle valve into the wastegate actuator pressure line. This left me with 10PSI pri, & 8-8.5PSI sec. (don't ask me why, but the Profec B seems to have fixed it)

My maincat clogged so I installed a midpipe, & figure that with only 8PSI on the second turbo that I'd be pretty safe,

Well I did runs with the intake + DP, & measured around .97x, but as the RPM rised above 6K the O2 voltage would drop down to about .927ish I figured that to be plenty safe.

After installing the midpipe, I was measureing the .97v. (around 3K on the tach) but at 5K with 8PSI the voltage would drop down under .9v. With it going as low as .81-.80v. by 6.5K.

That is when I decided that I wouldn't run over 4-4.5K until my Power FC arrives, in fact I rarely drive the car right now.

So that is proof (kinda) that 3 mods with no fuel mods other then a K&N fuel filter, & no stock filter make the FD R-REX run lean.


To summarize, there seem to be two approaches to engine management computers. One is to have separate components (computers) for things like boost control, fuel control, etc. HKS and Greddy take this approach.

The Electromotive and other high-end computers take the other approach by combining all of these functions in one unit. This approach is preferred by the guys who are doing heavy mods to their cars.

Also, the computers can be split according to whether they are stand-alone or piggyback. (Piggyback meaning that the stock computer remains in place, and the other computers that are piggybacked on modulate the signals going into/coming out of the stock computer.) The PFS is an all-in-one unit that piggybacks on the stock computer. The rest of the high-end computers are stand-alone, and eliminate the need for the stock computer, at least for engine management purposes. The stock computer still needs to be retained for such things as air conditioning, etc. --Steve


Regarding engine control and management, it seems like most people will do something like the following (and I am REALLY guessing at some of these numbers):

	ECU reprogram		$700 (or PMC $1500)
	J&S knock sensor	$500
	Boost controller	$400
	Crane HI-6		$300
	TOTAL			$1900 - 2800

I think you can get an Electromotive for about $2500 that does all of these functions (not sure if there are additional options required but not included in this price, or if this was for a unit that would even work in our cars).

Has anyone done a cost comparison like this? I will probably be doing this over the winter or next spring and thought I would see if anyone has looked at pricing yet for a complete engine management system.

The individual component route seems like it might be a little easier to install, but you would get a lot better total solution from the Electromotive.

Note: since posting this, someone said that the PMC has boost control built in. I changed the cost numbers to reflect this. --Steve


Shiv writes about buying engine computers from people who are running cut-rate parts businesses from their dorm rooms. I changed the name to protect the innocent, and filled in the names of the "real" tuners since people may not have known who Ray (SR) and Brian (M2)are. --Steve


Date: Tue, 28 Mar 2000 10:54:02 -0800
From: "Shiv Pathak" (shivp@worldnet.att.net)

No offense, but where did [vendor] learn how to create baseline ignition maps? Through trial-and-error like SR Motorsports, Mostly Mazda, etc,. Or did he copy the maps from someone them? To me, A product such as this is only as important as its after-sale support. Not only must the support be generous, but it must also be knowledgeable. Especially when you're trying to tune an engine as fragile as ours.

Come on guys... this market is small. Let's do our best to support those who have done their part to advance the state of the art. This means buying from the real tuners. You know, the guys who use the money they make in the aftermarket to race and then, in return, develop new products. It's really sad when these hard-working guys chose not to develop and market an otherwise brilliant product just because they fear it will get copied a couple of months later and sold out of someone's basement. I've seen it happen too many times. Sorry for the rant...


Date: Thu, 20 Apr 2000 01:51:52 -0400
From: Wael El-Dasher (wael.el-dasher@efini.net)
Subject: Re: (rx7) [3] 850cc installed in primary rail and other questions

M2 educated me about the fuel system a few days ago when we were discussing a setup for my car. (snip)

I have a fuel pressure gauge in my car so I am able to monitor it (with peak hold) while driving and set it up accordingly. I was considering using larger injectors, but the EFI PFS/RUN DMC/PMS PMC can't varry the ratio of primary and secondary injectors like the MoTeC can, so the stock ratio must be maintained.

With M2's current MoTeC with harness & sequential turbo operation/oil metering for less than $4k, I would consider it. But the reality is I do not need it for my use of the car (street use/occasional track days). Unless one moves to a MoTeC that gives you that level of control, sticking to the stock injectors is the only option as several members had terrible luck with boring out injectors. I remember Westbrook, Chuck wrote at length on this subject a while back and methodically explained the steps to maintaining the ratio when using larger injectors. I can not remember if the injector sizes he recommended were bored out or not. Can the RP-Online Haltech E6K or the SR Motorsports Apex-i Power FC with Commander (I hate long names, so I mock them whenever I can) control the ratio like the M2 Performance MoTeC M4? Just curious...


From: Tuck
Date: Mon, 23 Dec 1996 23:59:20 -0500

At 12:20 AM 12/23/96 -0800, NetBlazer wrote:

>>That is one of the reasons why the PFS computer is
>>capable of some self-programming.  The computer can read from the MAP sensor
>>and see that the desired amount of boost is being exceeded or not being
>>reached (no cats or partially plugged cats).  It will then experimentally
>>tweak the wastegate control until things are running properly.  That
>>variation between otherwise identical cars can explain why a computer like
>>the PFS one might be dialed in perfectly for one and not for another, 
>Exactly, but what happens when you finially decide you don't like sequential
>twin turbos, and don't like troubleshooting all those hoses which periodically

Personally, I'd like to stick with the sequential setup. No reason I can think of why you couldn't teach the PFS rig (either of them) to control boost on the non-sequential setup.

>crack and or pop off (I know replace them all with silicon hoses).

Gotta love that bright yellow silicon hose!

>go non-sequential you will be glad to have an aftermarket boost controller.
>Most of the ones made today have a learning mode similar to whats described 

That's true, but a simple price comparison makes it obvious why the PFS is even a price/performance leader. Sure you can just stick a damn stopcock in to bleed off pressure and set a peak boost level, but if you want real control you need something like the HKS EVC. The price of the PFS computer, which controls boost, ignition and fuel is less than an F-Con and an EVC, and the F-con and EVC aren't nearly as programmable anyway (The F-con just has that little 5 position global adjust as I recall). I suppose if you really wanted to run oodles and oodles of boost then the EVC would be a worthwhile companion to the PFS computer. The reason the EVC is so good at what it does is that it is a fairly expensive stepper motor rather than a simple duty valve like the stock unit.

>>First I'll have to define a few terms.  It was recently argued by my best
>>friend Kevin that the third generation cars only have one wastegate to
>>control boost.  This is not correct.  The factory service manual does not
>>describe it as such (instead calling it a control valve or some such crap)
>>but aside from the wastegate on the second turbo, the gate that dumps
>>exhaust into the second turbo to spool it up also acts as a wastegate for
>>the primary turbo.  It has it's own duty valve to control the gate actuator,
>>which determines how much boost is generated on the primary turbo just like
>>the wastegate on the secondary turbo.  The way the wastegate is controlled
>>is via a sort of arm, and that arm is in turn manipulated by a normal
>>wastegate actuator.  
>A waste-gate typically dumps exhaust to the other side of the turbine(s) 
>and out the tailpipe. For it to be a waste gate it must be allowing gases 

Typically, yes.

>to leave the system. The Turbo Control and Turbo Pre-control gates do not 
>allow any exhaust to bypass the turbines. True changes in these two gates 

While that is true, the thing DOES act as a wastegate in that it is used to control boost on the primary turbo. In that respect it can be treated as a wastegate. I think the appelation is accurate.

>changes how much exhaust from the rear rotor gets to the front turbo, but 
>it doesn't leave the system, it just redirects it to spin the secondary 
>turbo which is part of this system and is creating boost at the rpm where 
>the turbo control gate opens.
>On a side note the waste gate on my car (primary turbo turbine bypass gate 
>which is the only true wastegate on the twin turbo setup) Does an excellent 
>job preventing any boost spiking with an aftermarket EVC with its own large 
>solenoid. As for the other gates my car was setup several different ways: 

Of course, something like the EVC can dump vastly higher quantities of air than the stock duty valve, so it won't need a smaller restrictor in the pressure line, and as a result the reaction time will stay high enough that you won't get boost spiking. BUT an EVC is how much? 900 bucks as I recall (and no fuel or ignition control of course), making it damned expensive unless you really want to run uber-boost (and keep in mind that the newer PFS computer is perfectly capable of handling significantly higher boost levels because it can control both duty valves...). It is a tradeoff really. With something like the PFS computer you just stick in a few plugs and you never need to get under the car and screw around with anything. To install something like the EVC you have to get under the hood and screw around with the vacuum lines.

>First it came to me with the EVC controlling the turbo pre-control gate and 
>primary turbo wastegate as if they were both waste-gates. This resulted in 
>exagerated lag when the secondary turbo was brought online, but never ANY 
>boost spikes that showed up on a boost gauge.

Like I said, with the stock restrictor pill thing the reaction time of the wastegate stays high enough that boost spikes cannot occur.

>Second I set it up non-sequential with the turbo control and turbo pre-control 
>gates completly removed, and the waste-gate actuator hooked up to the EVC. 
>Still no spikes, stayed rock solid at preset levels to redline (usually 1 bar)
>This however did not prevent my stock computer from exercising a fuel cut which 
>cost me the rear rotor. (HKS FCD is only rated for 14PSI and I don't reccomend 
>exceeding this for extended periods of time, or high load (5th gear at 150MPH 
>in my case))

Interesting thing is that the stock computer has fuel maps all the way up to 13psi and above. The reason you can't go higher of course is that the fuel cut to the rear rotor kicks in as soon as it sees more than 11 psi for more than one second from the MAP sensor. You put a voltage clamp on the map sensor so the computer never sees over 10 psi and you're set, except of course that you still can't get at the maps for higher boost levels. The way the Tectom rig works is by sort of bubble gumming around the main processor. You remove the stock processor with the fuel maps and the boost cut on it and solder it into a daughterboard. That daughter board has eprom sockets that you stick your custom-burned maps into, and basically what they did was they sort of cracked the proc with the fuel maps and boost cut on it. They trick it into looking at those eproms instead of the internal stuff. That's why it keeps the original chip. Neat, but too complex for my taste.

>The above two examples proves (to me at least) that boost spikes can be 
>completly controlled using an aftermarket EVC, and only the single wastegate 
>on the turbos. This indicates that the stock wastegate/actuator can do a very 

That's true, but aside from something like a motec or electromotive or a similar such unit, you're still going to have to deal with fuel and ignition maps with the PFS rig. Might as well just get the newer PFS computer and use that, you'll still get your really high boost levels and you get it all in one simple package. The other advantage is that if you DON'T want to screw with it, it can reprogram itself to your machine, and if you want to fine tune it you can get the keypad and do it. From a marketing perspective it's a really trick box.

>good job of controlling boost spikes but the stock solenoid/restrictors as 
>described below by Tuck (if his info is correct) is not able to do its job 

Again, with the purple computer you do not need to change the restrictors, and you only had to do it with the gold one if you wanted to exceed the design specs on the unit. Keep in mind that the gold computer was designed to be a part of a STREET LEGAL (50 state) performance package, so it was assumed that the cats would stay on the car. Within that specification, the unit worked flawlessly because the limits of that one duty valve and the restriction of the cats prevented you from going significantly higher.

>properly and needs help by tweaking with the turbo control and pre-control 
>gates which should not be messed with IMO since they are doing a completly 
>different job which has its own timing issues, and were not designed for 
>the purpose of controlling boost spikes.

This is not correct. The valves that you refuse to call wastegates are used by the stock ecu to control boost on the primary turbo. That is part of what they are designed for. Of course you are correct that that same system is used to prespool the secondary turbo in the stock sequential setup.

>I still say lose the stock mess and go with a Purpose designed unit that 
>can spend 100% of its time doing its job. And if you rip out the cats 

Well that's your pervue, but in terms of technical sophistication and programmability the PFS purple box beats the EVC hands down. While the EVC will allow you to program a boost curve of sorts, it doesn't give you 1/10th of the resolution that teh PFS computer(s) do. The real thing you are paying for with the EVC is the expensive stepper motor/valve. You could just as easily replace the stock duty valves with something that can flow more, say the duty valves from a grand national (about 50 bucks or so each), and use the pfs computer to control that. The purple box of course is capable of controlling boost beyond the capabilities of the stock fuel system, so I'm not sure why you'd want to.

>non-sequential operation is the next logical step since the only reason 
>for sequential was the exhaust restrictions imposed by the cats / stock 

The sequential oepration is also designed to provide boost as low in the rev band as possible. Whether or not anyone wants to admit it, going to nonsequential might free things up a bit at the top end, but it simply must increase the time it takes the turbos to spool up initially. Since you can easily get over 15psi at the top of the rev band without switching to non-sequential, I can't think of any reason to reduce drivability (however slightly) for what is probably a minor gain at best.


A knock sensor is an almost indispensible item for a rotary if you are going to modify it. One note - if you buy a high-end computer, it will probably include a knock sensor, so you will not need to buy a separate one (I am pretty certain the Electromotive does, and am guessing the Motec does too). --Steve


Date: Fri, 17 Sep 1999 17:58:58 +0000
From: "David Lane" (dlane@peabody.jhu.edu)

I believe one of the keys to the puzzle is the variability of where our cars are, and how they are used.

For instance:

Some of us live where we can get 94 octane pump gas. Others are limited to 92 octane, and some formulations are better than others.

Some of our cars have to cope with sub-freezing temperatures. Others stay in the balmy zone all year around.

Some of our cars have early ECUs which, if I read the list correctly, behave differently than the later ones.

Under given circumstances, some of our cars will show boost creep. Others won't.

Some of our boost gauges are not as accurate as others, and may be reading a PSI up or down.

Some of our cars are modified for the occasional street romp. Others are set up for the strip--some for road race tracks, others for autocrossing. Then there are the cars that are hardly revved above 5k, owned by people who just love them because they feel and look great.

So, a given set of modifications which will cause no trouble on a 94 octane car, located in the South, and never used for competition will be disastrous on a machine run hard in freezing weather at the track with 92 octane fuel.

While you may want to argue the technicalities of it all, the bottom line is that the only way anyone can assure someone else that suggested modifications will be safe is to stay very conservative. In my report on Mostly Mazda last year, I mentioned to Brian that one of his customers was using an M2 chip at higher boost than recommended--and was very happy with it. Brian said his chips were all set up for 92 octane California fuel, and that they had a lot of richness built into the maps. We can just call it "head room." Advocates of user programmable ECU upgrades like the PFS unit don't like the added richness (slows them down), so they prefer to tune their own maps, usually with less headroom. Those who install fully programmable units like the Electomotive say that for cars in my area (100 plus temps in the Summer with rare plunges to 0 F in the Winter, picky owners develop four different map sets; one for each season.

So, what's "safe?" Maybe a better question is, "What is your tolerance for risk?" Mazda delivers the car to you with enough headroom to hopefully be able to cope with all of the variables listed above at 10 psi max boost. If you are modifying the car to produce significantly more power, you are not really safe unless you duplicate the headroom Mazda built in--albeit at a higher boost level. That's why Brian wants you to get an ECU upgrade with just an intake and catback. The other reason is that he says he has figured a way to work around the stock boost control limitations, so that when you start working your way up the modification/power ladder, you won't deal with boost creep. Note that I mention the M2 upgrade sequence simply because I have not talked to Cam about his ECU, and of course Peter uses a programmable unit. Nevertheless, it may be (just guessing here) that cars with the M2 chips just happen to not be the ones with the boost creep problems.

In the end, if you have a high tolerance for risk, and use your car only within certain boundaries, you may be able to get away with less headroom in the system. However, if you don't have such a high tolerance for risk, you absolutely must maintain as much headroom as you can--just in case the day after you filled the tank with 92 octane the temperature hits a record low and some guy in a hopped up Mustang doesn't want to give up until you are going over 140 mph.


Date: Thu, 10 Feb 2000 23:35:17 -0800
From: Max Cooper (max@maxcooper.com)

> Are the stock fuel maps good up to 15 psi if you remove fuel cut?

No. You can't reasonably remove the fuel cut without limiting the boost the computer sees, so you are asking if the computer's 12 psi maps are good for 15 psi. No, they aren't. And if you have increased the flow capacity of the intake and exhaust, they might not even be adequate at 12 psi (my car detonated at this pressure with the stock main cat and computer, using an upgraded intake, ic, dp, and cat-back above 4500 RPM).

The stock ECU is tuned for the flow characteristics of the stock intake and exhaust. Unlike the more common mass-air control systems, the [3]'s speed density system CANNOT adjust for a better flowing intake, intercooler, or exhaust. Mass-air systems have a flapper door or other means of measuring the amount of air the engine ingests and provides fuel based on that measurement. On the speed-density system of the [3], no such measurement is made. Instead, the computer reads the engine speed (RPMs) and air density (its temp and pressure) and delivers fuel according to a map that was programmed based on the stock intake and exhaust systems. Those maps are no longer valid when you change the flow characteristics of the intake and exhaust systems. Some people have argued on this list that the air that flows through the engine is simply a function of boost pressure; that 10 psi before mods makes the engine flow the same as 10 psi after the mods. This is simply not true. For simple evidence, consider that the reduced back pressure of the exhaust system will leave less exhaust gas in the combustion chamber and that leaves more room for fresh air and thus a need for more fuel. Got it? The modded engine flows more air and thus needs more fuel. The computer knows only about engine speed and air density - nothing about flow so it can't compensate for these mods. The fact that you can run some mods is only because they don't take the engine out of the rich safety zone built into the stock fuel maps. Of course, it does put you closer to the edge, and eventually over the edge if you add enough mods, or the air is cool enough, or you get some bad gas, ...

It is foolish to run a lot of mods with the stock fuel maps. You won't get the power you are looking for and will spend more on an engine rebuild than you would spend if you did the right thing and got a computer to match your mods in the first place. A lot more -- don't do it.


Date: Wed, 12 Apr 2000 17:26:23 -0400
From: "\(Mr\) Sandy Linthicum" (sandy-linthicum@nc.rr.com)

Doesn't matter what CPU you use, 1/2 second distance from real time control in closed loop will cause you to go lean and detonation in race/track conditions. Its true for the Motec as well as any other engine computer.

You may be implying using O2 readings to adjust fixed maps - which is fine. Running real closed loop means you ajust fuel, etc. based on the O2 sensor data (this is the major controlling factor). In WOT conditions you cannot afford to be 1/2 second behind.

The Motec allows you to configure the closed loop operation by rpm & load (map sensor) and typically you exit closed loop if Map or RPM show hard use.


Date: Fri, 14 Jan 2000 10:51:50 -0700
From: "Owens, Shaun" (ShaunOwens@aec.ca)

Here's a link to an old (October 1997) review of various stand-alone EFI systems. It doesn't appear to have any contact info for the vendors of the EMS system, but there's a little info on each of the systems. http://www.geocities.com/MotorCity/Garage/1043/EFIreview.htm


Date: Wed, 22 Mar 2000 15:00:17 -0800
From: Dave (evadf@hotmail.com)

I just wanted to let you know that I got my Power FC from SR Motorsports. I installed it this weekend and it works great. I am very surprised of how easy it was to install. This thing is great. I would take this over a chipped computer any day. It gives me all sorts of information. This like having a fully programmable fuel injection system with out the headaches.

I tried the EFI unit, a Chipped computer, HK$ VPC and GCC, Tec II, and a Haltech in the past. I think with all of those units, I know what I am talking about.

All of those units works fine and did make my car go fast, but cost me a lot of time and headaches.......

The VPC was good, but in my opinion is not made for Rotaries. There is not way it could handle anything over 11lbs of boost. ~$800

A Chip was also easy to install, but you have no adjustability. If you upgrade something motor wise (ie. intercooler, turbo etc..) the mapping WILL be off and will not work to it's full potential.

The Tech II is good, but will take a very experienced tuner to get it tuned right for daily driving. It took me 2 years to get the car to be everyday driveable. I am sure someone like Ray at SR Motorsports can do it a lot faster though. I was impressed by the effects of the unit though. I think this was the key that made my case into the 11's. When I had it, it did not have staged injection. Ray tells me now they do. ~$2300 without injectors and software.

Haltech is a good unit, but I did not get to full around with it long enough. It gave me some timing problems that I never did figure out, but worked well with the rotaries. ~$1800

I think after all that I went through I am glad that I meet Ray at SR Motorsports. He introduce me to the Apex~i Power FC a few months ago and told me about the features, but I was not too impressed until I saw it work in his car. I don't care what anyone says, but the Fuel Injection WILL be or IS the key to making a Rotary Car fast and reliable. I have rebuilt many engines to know what not to do now.

I did not get a chance to run the car a lot, but from what I have experienced I think this would be the way to go. It was easy to install, and you don't have to do much to tune it. Ray had set a base map in it for me and it was very close to what I have. I will be putting in a single turbo in my car later, so I am sure I will have a lot of tuning to do after that. From what I see of the unit I am sure it will handle it. I just need to upgrade my injectors.

My current mods are as listed:

SR CAT back
SR Mid pipe
SR Downpipe
Vacuum lines tied off
SR Intercooler Upgrade
SR Intercooler Pipes
SR Air box
SR Air Pipes
SR Race Plugs
Apex~i Power FC
Apex~i AVC-R
SR Fuel Pump
SR Fuel Pressure Regulator
SR Pulleys
ACT Clutch
SR Flywheel
SR Radiator

My advice:
For what it is worth, to all the newbies on a rotary engine the best and first upgrade should be the computer. Everyone is always going to get the exhaust and intake first, then what? I have rebuilt 3 cars now where they bought an exhaust and intake, they blew up their motors. The computer will be the determining factor if you are going to blow a motor or not. Bang for the dollar get the Apex Power FC. To my knowledge SR Motorsports (925-516-7382 or ray@shaneracing.com, www.shaneracing.com)is the only one that has them right now. You can't even get it through Apex. I am glad I was informed of it last week. I went there personally to get it so that he would not run out. I know there are a lot of people who want them. I think he has a few left. Again I think this is a good bang for the dollar. Plus when you are not at the race track (hint, hint) you can always plug your stock computer back and get your smog check done.

After the computer then you could get your exhaust, intake, fuel pump, regulator, clutch and flywheel, intercooler, Radiator, pulleys, then single turbo if you want. I would suggest you get it in that order too.

Again this is only my opinion. Please do not send me flames about how wrong I am. I am just offering a suggestion to a new product out there to everyone. I do welcome real performance questions and not one where you are going to debate if the color of a pulley will make your car faster. Email me at evadf@hotmail.com.

BTW I did not get to run the car after the install, but I did race my friends 300z turbo who does 12.0 in the quarter and I beat him he now wants a RX7.


Date: Wed, 19 Apr 2000 19:27:59 +0000
From: ryan.schlagheck@att.net

I am not an authority on the Haltech. I'm a satisfied consumer and wish to convey my 2cents on the matter.

Rotary Performance in Garland, Texas (www.rx7.com) has made the installation of the Haltech E6K very, very simple compared to other standalone products (like Motec and Wolf3D for instance.

Motec is either straight gotting of the FD harness and replace with Motec's harness, or go via M2 Performance route and run the stock harness tothe Motec (congrats to Brian Richards for sorting that out).

The Wolf3D requires a different crank trigger wheel, add $ for the parts and fabbing of bracket - and it better be perfect or else you'll start all over again.

The biggest advantage in my mind from an installation standpoint is the fully terminated harness that comes with the Haltech kit from RP. This is a value-add RP offers that is worth the additional $150. I paid $1627 for my complete Haltech E6K kit, which included a 3bar (~44psi) MAP sensor. Get a 3bar MAP sensor, datalogging (to fine tune yourself), and a host of optional features (no additional charge for many) including fan switch (like the FD fan mod but while running), turbo timer, shift light, correction maps, to name a few.

As I stated in a previous post, the datalogging capabilities are great to have, and some will wonder afterward how they ever got along without it (rx7 geeks?). Imagine swapping intercoolers and being able to see what the charge temps at the manifold are between the two. Imagine being able to look at your datalogs and figuring out that at a certain ambient temp at WOT, you're better off shifting sooner because your water temps get pretty high if you stay in it to 8200 rpm. Imagine being able to load maps for 116 race gas on 10.5 racing plugs for track, then load another for 93 octane w/ NGK9 platinum plugs for street, simply by loading up a map from your laptop to the ECU... Imagine that your stock wiring is more brittle now than when you did your tie-wrap job because you presuambly upped the boost and therefore heat production. The finest drop-in ECU system in the world for the FD (which I believe to be the PowerFC) can't do a thing for a fried harness.

I'm not trying to start a holy war. I've got more time invested in this car than others, but I'm not about to stand up and preach the good word...

The PowerFC is a great tool for those who don't have time to screw around with tuning, don't need datalogging, and simply want to drop-in and go.

The Haltech is for those who can take the time to tune, add premix at the gas station, and are looking for datalogging as a key value-add to a $1500+ system. There are more pros and cons than those listed above, I just touched on those that I used as my purchase criteria.

To each his or her own. I think they're both good products but like any product selection, you need to satisfy the basic criteria:

What are you going to use it for?


From: Tuck
Date: Mon, 23 Dec 1996 01:49:10 -0500

(stuff deleted by Tuck)

>so he must know what he is talking about. His stuff is a hell of a lot
>better than HKS stuff, unless of course you want to buy two or three things
>and have a lot of lights sticking out of every space in the car, instead of
>the one computer plug in Peter has.

Not only that, but the PFS computer is infinitely more adjustable than the HKS F-Con. The F-Con is a vastly less powerful unit, basically in order of adjustability and overall performance, the list sort of goes:

  1. PFS Computer (infinitely adjustable and can be done from the keypad).
  2. Tectom/Pettit chip (very adjustable but must be programmed via eproms).
  3. HKS F-Con (barely adjustable, but has fairly good built-in maps).
  4. Everything else (Trust/Greddy stuff is weak even in comparison to the F-Con - - only advantage is that the extra injectors increase maximum fuel capacity).


From: Tom Gandey
Date: Mon, 23 Dec 1996 12:00:11 -0500

How about adding MoteC and the Electromotive to the list, far above the PMC.


From: "Kevin T. Wyum"
Date: Wed, 25 Dec 1996 06:47:49 -0600

I think you forgot to mention a few that come above it on the list Tuck.

to name a few.

> PFS Computer (infinitely adjustable and can be done from the keypad).

(The PFS Computer has) 3 load points, 2 boost maps which each have 4 RPM bands for fuel and timing. 25 map points which includes the idle set. I seem to remember infinite as being a number much larger than 25.

Hehehe. Hmmmm my PFS special gold box if opened has this strange stamp on the circuit board. Uhhh It says something like Crane Cams in bright white letters. I believe all of the Gold Box boards say this. I said it was a modified Crane interceptor II. Which it is. I can't believe you're dumb enough to bring this up again. Even the new ones are not a special PFS engineered and designed computer. It's an EFI Systems PMC. EFI =3D Doug W. The guy I mentioned I have a lot of respect for. Look in any current Turbo mag and you'll see it for the Eclipse, Mustangs etc. Strange huh, looks just like that new purple computer of PFS. Gee, this all seems to make sense considering Doug used to work with Crane and to my understanding was one of the primary developers of the Interceptor. I still don't understand why you (you meaning the PFS clique) throw such a childish tantrum over this fact. Okay all knowing Justin, why is Crane cams printed on the circuit board???? Answer me that since you state above "(not true)" I guess I don't understand what the big deal is if it is a slightly changed Crane interceptor. Is it the big price markup? So what if he doubles the price. He has an exclusive on reselling it anyway. I don't see any threat to him.


From: "Kevin T. Wyum"
Date: Wed, 25 Dec 1996 06:36:58 -0600

P.S. Trev you may want to check the Haltech setup before jumping on the Motec. Save a thousand or two. Think I've scratched the Electromotive idea in favor of the Haltech now. Getting more details.


Date: Tue, 2 Mar 1999 12:44:37 -0800 (PST)
From: NetBlazer

An EFI Systems gold or purple box can be setup to work okay with larger injectors, but the drawbacks are enough to make it more worthwile to just go with a complete replacement ECU.

The most notable problem is with a piggyback system is the stock ecu will be fighting you the whole way. When you get everything dialed in perfectly, and do a KOKO everything is a little different.

Other big concern is with a piggyback computer, it needs to tap into the injector wiring and re-route it from the ECU through the semi long cable to the PMC and then back out to the injectors. Ignorning the relatively small added delay, the big concern is the added chance of a bad connection to an injector which would spell almost certain detonation if it was either intermitant, or just went bad under boost.

One other concern is the transition point where the stock ECU brings the secondary injectors online is not set in stone, and varies based on enough parameters to make it impossible to program for it properly on the PMC. It will work, but its not even close to ideal, and in my case I could not live with it.

Carlos went to some extra effort and put in larger injectors that had the same cc ratios as the stock injectors which took care of the last above concern AFAIK.

IMO the cost of a PMC with keypad and data logger is sufficiently high that when combined with even one drawback makes the electromotive or other similarly priced stand alone computer system look like a bargain...

(Editor's note: I think the PFS PMC is a piggyback unit. --Steve)


Date: Tue, 2 Mar 1999 21:15:00 -0800 (PST)
From: NetBlazer

> Piggybacks work pretty good with hardcoded and hardwired into
> the stock ECU like Pettit's, Mostly Mazda's, etc. ECU upgs.  This 
> approach also limits the ability of the user to screw up & ruin
> the engine.

When I said piggyback systems I meant ones that are externally piggybacked. The Tectom upgrade everyone on your list is using replaces the fuel maps, and removes or massages the rev limit, and fuel cut. Its piggyback is a logic mod (using PAL chips and an EPROM) at the main CPU. It also replaces the stock EPROM. Much better way to go IMO if you are on a budget. If you do want the huge amounts of power a single turbo can provide you are going to want to be able to tweak everything (meaning a stand alone ECU) as you play with A/R ratios, etc that have now become available at a *cheap* price due to using a mainstream type turbo.

I will repeat in another way...I am NOT saying you cannot use a PMC to do this, as it will work, and ultimately it is more flexible than a ROM tune, but if you are going to take the plunge into single turbo land you will be better off with a stand alone box IMO since you will probably soon be at the point where you need one anyway and then you have to deal with selling the PMC as a used item and them having to buy a new stand alone (insult to injury when you find out no-one is willing to pay anywhere near what you spent on a PMC (I know I have sold 2 of them before on this list))


Date: Sat, 18 Sep 1999 16:07:57 -1000 (HST)
From: F8LDZZ (f8ldzz@lava.net)

> Any idea why it doesn't have a mass flow (AFM) sensor? Cost? Non-linearity?
> Operating conditions range too widely?

MAP-based systems are linear.

> Seems I remember someone posting the downside to a mass sensor vs the upside
> to a pressure system and that given the operating conditions, it was a good
> trade-off. Anybody know the facts/arguments?

AFM - generally more "accurate" in terms of air flow measurement
    - replacement cost "high" - over $1000 new
    - "restrictive" versus a MAP system
    - "low tech" due to moving parts (with exception to Hall Effect)

MAP - cheaper to replace (usually <$500 for pressure sensor)
    - "high tech" due to solid-state electronics
    - "less restrictive" - MAP readings can be "calibrated" to (any)
      intake opening size


Date: Sat, 18 Sep 1999 12:47:54 -0700
From: "Michael Card" (cul8r@my-deja.com)

I've been trying to find out what the EXACT fuel cut off points are on the 93s. I have an early run edition, one of the first batches sent over from Japan, and was wondering what fuel cut points were.

According to Rob:

The ECU will cut the fuel to the rear rotor when this boost level is reached at this rpm:

1000 rpm   11.8 psi
2000       11.8
3000       12.4
4000       13.3
5000       11.3
6000       10.7
7000       10.7

The shops all told me 12 lbs was the cut off...so kinda wondering. Anyone out there know exactly how the stock chips funtion?


From: Jay (styk33@yahoo.com)
date: April14, 2000

>What happens when the computer makes the 20K mileage switch, 
>i.e.- what changes at 20K miles?

I know you inquired last week about the milage switch. If you want to see what happens to your car with it 'deactivated', try this.

Disconnect wire 1N on the ECU. Connect the ECU side of that wire to a 1.2DCV+. I am unsure of what resistance is needed on the other side. You might try getting a 12VDC zener diode from radio shack and put it inline.

If you are still curious and don't feel like playing with the ECU wires(don't blame you if you don't), call Brian at M2. He might have more info if you need it.


The PFS computer is a piggyback unit that works w/ the stock ECU. It modifies the signals coming from the stock ECU and reports back to it that everything is still alright.

It is very programmable, which is a benefit and a drawback. You have to know what you are doing. You also have to buy extra software for a PC interface, or buy a keypad to program it. Unless you have PFS install and tune it on your car.

Some people have posted that they have had success with the PFS computer. Brooks' note below is a negative one, echoed by others who have had problems. No concensus on this yet.

It is a version of the EFI computer. See the EFI section below for more info. --Steve


Date: Mon, 29 Dec 97 22:54:33 -0500
From: Brooks Weisblat

There have been many problems with PFS computers and posts on the list about them also..........i have received many private e-mails about people having problems with them...

So what you're saying is that if PFS doesn't install the computer.......it may not work right? it seems that the only people who say they have it working "perfectly" have had their car at PFS for the install.....

I personally won't believe it until i ride in a car that has it working perfectly....fuel and boost

My purple box went back to PFS 3 or 4 times, Peter even e-mailed me new software to be uploaded to the machine...........and it never worked right....and peter is the one that I talked to on the phone one or twice a week for 4 months straight....do you want to know what Peter's explanation for the box not working correctly in my car was??

And I quote "your borla exhaust is the cause for the computer not working correctly"

I also tried a 2nd hand purple box in my car.....that didn't work right either....yes i know how to program the machine......it's not hard....anyone can do it.....

Yes, I'm saying that my pre-programmed chip works MUCH BETTER than the PFS box......hands down...no question about it.....im never playing with the stupid #'s all the time.....fouling out plugs....detonating because peter said to hold the throttle down until the computer brings down the boost and learns the curve....

You can't say that my car was at fault either.....without the PFS box my car ran fine...after returning the PFS box and installing a pettit computer my car was hitting 11 second timeslips with 14-15 pounds of boost....


Date: Mon, 29 Dec 1997 23:47:00 -0500
From: Tom Gandey

Not to say that the PFS box is a P.O.S., but Brooks has proved that Cam's (Pettit) maps DO WORK, and can better anything you have produced.

To the best of my knowledge Kevin is the only one to run 11s on a gold or purple box.


Date: Thu, 3 Dec 1998 15:44:56 -0700
From: dbeale

  1. The PMC has three settings (rotary switch). It comes set for 10 PSI (stock), 12 PSI, and 14 PSI. It is set a little rich as it comes, for safety.

  2. You can change the settings whenever you want (you do need the keypad to do this).

  3. It controls boost, fuel, and ignition timing, and you can adjust all three. The boost control is very good on my car (no spikes - and I have no cats. and a 3" system with an HKS super dragger).

  4. If you get the keypad you can also monitor many engine functions (timing, fuel injector % open time, O2 reading, rich/lean reading, boost [with a GM MAP sensor you must add], and more I can't think of right now ;-).

  5. It's very easy to install - just unplug the ECU, plug the PMC into it, and plug the ECU cable into the PMC cable (it goes between the ECU and the ECU cable). It comes with a fairly long cable, so you can mount it in various places (not long enough for behind the pass. seat though, and not under the carpet like mine was when I got the car). I moved it to the trans. hump pass. side all the way forward, and as high as I could get it.

  6. If you mount it in plain view, it gives you riceboy points (shiny purple finned complex looking device). That alone must be worth, what Jim LaB., 10 HP?

I run mine at the stock setting - but I'm chicken - cluck, cluck. The car is scary enough there. It's faster than my motorcycles! Acceleration, cornering, braking, and especially top speed. I think the higher settings are pretty safe, as it runs very rich. You can get in too deep even easier though, and you do use the car up much faster (as in break parts). I need much more practice before I get there.


Date: Thu, 13 May 1999 08:10:01 -0400
From: "Karagiannis, Demetrios, Mr., ODCSINT" (Demetrios.Karagiannis@hqda.army.mil)

Peter does not have exclusive rights to the EFI box. He is a distributer just like anyone else. I bought my EFI PMS from Turbo Performance Center along with the AID (additional injector driver) TPC carrries the PMS (minus PFS sticker) and Electromotive computer for all makes and model to include the RX7.


Date: Fri, 14 May 1999 01:54:19 -0400
From: Max Cooper (m_cooper@csi.com)

It is manufactured by EFI Systems -- makers of the PMS.

PFS may have an exclusive contract to sell them. In other words, EFI may be contractually restricted from selling them directly or through other distributors. I don't know if this is the case.

The custom programming by PFS is worth something. Also important is the support you have access to if you buy the computer from PFS. I had a hard time understanding why PFS was reluctant to upgrade the units for people who bought them used until I realized that it was the support issue. When someone buys one used and gets it upgraded, they often need support in order to install and tune it. The difference in upgrade prices between original and new owners is $250, so installation support seems to cost about $250 in that context. Additional provision for ongoing support costs is probably included in the initial purchase price, though we don't have a convenient way to determine how much.

A lot of list members have a problem with shops that relabel and sell products at a premium. I think what entitles them to do this is the support and knowledge they make available to their customers. Many list members are or like to think that they are experts, so paying more for the (perhaps unneeded) tuners' knowledge is not attractive to them. Maybe the experts don't need it, but there are many who do need it, know they need it, and are willing to pay for it. I see nothing wrong with that.


Date: Mon, 29 Dec 97 22:54:33 -0500
From: Brooks Weisblat

Yes, I'm saying that my pre-programmed chip (Pettit) works MUCH BETTER than the PFS box......hands down...no question about it.....im never playing with the stupid #'s all the time.....fouling out plugs....detonating because Peter said to hold the throttle down until the computer brings down the boost and learns the curve....

You can't say that my car was at fault either.....without the PFS box my car ran fine...after returning the PFS box and installing a Pettit computer my car was hitting 11 second timeslips with 14-15 pounds of boost.


Date: Mon, 29 Dec 1997 23:47:00 -0500
From: Tom Gandey Not to say that the PFS box is a P.O.S., but Brooks has proved that Cam's (Pettit) maps DO WORK, and can better anything you have produced.

Mostly Mazda

I believe Mostly Mazda will reprogram your stock ECU from the sounds of Jim's note. --Steve

Date: Fri, 21 Nov 1997 10:30:41 -0800
From: "Jim LaBreck (ECA)"

Brian (at Mostly Mazda) said that this was easily the most drastic ECU he'd done, but it will work well for most intermediate levels of modification up to full out gutting of the intake and exhaust and non-sequential modifications, among others.

I was told that it would control boost in sequential systems without the need for a separate boost computer, but non-sequential systems will definitely need a controller, as the ECU no longer has the means to regulate the activity of the second (rear) turbo in that setup. It has fuel maps up to 22 lbs. of boost, but with systems with stock injectors, they'll reach their maximum duty cycle at about 16 p.s.i. I would not recommend going much higher without high octane fuel, an upgraded fuel system, and/or larger injectors.

The fuel maps are beautiful, by the way... something that it would take hours to achieve with a gold or purple box, plus you don't have to find a place for that extra box to live in your car, which is one reason why I chose to have my ECU reprogrammed.


HKS takes the component approach to computers. They have several:


Date: Fri, 30 Apr 1999 10:50:51 +0000
From: "David Lane"

AIC: Additional Injector Controller

I have an older model HKS AIC. In addition to setting the boost and rpm levels at which the additional injectors begin to fire, it has two other controls to specify the rate of increase for fuel flow as a function of boost and/or rpm increase. These "rate of increase" controls are linear. That is, the "curves" are straight lines. Both curves combine as both parameters increase. Obviously, the RPM trigger does not activate if the minimum boost has not been reached.

My old unit has an LED bar graph to show the percentage of available fuel being used (duty cycle). It also has lights to show when each function (RPM or BOOST) has reached the threshold. You can use this information in conjunction with your tach and boost gauge to confirm that things are happening when you want. If I read the lit correctly, the newer units allow you to program in these parameters directly, so it should be easier to use.

Do not, under any circumstances, rely on one of these things without having some way of monitoring the results. A decent A/F meter is indespensable for tuning. Without one you are flying blind. AICs do not offer the finely tuned options of an aftermarket engine management system, so even an inexpensive A/F meter can get you in the ball park. After months of messing with mine, trying to tune it with an EGT gauge, I installed an A/F meter. In 10 minutes, I had the system working properly. Once set up, you can basically leave it alone.

One other warning: These units do not have access to data on coolant or ambient temperatures, so if you live in a place with wide temperature variations, you may want to tweek the boost gain up or down a notch when the seasons change . In other words, locate the control unit where you can get to it.

Within the above restrictions, I am very happy with my HKS unit. Once set up, it has functioned reliably and consistently. Also, it has an interesting "test" function which fires the added injectors full blast to verify that they are working. This extra shot of fuel can be used to load up the exhaust with the kind of stuff which makes for spectacular flames out the back. My exhaust system is old, but when I replace it, I will certainly experiment a bit with the "test" button to see if I can't figure how to create a subtile warning to those who follow too closely.


Date: Fri, 17 Mar 2000 17:13:47 +0000
From: "David Lane" (dlane@gigue.peabody.jhu.edu)

> I will (of course) need to upgrade my fuel.  I am thinking about the 
> HKS AIC with 2 injectors in the Greddy Elbow.  I will be running 15-20 
> psi of boost on the stock turbos. I'm also upgrading the fuel pump and
> adding an aftermarket fuel pressure regulator. This will all be
> dyno tuned.   Ive heard that the AIC is kinda hard to tune, any
> opinions out there???

The HKS AIC is actually easy to tune. The problem is that the unit itself gives you no frame of reference for your air/fuel ratio--which is what you need if you are going to tune it properly. You say you are going to run 15-20 psi on stock turbos. Even the lower side of that will put you into very dangerous territory unless you have a wide-range A/F rig hooked up for the tuning. Frankly, I agree with Max that 20 psi is beyond the design parameters of the stock turbo system. What I have to say would be best applied for, say 14-15 psi. I defer to 3rd gen owners for better figures.

The system you propose (boost dependent FPR + AIC) is the one I use on my turbo GSL-SE. There are some limitations to this kind of rig.

  1. Neither device "knows" about the other, and your ECU hasn't a clue that it is getting "help," so you have to figure out the best way to integrate them yourself.

  2. The AIC has no feed for engine temperature or ambient temperature--just boost and RPM. Thus, if you tune it on a hot day, it may be a bit off when the temperature drops. This would not be much of a problem in Southern California or Florida, but it is a concern in locations where there is wide variation in temps over the year.

  3. The boost dependent FPR works through the stock injectors, and is thus affected by all the parameters measured by the stock ECU (as translated into the injector duty cycle). The boost dependent FPR also works through the additional injectors, but the AIC only "sees" boost and RPM. You can see how this can become confusing when you are trying to make fine adjustments.

  4. Since the ECU, the boost dependent FPR, and the Additional Injector Controller do not "talk" to each other, and do not operate with the same input, you cannot control your fuel mix as consistently as you can with other fuel enrichment options (aftermarket chip, piggyback controller, Motec, Haltech, etc.). This is not much of a problem with a car like mine, running relatively low boost with a lot of headroom, but I am skeptical about the wisdom of using it for the kind of boost you specified. Your engine would have little tolerance for small variations in A/F mix. Besides, at those kinds of boost levels you would probably need some kind of ignition timing control to keep the engine happy. You get the benefit of integration and timing control in the more comprehensive aftermarket systems--even a relatively inexpensive chip upgrade.

  5. Since the system you propose is relatively imprecise, and can change performance (literally) as the weather changes, you will need some way to monitor it at all times. I am a big proponent of inexpensive A/F meters for cars like mine, but such a meter does not have the resolution to tune the car properly for the kind of boost you want to run. Still, I recommend one as a gross indication of the health of your system. At the same time, a J&S knock sensor is mandatory to keep you safe when small changes bring you too near the edge of detonation. You said your car would be dyno tuned, but that tuning may not be accurate over a period of months and under changing conditions. Boost dependent FPRs are not particularly noted for being consistent over the years. As a final caution, I understand that dyno tuning by itself is not a guarantee of good results. I don't have the details, but one of the true gurus out there told me it was tricky--that what looks good on a dyno is not always the best setting for real life.

AICs are not cheap, and you could probably get a suitable chip for your ECU that would give you better results with more control for the same money. If you really MUST get to 20 psi, I should think you would need an entire aftermarket engine management system, and you would have to ditch the stock turbos. Max Cooper covered that topic much better than I ever could.

On the other hand, if you are looking for a relatively low-tech approach for fuel supplementation with an aftermarket turbo, or for safety if you are going to push stock boost pressures by a couple of pounds, a boost dependent FPR coupled with an AIC is a reasonable approach. Just don't forget to add a J&S knock sensor to your budget. Sooner or later you WILL experience a lean running condition--either as you initially try to tune the system or later in its life when something goes on the fritz, clogs up, or comes loose. Maybe you will just get a little frisky with boost pressures to see if you can't just get a little more power out of it.

Better to see the lights on the J&S flicker than to hear the popcorn sound and see the smoke.


Fuel Cut Defenser:

Mon, 10 Nov 97 18:33:36 -0500
From: "Kyle Krutilek"

I may be off with the following reply, however, this is how its been explained to me, here goes.

The FCD lies to your computer regarding boost levels. It prevents the ECU from cutting fuel in the event of excessive boost at high rpm. This has been referred to as sounding like a "dog barking", however, they are referring not to the car but to the sound that the rx7 owner makes when he/she thinks that the engine just took a dump!

To paraphrase ... if your not running enough boost to hit the fuel cut, you don't need the FCD.

The FCON will allow you to add the additional but necessary fuel when running much higher than stock boost. This is necessary because the FCD will be lying to your ECU which will of course have no idea that its owner is feeding the engine such high boost and therefore the ECU will probably only feed the engine enough fuel to run its normal fuel delivery for an estimated 8 psi or so boost. Probably not enough fuel for the gutsy owners that push it into the teens. May want to invest in an EGT to meter fuel dosage with the FCON, some use air/fuel meters or O2 sensor, matter of preference or faith. There are higher forms of intelligent metering and thought for that matter available to tune the engine.

I have heard of rx7s running open intake/exhaust with a FCD/FCON with performance described as "runs like a motorcycle". Stock engine in this case was short lived.


Date: Mon, 10 Nov 1997 22:35:11 -0500
From: Rob Robinette

I just finished installing an HKS FCON and Fuel Cut Defenser. Before I installed them I did some 3rd gear boost tests. I was getting 10 PSI, 8, spike to 15, and then steady 7 to redline. I believe the fuel cut was occurring and the ECU was resorting to the safe 7 PSI level.

After I installed the FCON and FCD I got 10, 8, spike to 15, and then steady 12 PSI.

This is the important thing: The only mods I have right now are RB intake (with stock airbox), K&N filter, 3" straight pipe cat back, and no air pump and yet I really believe I was hitting the high boost fuel cut when the second turbo came on line and spiked. I'm really surprised that the FCON and FCD solved this 7 PSI boost problem. Just wanted to let you know that even relatively mild mods can cause problems in the 3rd gen. I can't wait to get the down pipe on.


Date: Tue, 11 Nov 1997 07:59:38 -0500
From: Brad Franklin

Just a word of caution, you guys should be careful about hitting fuel cut. It is there to prevent a catastrophe, and is not to healthy itself. Think about your turbo forcing so much air into your engine, then the computer says "too much boost" and cuts fuel. It does the trick, but for a short duration, your engine runs very lean, which can cause severe detonation for a short period. And we all know what detonation can do to apex seals. Be careful!


Date: Thu, 18 Mar 1999 10:03:01 -0500
From: Tom Walsh

I know someone has already replied to you telling you not to use the FCD without a computer, but let me explain why you should not use the fuel cut defenser.

The stock ECU has a programmed fuel cut that varies depending on RPM. During the switch over (4000-5000 RPMs) is as high as 13lbs, but comes back down to 10lbs as you approach the redline.

The Fuel Cut Defenser plugs into the MAP (Manifold Absolute Pressure?) sensor, located on the firewall in the area of the throttle body. The FCD then supplies the ECU with a modified reading of the MAP sensor. This modified reading is basically a lie to the ECU to prevent it from hitting the fuel cut (normally 10lbs of boost).

Now lets think about this. The MAP sensor's job is to supply the ECU with a current pressure reading so the ECU can add the correct amount of fuel to the mixture and prevent a lean condition. Now, if you are going to run the car at 14lbs of boost (which I do not recommend, but that is a personal recommendation), and the FCD is telling the ECU you are only running 10lbs (to avoid fuel cut) there is a difference of 4lbs of boost that the ECU has not added fuel for, thus you are at a very lean condition and this can lead to detonation.

So in short, if you are planning on running your car above stock fuel cut, get a computer that will allow you to do so (Pettit, PFS, Wolf 3D, G-force, etc...) by removing the fuel cut from the ECUs program.

Who would use the fuel cut defencer then? The only people, I feel, that have a need for this type of device (FCD) would be those of you that live in a cold environment, but have the car stock. Often times, with the cold air, your car will run a higher amount of boost and you might occasionally hit fuel cut.

So why fuel cut instead of ignition cut? "Fuel cut" cuts out the fuel being injected into the motor during the intake cycle of the motor. This causes a momentary lean condition inside the motor. Is that bad? Yes. So why did they use an ignition cut instead. This (fuel cut) is actually a standard practice across the industry. It was determined, some time ago, that ignition cut was not the best solution to the problem due to the fact that the unburned fuel remains inside the combustion chamber and can "wash" away the lubrication that lines the combustion chamber walls. There is also the possibility that emissions also had a determining factor into this but I am unsure as to how much.

The Simple Skinny: If your car is stock and you hit fuel cut every once in a while, while driving around town, then you should get the FCD because the fuel cut is doing damage, however slight, to the motor.

If you want to raise the boost levels over the stock fuel cut level (perhaps using a Profec B, which I use) get a modified ECU that has had the fuel cut removed.


EVC (Electronic Valve Control):

Controls boost pressure.

Date: Thu, 17 Aug 2000 10:41:12 -0400
From: "David Lane" (dlane@gigue.peabody.jhu.edu)

> Now that carparts.com has HKS products I might buy a boost
> controller. But they have the HKS EVC IV and the original EVC.
> Which should I get for my car?  I've always heard that fuzzy logic
> is not good for third gens. Does anyone know if the original EVC
> has fuzzy logic and if it is dual solenoid?

I recently switched from the EVC I to the EVC III (similar, I think, to the IV--at least I am going to assume so for the purpose of this message).

Unfortunatley, the information below may not be applicable to your case, because I doubt that the "original" EVC (EVC I) is still available. Rather, they are probably selling the current fuzzy logic EVC IV, and a more basic unit--probably designed to compete with the Gready Profec B at a lower price point, and without some of the fancy electronics. The HKS website shows something called the "EVC EZ" in that category. I suspect these are the two units priced at Carparts.com under the titles of "EVC" and "EVC IV." Unfortunately, I wrote the following comparison and contrast between the original EVC I and the EVC III (which I assume to be similar to the EVC IV) before checking out the Carparts.com web site. You might be interested in reading it anyway--just so you will have a better idea of what questions to ask if you call Carparts.com about the less costly unit. Also, it is pretty complete about how to deal with the fuzzy logic unit. Finally, I am too lazy to re-write it.

The EVC I came in two versions--one for integregal wastegate, and one for remote wastegate. The EVC III has a switch on the back. I believe the "single" and "remote" designation is about one or two ports on the side of the wastegate.

The EVC III is much easier to use for a variety of reasons. The fuzzy logic feature can be bypassed. The fuzzy logic itself is pretty neat, but it requires you to do three identical runs in "learn mode." The instructions for doing this with sequential turbo systems require you to begin the runs when the 2nd turbo comes on line. Obviously this is difficult to nail exactly the same way three times, and they say as much in the instructions. In fact, it is at that point they tell you how to bypass the fuzzy logic feature.

For what it's worth, I ran mine for a day with fuzzy logic bypassed--couldn't get the learn feature to "take." The next day, I was successful. My impression is that the fuzzy logic is an improvement.

The EVC I has the same features as the EVC III running without the fuzzy logic. However, there are the following operational differences:

  1. Scramble boost control is an add-on box with the EVC-I. It is integrated into the EVC III.

  2. Adjustments for Low and High boost on the EVC I are trim pots in the back of the unit. Adjusting this is awkward in that you have to dismount the unit and turn the screws--which is hard to do by yourself under boost. Thus, you have to turn a little, test, and repeat until you get the results you want. In contrast, the EVC III has a digital interface, so you just dial up your target boost levels directly, and make a small modification or two if you don't get the anticipated results on your boost gauge.

  3. The EVC III has an overboost protection mode that you set where you what it. If the overboost threshold is exceeded, boost drops to wastegate level. The EVC I does not have that feature.

  4. Both EVCs have a manual control so you can mess around with boost without tampering with your Low or High presets. The EVC I is a knob on the face of the unit. You watch your boost gauge and turn the knob until you get what you want. The EVC III, is set by punching up the boost you want on the digital display (same as with any other setting).

  5. The EVC III has an "offset" feature to calibrate the unit up or down a little to compensate for installation variations.


Date: Fri, 03 Apr 1998 01:29:19 -0800
From: Andrew Chiao

The electronic boost controllers such as the HKS EVC IV and the other ones out there "trick" the wastegate to stay close when it would normally open. With the use of a stepping motor attached to the elec. boost controller, a lower pressure reading is sent to the wastegate than there actually is. For example if your wastegate is suppose to open at 10psi, but you want to turn up the boost to 12 for instance, then how are to supposed to reach 12 when it closes at 10? This is done, for example, by telling the wastegate it's at only 8psi when it's actually at 10, and telling it its at 10 when it's actually 12. Therefore you could reach your desired 12psi. This is my understanding of how it works, but I'm pretty sure that it's right.


Date: Fri, 03 Apr 98 08:21:50 -0500
From: "Linthicum, Sandy"

The controller bleeds off air from the line controlling the wastegate so the flow/pressure in the line that would normally have the wastegate fully open at 10psi (ie.pressure on diaphram overcomes the spring pressure holding the wastegate closed) does not occur till an actual 12psi. Only a limited amount of air can be bleed off by the soloniod, which is the reason for a restrictor in the line which limits the amount of air that can pass.

The computer provides fuel based on TPS, MAP, and other sensors. As boost rises, it will provide more fuel up to about 12psi which is where the stock ECU does a fuel cut (total) to protect the engine. This is one of many reasons you need a fuel computer if you are going to run boost over 12psi.


Date: Fri, 3 Apr 1998 11:34:55 +0000
From: "David Lane"

I can't speak for 3rd gens, but the HKS EVC on my car does not work the way a previous poster implied. What follows is for a typical wastegate on a single turbo system.

First of all, the wastegate OPENS to create a path around the turbo for the exhaust gasses to flow. Most wastegates have a valve that is controlled by a diaphragm. Boost pressure is brought to one side of the diaphragm, tending to open the wastegate. A spring acts on the other side to keep the wastegate closed. As long as the spring on one side of the diaphragm is stronger than the boost pressure on the other side, the wastegate will remain closed. However, there will come a time when the boost pressure overpowers the spring and allows the wastegate to open.

Now, the problem is that the wastegate tends not to "pop" open all at once. If you are set for 10 psi, the typical wastegate will start to open a little before that, in effect cracking the valve open before necessary which makes the engine take a small amount of extra time to arrive at max boost. The theory is that you can increase power if somehow you can positively hold the wastegate closed until exactly 10 psi.

The aftermarket electronic boost controllers feed boost pressure to the back side of the diaphragm (the same side as the spring) to assist in holding the valve closed untill exactly the right moment. This results in slightly enhanced performance. However, the reason many people turn to these devices is not so much for additional power as for better control of boost levels. However, it must also be said that if you have better control of your boost levels, you can set it a bit higher without worrying about it changing by itself. In that sense, the car does end up putting out more power in daily driving.

The spring and the air pressure used to control most wastgates vary in value depending on ambient temperature, humidity, etc. In some cases (depending on your local climate), your boost pressure will be plus or minus a psi between the morning and the afternoon. This is not a problem for a stock turbomotor with huge amounts of head room built into the system, but for those of us who want to run nearer the edge, it is critical.

Secondly, since the EVCs are electronically controlled, you can change the boost setting remotely from the head unit within easy reach. The HKS, for instance, offers pushbutton access to a low setting, a high setting, and a variable setting--all of which you can set to your taste. I believe the Greddy unit is similar.

Finally, the more recent units offer a "temporary" setting which allows you to trigger additional boost of a pre-set amount for X time--after which the standard boost setting is re-established. This allows you to run full throttle at a conservative boost setting for daily driving, but to have instant access to your maximum setting if you need it in anger. A secondary benefit of this feature is to avoid wheel spin in your lower gears, while increasing boost for the upper gears.

While this post is accurate for single turbo, single wastegate sytems, I don't have the background to apply it directly to the more complex sequential turbo set-ups on 3rd gens. Earlier posts indicate that electronic boost controllers are in use by some list members, so I can't be too far off.

Knight Sports

Date: Sun, 15 Mar 1998 21:52:49 +0000
From: "Steven M. Robertson"

If I were to recommend any one thing of Knight Sports, it would have to be the boost controller EBS III. It is made specifically for our cars and also controls the sequential turbo switch. It is supposedly quite easy to install, about the same as a boost guage and turbo timer with a good harness together. Those of you who have gone non-sequential can possibly get a version without the SCA (sequential control adapter). Remember never to set ANY boost controller over 0.75 kg/cm2 (~10.8) without a fuel cut defender and never above 0.80 without extra fuel management. Being a conservative company, Knight Sports never recommends setting boost above 0.90K (~13.0) even with their chip, though the chip has fuel maps for up to 1.0K (~14.5 depending on who you talk to).


Date: Wed, 24 Dec 1997 23:49:48 -1000 (HST)
From: F8LDZZ

(It) bumps up the fuel maps a bit but not any significant change. SFC stands for "Simple Fuel Computer". What were you expecting? All it does is intercept the signal coming from the MAF sensor and modifies that signal going back into the ECU. From there, injector pulsewidths can be changed.

Yup, APEX'i only makes the SFC in a single, universal version. This unit will work on almost all turbocharged vehicles coming out of Japan. You can change the configuration by the single knob and DIP switch bank in the rear of the unit.

APEX'i also makes a BFC (I think) that's just a plug in unit with a single rotary knob to adjust rich/lean over the entire RPM band. These are vehicle model specific, and I don't think there is one that applied to any of the RX-7's. This is basically what the HKS PFC F-CON does.

For $400, the only thing that comes close is a Field Hyper-SFC unit. A brand new HKS PFC F-CON costs closer to a US$1,000! Add a GCC II for another US$400, and you got one helluva electronics package with almost no money in your wallet. The APEX'i SFC does what the F-CON and GCC II do combined at a whomping 1/3rd of the price!

APEX'i was started by a bunch of HKS tech engineers that were tired with the high cost of the HKS stuff. If you noticed, a lot of the APEX'i components can be easily compared to a lot of the HKS stuff, especially with electronic units. These guys are as good, if not better due to lower MSRPs, than HKS. Although most US consumers only see the APEX'i Skyline GT-R in ads, they have far more knowledge than with the R32's and R33's...

Personally, I never really liked *ANY* of the US reps for these Japan companies. This includes HKS and Trust/GReddy. I think all of them have no idea what the hell they are selling and info about their own products.

> I would avoid any boost or fuel products from them. The boost
> controller really has a large spike when the turbo switches.

This is too much of a blanket statement. I've seen lots of problems with boost spikes with almost any boost controller system out there for the FD, including the PFS Purple/Gold boxes; do you mean these are a waste of time? I've seen an AVC-R installed in a black FD locally that had rock solid boost levels when under WOT. The good thing about the AVC-R is that it has its own atmospheric sensor, so basically it does what an HKS III ATM does. With the ATM sensor, the EBC has a much more accurate control of the boost levels. I don't know what your experiences with the AVC-R is, but it could be something else that was causing the boost spike. Another side note, the AVC-R has an injection pulsewidth monitor built into it. This might or might not be of use to you.

What makes it more attractive is that you can change almost any part of your fuel system, and you can always go back and retune the SFC, unlike other systems. Changing fuel injectors? Changing fuel pump? Adding a boost inline pump? Adding a boost dependent fuel pressure regulator? No problem, just retune the SFC...

The SFC runs 5 rev levels from 800RPM to 7200RPM in 5 discrete increments. You can dial in +-30% on the fuel injection pulsewidths at each level. Be VERY CAREFUL about dialing in too much at the top end as you might be saturating your fuel injectors.

Installation is very easy, as there are only 5 leads. +12VDC constant, +12VDC ignition, ground, input MAF, output MAF. That's it.

We can dial in the SFC to run real rich (solid 1 red bar on a Cyberdyne AFR gauge) at over 0.9VDC on the O2 sensor if you want. This doesn't really mean much though.

Some of the downsides are that the unit might be (not confirmed) modifying pulsewidths full-time. This means under part throttle conditions, this might not be a good thing. Also, like I stated before, it's very possible to dial over 100% on the top end, since the SFC is designed to go +30% on all RPM levels; you do *NOT* want to saturate your fuel injectors! You might want to keep the unit in a semi-secure are, since it's very easy to change the settings from what you've safely set them for. A friend took his FC to the Mazda dealership, and the idiots there set all his SFC settings to -30%!?!?! Lucky thing he didn't hammer the throttle when he got the car, but the car did bog on him trying to drive out of the dealership lot!


Date: Thu, 25 Dec 1997 03:03:55 -0800
From: "Hung-Jen Hung"

I just double checked the CAR BOY Jan 1995 issue. AFC works only for RX7 FC3S 13BT. You need an AFC II for FD3S 13B-REW.


Date: Wed, 21 Apr 1999 18:01:15 -1000 (HST)
From: F8LDZZ

A'PEXi Super AVC-R

Advantages:  *closed-loop operation - dedicated boost sensor
             *"self learning" 
             *two boost levels
             *fuel injector pulsewidth monitor + warning
             *1/4-DIN size
             *smallest electronic valve in the industry - easier
              to install versus HKS EVC or GReddy PRofec untis
             *Probably the best EBC out there for the money - street 
              priced under $450 if you look around
Disadvantages:  *pulsewidth LED's not too sharp - kinda floods the entire
                *takes a few seconds to toggle between the two boost
                *not always easy to set the self-learning right
                *boost/vacuum in bar/mmHg

Jim, I think you might want to wait for the new A'PEXi Super AVC-R. It just came out in Japan, and it blows away anything that's out in the US now. The face glows Indiglo blue...it might match your car. :)


From: Azeem (araja@kestelsolutions.com)
Date: February 23, 2000

I've been using the new AVC-R in my FD for a few weeks. Here is what I think about it, plus some notes on its operation.

Summary: The unit works fairly well in my FD. It keeps boost stable, controls the transition spike, controls initial boost spiking, is temperature stable, and is extremely flexible/programmable.




Finally, for more info on the unit:

Detailed install & tuning info coming soon...


Date: Mon, 10 Jan 2000 11:41:43 -0800
From: "Les D" (les_d@my-deja.com)
Subject: A'PEXi Super AFC

What it does is fool the factory ECU by altering the boost signal ( MAP ). So if you want to richen the mixture at 4000 rpm, you can change the 'graphic equalizer ' sliders to add a few percent of fuel.

Keep in mind that when the factory ECU is in closed loop operation, it will look at the 02 sensor and pretty much ignore what you did with the Apexi unit. So when playing with settings under steady driving conditions, you won't see a difference on the O2 AF meter, if you have one. BTW, you should have one when tinkering with fuel.

On my FD, I plan on raising the fuel pressure and then dialing down the MAP signal with the Apexi. This allows higher boost overall with no leaning out due to a flat cutoff that the lame 'fuel cut defenser' gives you. This should be good for 300HP at the engine.

Problem: doing this also makes the ECU inject less oil, because it thinks the engine is not as loaded.

Solution: Offset the feedback resistor on the meter pump to regain the WOT oil flow level.

(Ed.'s note: Or you could also go the pre-mix route and add oil to your gas tank. --Steve)


From: Dave Disney
Date: Jan 14, 2000

Shane Racing is advertising some sort of APEXi Power FC that completely replaces the stock ECU and is programmable via a keypad.

From the web site:

We are now using the Power FC in our project RX-7 car. It is due to be released soon. This is a brand new, state of the art fully programable stand-alone fuel, ignition and boost computer. It completely replaces your ECU in your 1993-1995 RX-7.

They are sold fully dyno tested and tuned per your performance level. The Power FC is one of the most technologically advanced fuel management systems for today's car. The Power FC allows access to every parameter of tuning within the ECU. Installation of the unit is the easiest on the market. Simply switching out the factory ECU and plugging in the Power FC transforms the factory ECU into a fine tuning instrument capable of growing with the tuning menu. Tuning parameters include: ignition timing map, injector pulse, timing adjustment, boost control, acceleration enrichment compensation, fuel/ ignition test, ignition cranking fuel adjustment, injector duty cycle,water temperature correction, rev-limiter control. All parameters of the vehicle including water temp, oil temp, oil pressure can be monitored from the display. The optional Power FC Commander allows complete tuning of the vehicle with an easy to use keypad.


Date: Mon, 31 Jan 2000 15:40:11 -0500
From: "Ryan Schlagheck" (ryan.schlagheck@worldnet.att.net)

For starters, the Power FC is a direct replacement for the stock ECU, so you can toss the stocker, keep the harness, and have a computer with as much configuration latitude as the likes of the Wolf 3D and Haltech (give or take a few). The Power FC is literally tapped into all of the necessary points on the ECU and allows the user to modify settings at will. As such, you have control over when the cooling fans come on, control for timing on leading and trailing individually, and even the switchover point for the primary and secondary injectors. What that tells me is I can run much larger primaries and secondaries and tune the fuel delivery to let me run 14psi at 60% if the injectors are sized right. It's that kind of flexibility that will open up the possibilities for more FD owners bitten by the hp bug. I know Carlos tried with great success to mathematically adjust fuel delivery with larger injectors with an EFI, but then he went to the Wolf 3D, which tells me something about upsizing injectors with the EFI. I'm not so well-versed on all of the Power FC capabilities, as I've had a dialogue (now long over) with a Japanese FD owner who patiently sat with the manual and paraphrased/translated for me via email and chat.

Suffice it to say, I'm chomping at the bit for Apex'i and Shane Racing to release it for the US market. I'm still wondering whether Sigfried got a Japanese-spec Power FC, since those were tuned for 100 octane fuel, and that's why he's running lean on the O2. I'm told that the 100 octane and Japanese language issues are the only holdups. Don't know if that's all though.


You would probably need to keep the stock computer tfor such functions as air conditioning, etc. --Steve


Date: Tue, 28 Mar 2000 22:34:30 EST
From: Dunder@aol.com

To set the record straight on the FC:

  1. It is strictly stand-alone (wouldn't an 8bit and a 16bit computer have trouble communicating?)

  2. All modifications are direct data entry, not % changes as in the PMC (no way to modify data to the stock ECU)

  3. Although Apex will sell many products (exhaust systems, for instance) to anyone with a business license, an FC dealer has to attend factory schooling on the unit and has to have a program in place to develope the maps. Apex - USA will not allow the units to be sold untuned. Units sold as such are bootlegs (hence non-English instructions)


Date: Wed, 29 Mar 2000 09:12:17 -0500
From: "Wade Lanham" (walanham@mountaineergas.com)

The FC sounds cool, and if I were in the market for an ECU right now, I might consider it. However, it seems like a lot of people are over-excited about this ECU, and some are even considering getting rid of a better system (IMO) to buy an FC. This I don't understand.

  1. There will probably always be more people using the PMS/Haltech here in the states, and thus more help/knowledge.

  2. The FC hasn't been proven yet as a reliable system. Bugs may pop up 6 months from now.

  3. There is no datalogging feature currently available AFAIK. I couldn't tune my car without datalogging. YMMV.

  4. What are the benefits of the FC over EFI, Haltech, and other popular (and trusted) systems? The ability to control oil metering?

I just don't understand what all the excitement is about, because everything that I have read about the FC here on the list makes it sound like it is not an improvement over the existing systems in the same price ballpark. Also, there are other systems that work great, and we're assuming the FC works great too. Given three properly tuned cars, one with a Haltech, one an FC, and one an EFI, what's going to be the difference? You're not going to be able to tell the difference in drivability or power.

From what I've heard about the FC, and what I know about the PMS, I'd still recommend the PMS to someone in the market for an ECU, since the exclusive features of the PMS seem more significant than those of the FC. I guess I need some more convincing. ;)


Date: Wed, 29 Mar 2000 05:00:25 -1000
From: "Wendell Yamada" (hyperrex@hawaii.rr.com)

Well, I guess I'll jump in and add what I know about the Power FC.

  1. So far as I know, you can buy the Power FC in the US along with the Power FC Commander keypad, but the laptop software is unavailable to consumers (so far). I have no idea what features this adds to the Power FC, but I'm willing to bet it adds datalogging.

  2. Power FC's come preprogrammed for 100 octane, unless reprogrammed by a reseller. (Ray)

  3. You can't just plug in Japanese Power FC's. You need to switch a few pins around.

  4. The thing ships with a manual entirely in Japanese. There is no English manual available. I'm translating one now, but I don't exactly trust my translation so no, I won't go about distributing it. No way I want to be liable.

  5. XS Engineering sells the Power FC preprogrammed with their single turbo kits, but does not formally support Power FC's in any other application. You couldn't call them and Q&A specific tuning questions. They're sold as "you figure them out" kind of deals.

  6. $300 is entirely not unreasonable for tuning. Many stand alone systems don't supply you with base maps, but they'll sell you one for oh, about $300. If Ray is going to offer tech support as well, that's probably worth more than $300. Please don't raise the prices, Ray. lol.

  7. The Power FC uses the stock wiring harness. Depending on the condition of your wiring, this is either a good or bad thing. I've seen a lot of wasted harnesses on modified FD's. I consider getting a new wiring harness with, say, a Haltech E6K a real bargain.


Date: Sun, 02 Apr 2000 19:09:10 -0500
From: brad barber (bradrx7@swbell.net)

Here is my first Apex PowerFC report.

Due to severe thunderstorms in the area, I just was able to squeak in a couple of hard runs a few minutes ago. I will run the car at Texas World Speedway this coming weekend and I'll give a full report on the 90 mile highway trip along with two days of hard track use

Install was very easy. Where the stock ECU uses screw-on brackets, the nicely built Apex unit velcros to the stock ECU bottom bracket. The Power Commander's DIN connector requires elimination of the top bracket, but this is no problem.

The car cranked right up and idles very smoothly. Watching the sensors' voltages on the display was very interesting. Every sensor on the engine is available and matching the voltages to my gauges was unique. I took some notes and started a tuning book for comparison purposes. After warmup, I took the car out on the wet Houston streets for a little stop and go driving. The first impression was total smoothness through the 3K rpm range. Since 1993, I have lived with a mild stumble at 3K. Now it has vanished. The car idled fine and street tractability was perfect.

I got on the freeway and was able to make a hard second and third gear pull before going too fast for the weather and road conditions. The engine felt very strong and smooth. The Profec handled boost perfectly with the PowerFC with 11 primary & 12 secondary like I run it.

Later in the day we had a break in the weather, so I went out in search of a freeway outside of Houston. I was able to get two full third gear pulls in before running into Valentine One fireworks. (It is damn hard to do a tuning run in a big city.) The car felt strong, but it always feels strong. The smoothness was what interested me most. I don't know if the smooth power delivery is a function of a 16 bit vs. 8 bit ECU, Ray's tuning, or a combination of both, but it is gratifying.

The PowerFC looks to be a great upgrade. Ray Lochhead hit the tuning dead on for the motor he built me, which I find amazing.


Date: Tue, 11 Apr 2000 00:38:41 -0500
From: brad barber (bradrx7@swbell.net)

I ran the car at Texas World Speedway's 2.9 mile road course this weekend. It was a very good test of the Apex PowerFC ECU replacement.

The power is now very tractable, precise and smooth. Huge throttle inputs can be applied evenly and I have NEVER been able to use throttle modulation like this before with this car. As my racer friend, Jason Hart said after driving the car, "Your car used to be a bad-ass weapon that you needed to be on top of all the time, but now it is lean and ready to fight. It pulls like it's naturally aspirated and not a turbo anymore. Really awesome." You track guys will understand that quote, I'm sure.

Boost levels were easy to modulate. We experienced very cool temps on Saturday and I used the Profec B to make a small change to compensate. As temps rose, it was easily brought back to the level I wanted. Boost was rock solid and transition, as I mentioned last week, has vanished.

I suggest anyone who is looking for an ECU to seriously consider this unit. It isn't cheap, it lacks data logging, but it works like a dream. The Commander has a learning curve, but after a talk with Ray Lochhead I was able to make a few idle map and boost solenoid changes easily. I wouldn't feel very good diving into the changes without help, so I would suggest getting yours from one of the authorized vendors. We beat that to death last week and I'm not wanting to debate the issue again. It is my .02.

Bottom line, I am very glad I have the unit.


Date: Sat, 18 Mar 2000 09:52:54 -0800
From: "SR Motorsports" (ray@ecis.com)

The Power FC has been in our car since November of 1999. We have four cars with them now.

The unit does control boost. Primary turbo hit and also secondary. The optional boost controller does a better job though not as good as the AVC-R unit , as in our car shows.

It has removed the 3k stumble in our cars.

You are correct that with the ability to modify fuel maps / trailing and leading timing at 400 possible points ( 20 by 20 table each one ) for a person who isn't comfortable tuning an engine could be an unforgiving experience. This is why we only offer a _tuned_ Power FC unit for each FD RX-7. They are able to be updated at any upgrade .


Date: Sat, 18 Mar 2000 18:17:54 -0800
From: "SR Motorsports" (ray@ecis.com)

The Power FC which we use in our car is a _plug in_ unit. It is installed in place of your stock ECU unit. It doesn't even require you to open your hood for the installation !

The Power FC runs the oil metering pump .This is something that the other stand alone systems cannot do , requiring you to pre mix oil in the gas tank. We have not found anything that this unit won't do.

We are currently making 850cc injectors maps to allow for drop-in (4) 850 cc injectors to allow for 15 psi safe boost levels. We also have a fuel system for the Power FC which will support 500 HP worth of single turbo power . This should be good for most people :)


Date: Tue, 11 Apr 2000 19:13:10 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

I have written the following to clear up any confusion.

The Power FC is currently released for market testing. It has been released for the FD because FD owners, like yourselves, generally have a more mature and serious approach to tuning vehicles for performance compared to Honda owners. Although I have completed the development of the Honda Power FC, you will notice that only the FD unit has been released for the stated reason. I am constantly in contact with our Power FC retailers to see and hear what is going on with the Power FC.

Contrary to what I have been reading on the RX7 list, the development of the American market FD Power FC has been completed. I have read something about Apex having SR and XS develop programs for us. This is absolutely untrue. Apex is an Engineering based company (out of 230 employees, over 130 are Engineers and technicians). With all of our Engineering power, we do not have the need for our customers to develop Power FCs for us. That is our own responsibility. I have already put the FD Power FC through 4 seasons of testing for over one year with intense amounts of development. The Power FC unit itself it designed and developed entirely in house. It uses a proprietary 16 bit processor designed specifically for Apex. It is entirely capable of running sequential turbo systems, boost control, etc. It is designed as a ECU replacement, not a piggyback or intercept type system. It is capable of perfect driveability (driveability being limited by engine porting and injector atomization of large injectors) and massive horsepower levels. In fact, one of my fellow Engineers at Apex Japan just completed the tuning of a 711 horsepower peripheral ported two rotor FD with an off the shelf Power FC.

Currently in America, Apex operates on a staff of 10 people with one Engineer and two technicians. With the constant need to develop new products, we are unable to fully support the Power FC customers at this time. This is why we only chose three retailers to sell this product: SR Motorsports, XS Engineering, and SPI. We offer them the profit, but they also take care of the customers. I'm sure many of you know that in America, many shops and so called "tuners" barely know more about tuning than yourselves. In choosing these three retailers, we made sure that they had the equipment, resources, and ability to supply customers with reliably tuned Power FCs.

Before you ask, "Why is the Power FC only available through limited sources?", please remember that this product was originally intended for the professional tuner in Japan. In Japan, you will find a tuning shop on every other corner of major cities that are more than capable of tuning the Power FC and many other fuel systems. There are so many tuning shops because the Japanese tuning aftermarket is 60 billion dollars strong. In America, the aftermarket is merely 6.85 billion (this includes trucks, motorhomes, and van conversions). Likewise, in America, the Power FC is intended for professional tuners with professional Lambda (A/F) meters, datalogging, and dynamometers. This is not to say that the Power FC cannot be tuned by an amateur, but that the best results will come from a professional tuner. I understand that there are barely a handful (one handful) of professional tuners in America and this is why we were very careful in chosing the premier tuners to sell the Power FC.

Some factors we took into account when choosing the Power FC retailers were the tuning abilities, price protection in the past, and available resources. One of our Power FC retailers, Ray Lochhead of SR Motorsports, has more than proven his abilities with the Rotary engines with his 8.98 second FD3S and 9.3 second SA22C race car. His engine building is very good and his knowledge of fuel systems is second to none. His conservative approach to street cars, ability to build race cars, and tuning ability make him a prime candidate for a Power FC retailer. The fact that he is sponsored by Apex really has nothing to do with selling Power FCs. Ed Bergenholtz (9.68 second CRX) is sponsored by Apex, but Bergenholtz Racing is unable to sell the Honda Power FC. Another Power FC retailer, XS Engineering, has developed numerous 9 and 10 second Hondas, many very fast 400+ horsepower street FDs, 700+ horsepower Supras, and has a high degree of technical knowledge. The head tuner at XS, Koji Arai, is from Japan and has had extensive experience with tuning Japanese sports cars. Also, XS has been tuning Nissan SR20 Power FCs for the last year and a half. The last retailer, SPI is our east coast distribution office. Hubie Fuh is the president of SPI and despite his keen business sense, he is also very mechanically inclined. He has built many 600 plus horsepower street driven Supras and has experience with Hondas as well. However, SPI has not actually sold any Power FCs to date. This is because SPI is our east coast distribution center and is not actually a retailer. I will be going to New York at the end of April to discuss details of how SPI will sell the Power FC.

Despite the fact that I was the head tuner at XS almost three years ago, I am not the owner. The president of Apex Japan recruited me for the start up operations of Apex Integration, Inc and gave me an offer I couldn't refuse. I just want to clarify that it is not "politics" that allows SR, XS, and SPI to sell the Power FC, but rather qualifications.

Ideally, the Power FC should be purchased by one of these three retailers. At this time, there is no technical service available directly from Apex Integration. As stated before, due to our limited resources, it is much more efficient for us to intensively train those 3 tuners, than to have a mediocre support program for this powerful product. If you should call Apex, we will ask for your serial number off the unit to insure that your unit was purchased here in America. Then we will direct you to one of the three retailers if your unit was in fact purchased from America. This is the extent of the service you will receive from Apex Integration. This is why we strongly suggest you purchase your Power FCs from one of the three authorized retailers. All three are very strong in tuning and therefore I cannot recommend which particular one you should purchase from. However, if the Power FC is tuned by either one of these three retailers, you will be satisfied with the results.

On a personal note, I first saw the capabilities of the Power FC during my engineering training at APEX headquarters in Japan almost 3 years ago. As a fellow enthusiast, I knew that withholding this computer system from the US market due to language barriers, politics, and cost barriers was unfair to the US enthusiast. Prior to my employment here at APEX, I was one of those people deprived for years by other manufacturers of their top products. I have done everything in my power to bring you this computer as soon as I could. With my given resources and time constraints with other projects, this was the most ideal situation I could find.

I also have plans on launching the US POWER EXCEL program later this year in which I hope to add more POWER EXCEL shops. I will be traveling all over the US to pre-selected tuning shops to train them to sell the POWER FC. These POWER EXCEL shops will resemble what XS, SPI and SR Motorsports are doing now. I hope that my efforts will enable people outside of California and New York to purchase the POWER FC and have their vehicles professionally tuned.


Eric Hsu
Chief Engineer
Apex Integration, Inc.


Date: Thu, 13 Apr 2000 14:42:14 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

To answer some questions:

Q: Automatic FDs

A: Unfortunately, the Power FC will not run Automatic FDs because the factory ECU also controls the transmission. However, if you were to eliminate the need for the tranmission computer by using a manual valve body or stuffing a Chevy TH350 in the car, then technically the Power FC can be used for fuel and ignition control. There are no plans to create an automatic FD Power FC.

Q: Power FC for FC3S

A: In Japan, we have a unit for the after minor change FCs (89-91). However, there are some differences between the US and Japanese market cars and the unit will not plug in and fire right up. I may develop the FC unit sometime in 2001, but there are no plans this year.

Q: Power Excel Shops

A: The basic qualifications of a Power Excel shop would be:

  1. experienced tuner
  2. dynamometer (engine or chasssis)
  3. Horiba A/F meter
  4. completion of Apex training course

Please keep in mind that Power Excel shops do not currently exist. The FD Power FC is released as a market tester and the existing three retailers have been chosen because I have worked closely with them before.

Q: Other shops selling the Power FC

A: Currently, the Power FC is sold as a market tester. The Power FC WILL NOT be available through other retailers at the moment because I do not have an existing working relationship with them. I understand that there are other qualified shops out there, but this is the best that Apex can do right now. Please be patient and the Power FC will hopefully be available at your local tuning shop. Otherwise, it can be purchased by the three retailers who are all developing their very own programs for different engine/turbo/injector combinations.

Q: 3k stumble

A: There is no longer a 3k stumble when using the Power FC. In fact, owners of the Power FC will tell you that driveability is BETTER than stock. The electronics and design of the Power FC is much better than the factory Denso unit.


Date: Wed, 17 May 2000 17:30:53 CDT
From: "james rojas" (james_rojas@hotmail.com)
Subject: (rx7) rx7[3] Auto Tranny ECU is separate...

I talked to several people that know the auto pretty well and there are in fact two different ECU's. The tranny ECU is separate from the main ECU. The only interface for the tranny housed in the main ECU is the instruction for HOLDING gears and retarding timing between shifts. This is why I have seen cars with automatic trannys that function with the Power FC in there. They can't hold gears because there's no automatic ECU to talk to and this is why the HOLD led is ALWAYS on. Makes sense now.


Date: Thu, 13 Apr 2000 17:39:07 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

According to memory, the 3k stumble occurs the moment that the secondary injectors actuate under vacuum or light boost. The stumble becomes more apparent as the exhaust and intake systems are opened up (i.e. downpipes, mufflers, etc.). It can be ALMOST cured with rom tuning and/or Super AFC tuning.

As for data logging capabilities, the PC software and datalogging equipment will not be available to the public. The future Power Excel shops will have to sign strict contracts and pay a monthly lease fee to use the PC interface and datalogging equipment.


Date: Thu, 13 Apr 2000 19:31:40 -0700
From: "Eric Hsu" (dailo502@hotmail.com) Subject: (rx7) [3] Power FC

Actually, even if you wanted to pay for the data logging capability, you couldn't. It simply will not be available to the public. There are no plans to make our interface technology available to the public either. I'm sorry if this changes your mind about purchasing the Power FC, but there simply is no other ECU as powerful for the money and simplicity (plugs right in and starts right up!).

You are able to monitor what is going on with the FC Commander (optional hand held controller). There is also a monitoring mode that allows you to view the trend of the functions below. Functions that can be monitored are:


Date: Mon, 17 Apr 2000 11:50:06 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

In response to your questions:


Documentation in now available for the FC commander. Please contact your place of purchase for a copy. We have shipped ample amounts of instructions to the current retailers.

Sensor Limitations

It is true that the stock MAP sensor can only read up to 1.25kg/cm2 of boost, but we offer our own MAP sensor that plugs right into the stock MAP sensor. Our sensor can support up to 2.0 kg/cm2 of boost. There is nothing wrong with the Mazda coolant temp sensor; it reads perfectly fine. I believe it may be that other brand piggy back computer that is at fault.

Boost Control

The boost control within the Power FC for the FD is closed loop. Boost can only be increased to 1.2kg/cm2 on the stock MAP sensor. When using a single or twin turbo upgrade (two big turbos), our boost control kit can be added ($380). This kit includes a solenoid (same one used with our AVC-R), MAP sensor (2.0kg/cm2 boost), and harness.


I forget the gentleman's name inquiring from Singapore, but I suggest you purchase the unit from America. I am not familiar with the Singapore tuner market and therefore cannot recommend any shop specifically. I believe Apex has a distributor there, Speedworks. You can contact them for further information if you like, but I'm pretty sure they will know next to nothing about the Power FC. Or you can contact one of the three American retailers.

Map Switching

Map switching is not possible. The Power FC only uses one set of maps. Changes must be made by handheld controller or by a future Power Excel shop.


Once again, I am sorry you guys feel the way you do about the lack of data logging. However, this is NOT going to change. If Apex has lost your business on the Power FC, then I hope some of our other products can meet your needs. Please do not waste any more of your time asking for datalogging, because it will not be available anytime in the near future.


Date: Tue, 18 Apr 2000 10:35:54 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

Answers to your questions:

  1. Datalogging

    I have previously explained why datalogging will not be available: my boss in Japan says so. Not even the President of the United States can get datalogging.

  2. Power Excel Datalogging

    Yes, Power Excel shops will be able to datalog, both for their own use and customer use. However, I am sure that the shops will charge for them to go out to your racing event to do so. You will have to deal with the individual shop. We actually have two forms of datalogging, one within the PC software and another separate unit with analog inputs. Perhaps the separate unit can be "rented" from certain shops. This will be up to the individual shop.

  3. Map Changing

    There are no provisions either in the Power FC or the FC Commander for map switching.

  4. Boost Control

    The boost control is closed loop on the Power FC. The boost control routine is very similar to that of the original Super AVC-R. As for fuel and ignition mapping, the Power FC with the factory MAP sensor can support up to 1.2 kg/cm2 (17 lbs). As long as the unit is tuned, the Power FC will support any boost level up to 17 lbs. If you have the Apex MAP sensor, or optional Boost Control Kit, then the Power FC will support up to 2.0 kg/cm2 of boost or 29.4 lbs.

  5. Idle

    It will control idle under ALL possible conditions. Remember, the Power FC is capable of absolute perfect driveability. It has three idle speed adjustments:

    1. A/C off, E/L off (Electrical Load)
    2. A/C off, E/L on
    3. A/C on, E/L off

    also, for better driveability:
    adjustments of deceleration fuel cut recovery RPM:

    1. A/C off, E/L off
    2. A/C off, E/L on
    3. A/C on, E/L off

  6. SMOG legality

    The Power FC is not smog legal. It will never be smog legal for the FD. It is to be used only for off-road and off highway purposes. However, it does control all smog devices except for the EGR. Please do not ask any furthur questions about smog legality. Unfortunately, there are not enough FD customers out there to warrant CARB exemption and integrate the cost into the current price.

  7. Cost

    The unit currently costs $980 for the Power FC and $350 for the FC Commander. The optional boost control kit costs $380. I say currently because there may be a price increase in the near future. Please don't ask me how much because I have no idea.


Date: Tue, 18 Apr 2000 10:45:50 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

I forgot a question:

Q: Error Trouble Codes

A: The FC Commander has a diagnostic screen that shows all functions of the engine control system. The factory diagnostic system is no longer used because we've taken diagnostics to a higher level.

Here's what the screen shows:

This screen will show you if anything is the matter or simply just what's going on.


Date: Tue, 18 Apr 2000 18:30:07 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

Power FC answers:

English Instructions

Yes, the English Instructions are out. I believe that the retailers will be sending them out to all those that purchased them. New units will include the intructions.

Data Port

The PC link/datalog port uses the same port as the commander. It is a simple PS/2 mouse/keyboard plug. If you guys want to hack away at it, go right ahead! I'd be interested to see the results.

Knock Control

There is no knock control. Only monitoring. J&S ?!?! Good tuning will never result in knock.


Date: Wed, 19 Apr 2000 11:01:22 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

Power FC answers:

Cost of MAP sensor

If you purchase the Boost control kit, the MAP sensor is included. If you bought everything, it would be $1710. However, the benefit of the Power FC is that your car does not have be down for a week to wire up the Haltech or the MoTec. It will be down for approximately 10 minutes.


In the 8 years that I've been tuning high performance engines, I've never had a bad tank of gas. I'm not saying that it's impossible, but just very very very very rare. Yes, my confidence remains behind my statement: Good tuning will never result in knock. There are some other stupid factors like a poorly designed fuel pickup, clogged filter, etc that could cause fuel starvation. If your car has been built and maintained by an experienced and reputable shop, then these stupid factors will not affect you. As for rotaries being more sensitive, this is true. I've had my share of blowing engines when I was younger. I've been a rotary enthusiast/builder since I was 16. I have 1-82gsl, 3-turbo FCs, 1-FD. I've never required a J&S or knock sensor on any of these.

Oil Metering

We reverse engineered the the oil metering pump operation of the stock ECU. It is load and rpm sensitive. Please do not ask for this information as I cannot share this.

Sensor default

Yes, the Power FC operates in a fail safe mode when a sensor has failed. You can find out exactly which sensor under the Sensor Check screen in the ETC. menu of the FC Commander.

Laptop Software

This was not my department so I informed the marketing guy about the incorrect statement that laptop software is available. This will be changed shortly. Sorry for the misrepresentation.

I understand the Power FC may not suit everyone's needs. Please remember that the Power FC is more of a rom tuned ECU or PMS competitor and not a MoTec or Haltech competitor (although it has as much if not more tuneability than the Haltech). For $980 for the Power FC and $350 for the FC Commander, you cannot get more bang for the buck. The Power FC is a truly engineered ECU that is meant for the street, but good enough for the track.


Date: Fri, 21 Apr 2000 12:03:22 -0700
From: "Eric Hsu" (dailo502@hotmail.com)

Automatic Trans

For the gentleman that inquired about the Power FC for the use with Level 10 transmission, I talked to Koji at XS Engineering, and he said that they could probably help you out. I'm sure ray at SR could help you out too. Anybody that understands fuel injection thoroughly and has a Mazda repair manual can probably help you out.

Power FC with aftermarket turbo

The Power FC works with any aftermarket turbo. In the case of a single turbo with an external wastegate, the Boost Control Kit is necessary to control the external wastegate. However, if you already have a boost controller (avc-r, evc, profec), then you will not need a Boost Control Kit.

Power FC vs. AVC-R pressure sensor

Alfred, I believe your pressure sensor on the AVC-R is wrong. We've had two or three claims on bad pressure sensors (Out of over 3500 units sold), so we do not rule out the possibility of defects. Give the sensor back to your local dealer and we can give them a new one from there. We do not deal with warantee claims with end users.


Date: Fri, 30 Jun 2000 15:23:33 EDT
From: CCarlisi@aol.com

Hey guys, I received my FC yesterday and decided to give Eric a call to get the real story on the base maps before installing it. I spoke to him directly today and here is what he said. The FC comes to the US setup for 92 octane gas and tuned to run with a dp, catback, intake, intercooler. He mentioned that the base maps will work fine (WITHOUT ADDITIONAL TUNING) as long as the main cat is retained and the boost is kept within the limits of the stock control system. I also mentioned to him that my computer came with Japanese instructions, he said that this is normal and doesn't mean it's a Japanese version.


Date: Thu, 25 May 2000 10:04:23 -0500
From: "Rick S." (shev@pdq.net)

I have had my FC installed for about 3 weeks now. I upgraded from an XS Engineering ECU. Like others have previously mentioned, I too noticed many improvements over an upgraded stock ecu. First off, the 3k stumble is gone completely. I mainly experienced the stumble while the car was coming up to operating temperatures (130F-150F). The stumble was quite severe at times. It is interesting to note that by the simple install of the FC, my stumble completely disappeared. This fact reinforces what many suspected all along. The ecu logic is what is responsible for the stumble. Of course there are outside factors such as a weak battery and poor grounding, but many on the list have addressed these issues to no avail. It appears that the 3k becomes more profound as more upgrades are added. Some people claim to have no stumble even with upgrades, but I have personally driven some of these cars and have noticed a differing degree of stumble on different cars. It may appear as a flat spot on one car and a wild bucking bull coming out of the shoot on others cars. It appears as we lean these cars out with our upgrades, this is when the stock or upgraded ecu have a problem in the 2-3k range.

I noticed a slight problem right after installing the FC. I had a slight hesitation at 3k, not a stumble but a hesitation. This only occurred while in the 130F-165F range. I was able to increase the water temp correction map slightly and it cured the hesitation completely. The warm up characteristics are fantastic now compared to my previous ecu. The car starts more quickly than before and idles perfectly all the way through warm up. The only other problem I noticed was a slight fluttering or fast throttle pulsation feeling in the 2-3k range. It was not major but noticeable. I was able to use the Commander to increase temporary fuel map parameter from 1.00 to 1.066. This cured the fluttering problem, however the map I used to adjust this is a temporary map that will revert back upon shutting the car off. The permanent answer to this is to go into the 20x20 fuel map for adjustment. Adjustment of that map is a little more difficult. I am trying to become more familiar with that map before making adjustments to it. I am using the Ghost Trace to help track the exact map field to adjust. There are 400 data points for that map alone, so I don't want make any adjustment to it just yet.

I have owned a Haltech and now the FC. I can say that the FC is really starting to grow on me. It was rather difficult to understand in the beginning, but I have experience with the AVC-R so moving around the menus on the FC are quite similar. I have not had a problem with the small display. It works better for me than trying to look at a laptop screen when I had my Haltech. While driving it is easy to view the Commander display to see sensor readings. I set up peak hold as well as real time sensor readings.

The Ghost Trace is a real slick feature. While driving, you can see a 2d map with a 20x20 grid and a flying cursor that moves across the grid. It you have a trouble spot in a certain rpm you can drive the car into that range and view the point where the cursor is on that grid. That will be the map that being used at that time. You can then go into settings and change the value for that specific location on the map.

One other thing I noticed is my boost readings show a .09 bar difference between the AVC-R which has its own map sensor and the FC which uses the stock map sensor. I did notice that the pressure signal source for the map sensor is not the same. The AVC-R is sourced at a different location on the upper manifold than the stock sensor. I suspect it is just a slight difference between the sensors. It would be nice to know which sensor is correct and be able to get them to measure the same.

Overall I am really quite please with the FC. I can say however that it is very difficult for a tuner to deliver an ecu tuned perfectly for every car. Not every car is the same. Even providing a tuner with a list of your mods is not a sure bet that everything will be without flaws. Ray tuned my FC. I can say that the additional money spent buying from him is money well spent. He did a fantastic job with the initial tuning and has and will continue to support products he sells. He has field numerous calls from me and has answered many questions about fine tuning my FC even more.


From: Steve Cirian
Date: May 25, 2000

I still am not sure about the computer causing the 3K hesitation. I do not disagree that the FC or other aftermarket computers can cure it, but I am not 100% convinced that the computer is the root cause.

My reasoning is that if a car had no 3K hesitation to begin with, but it developed over time, then the computer's programming would have had to been changed for it to be the root cause. I am pretty certain that the programming is static. (I know about the 20K break-in switch, and have heard from several people that the hesitation developed before 20K miles.)

For more details, see the 3K hesitation page.


Editor's note: Ian Saul provided me with information on a Power FC mailing list. The list's address is:


Drop them an email and I am sure someone there will mail you the complete instructions on how to get signed up to participate.


Editor's note: this is the unit that PFS sells as their PMC. i think PFS does some tuning on it and sets it up for out of the box use on the '7. See the notes on the PFS computer for more details. --Steve


Date: Fri, 21 Jul 2000 10:20:30 -0400
From: "Wade Lanham" (walanham@mountaineergas.com)

>Not to interrupt, can some one give a good pros and cons about the EFI PMS
>and it's tuneability? My friend with the Eclipse seems to keep always tuning
>everyday..he can't seem to settle to one tuning program. Why's that?

As far as why he always retunes his PMS, it could be anything. He might just likes tinkering. Maybe he doesn't know how to get it tuned correctly in the first place. You should ask him why he always tunes it. :)

** There are some disadvantages to the PMS:

For 3rd gens, the temperature compensation is not implemented. Doug indicated that I am the only person who ever asked for that feature for an rx-7, so there's no chance of him doing it (unless others want it too, of course).

Since the standard setup of a PMS is to add/sub fuel on top of the stock ECU's maps, there are problems associated with that. For instance, the 3k hesitation found on many rx-7s can't simply be tuned out with the standard PMS setup because the problem lies with the stock ECU.

The windows software has several small bugs (annoyances). Nothing that makes the software bomb out, or anything serious, but it makes you wonder where your money went when you keep getting errors when using it.

** In defense of the PMS (since Gordon gave a pretty good argument why NOT to get the PMS) I should mention a few things (pros) that you might not know.

With the windows software, the pms can be set up to continue running piggy-back mode, but with higher resolution than with the keypad. All maps have 500rpm resolution. The partial throttle map expands to have 10 partial throttle loads. The Boost map (additive to whatever other maps are currently active, be it partial throttle or WOT) has 5 load levels (between 1psi and the Max boost configured). I think having this level of adjustability is pretty complete for those who want more than just some general richening with the keypad.

Additionally, the windows software allows the PMS to run in stand alone mode for fuel and ignition timing. This means that the PMS will completely ignore the fuel/ign the stock computer tries to command. Running in this mode will eliminate any problems associated with the stock ECU, like the 3k hesitation found on many RX-7s. Also, resolution is even finer - offhand I think it drops to 60rpm increments, and load divides as well (how much finer I'm not certain). Running in this mode would put the PMS in the same ballpark as other stand alone systems like the PowerFC or Haltec. Another person and I are playing with this feature when time permits, so I can't give a full report of how well it works yet.

The windows software offers some sufficient data logging capabilities. Data included is injector duty cycle, o2 voltage, fuel ms, water temp, intake air temp, TPS position, and a few others (that aren't as useful or are computed values). Playback shows which map cell the car was in at the moment, which makes tuning pretty easy.

The PMS is the only computer that I know of that can be as simple as a pre-tuned plug in (for those who didn't buy the keypad), add the keypad and the user can make some moderate adjustments to grow with his bolt-on mods, later purchase the Windows software for more serious tuning with datalogging and finer adjustments for the moderately modded car, and even run full standalone for the totally wild car. There are other computers that can do each of these things, but who wants to start with an $800 stock replacement ECU, then sell it for a $1200 Power FC, then later sell that to get a $1500 Haltech?

In my opinion, the PMS is an excellent system, but like any system, it must be set up well to perform well.

I might consider the Haltech at this point for myself, but I don't know enough about it, haven't driven a car with it or used the software, so I'm not "sold" on it yet. And, I still haven't reached the point where the PMS won't work for me. But I wouldn't recommend a Haltech for someone with a couple of bolt on parts who needs a little fuel enrichment at WOT. It's just not worth the trouble.


Date: Wed, 21 Apr 1999 18:01:15 -1000 (HST)
From: F8LDZZ

Blitz DSBC

Advantages:  *dual RPM boost levels
Disadvanatges:  *NOT closed-loop operation


Date: Tue, 30 Nov 1999 15:08:34 -0800
From: "ari" (ari@rampageusa.com)

I have a Greddy Profec Fuzzy logic boost controller. After many months of headaches and inconsistent boost, I spoke with a Greddy rep who told me that the fuzzy logic boost controllers do not work properly with sequential turbos.

A lot of people on the list use the Greddy Profec B (the cheaper one of the two) since the low tech setup seems to work better than one which uses "logic" to learn boost curves.

This makes sense since the boost spike and second turbo activation can not readily be "learned". The fuzzy logic controllers (at least the one that I know of) do not have an RPM input, and can't cope with the spike and transition.


Date: Thu, 18 Mar 1999 10:03:01 -0500
From: Tom Walsh

Profec B:

I use the Profec B in my car and have not had a problem, but as related to the previous discussion, it is pointless to have it unless you have an aftermarket ECU that will allow you "turn up" the boost levels. Without the upgraded ECU you make it easier for you to hit the fuel cut (which would be bad).

With a modified ECU, it is nice to have, because with a push of the button you can run a preset level of boost. I currently have mine set up to run 10lbs of boost on low and 12lbs of boost on high. This actually allows you run 3 different levels of boost. With the unit off, the spring on the wastegate takes over which opens at 7lbs of boost (good for breaking in a motor), then with the unit on and set to low you can have 10lbs of boost and with the touch of button switch to high and run 12lbs of boost.

Greddy also makes a remote mount button that is used in conjunction with the Profec B that allows you to remotely switch between high and low boost levels. A nice feature for me as my Profec B is mounted in my glove box (I like a stock interior look).


Date: Tue, 30 Nov 1999 08:02:13 -0600
From: "Westbrook, Chuck E." (CWestbrook@tmh.tmc.edu)
Subject: RE: (rx7) [3] Manual vs. Elec boost controllers

A couple of years ago, I had the older version (purple) of the PFS PMC. Once it learned the boost pattern, you had to turn "boost learn" off. When the temperature changed greatly, so did the boost. Even mods would change the boost. The new version is suppose to be able to stay in "boost learn" mode all the time and thus should be boost stable.

The Greddy Profec B, doesn't keep boost stable either when the temperature changes.

To be temperature boost stable, the unit would need it's own internal "map sensor/pressure sensor" and trigger off the voltage for the boost selected. I think only the HKS units have this, but I'm not sure.

All of these only control the wastegate. You would have to use the Knight Sports system if you also want the pre-control system regulated.

I currently use manual valves on both the pre-control and wastegate. This controls spiking well but is also temperature sensitive.


Tri-Point uses an Electromotive unit on their National Champion A Street Prepared autocrosser. See Electromotive's Web page for more info on the box.


From: Gary Meisner (GSMnow@aol.com)
Date: April 22, 1999

I run the Electromotive TEC II with Super Blend 2 software. I don't use the blend feature, but the rest of the improvement make it well worth while. The data logging is fast, and it give live pulse width info the older software could not. I will have my PC at the first event if you wanna look at all it can do. they sell a slightly different version for the rotaries. I think it is due to the ignition differences.

>I really ought to get the knock sensor soon. I have heard good things
about the J&S. Which one are you using?

The TEC II has built in knock sensing. Use a GM knock sensor tell it at what noise level to start retarding, how fast, how far, and when the knock stops, how fast to bring the timing back in. All done on the laptop.


Date: Sun, 09 Jan 2000 21:40:00 -0500
From: Bryan Smith (r0t0rhead@earthlink.net)

Haltech and Electromotive make very capable systems and both have been used successfully to improve rotary engine performance. I know, I've set up both systems on RX7's in various states of modification. The fact is each manufacturer chose a different method to achieve their goals. Which is better- that's a matter of opinion and like most people I have my own.

Given the choice between the two I would go with the TEC-II. (snip)

The TEC utilizes a different approach to determining injector pulse width than any other system on the market. Your reference to the TEC-II's VE table as an 8X8 fuel map is simply inaccurate. The VE table allows the tuner to adjust the basic fuel map to compensate for the engines different fuel demands at tuner specified load points. The fact that all of these points are adjustable both for load and rpm allow infinite adjustment of the fuel curve.

Consider the other methods where you are constantly adjusting individual maps and relying upon the computing speed to determine pulsewidths and corrections- its like scratching an itch, they require input before reacting. Yes the TEC requires a little more effort to tune and utilize the superior ignition system-but the crank trigger wheel is not difficult to mount and once air gap has been initially set, your done with it. Add in the datalogging feature which aids tuning, the General Purpose Output Table which MAY be used to activate the oil metering pump, nitrous solenoids, or control the turbo's wastegate, and you can see how the additional cost is justified. Consider either system as a tool - I prefer Snap-On to Craftsman. Yes MOTEC is superior but then for $10K you get what you pay for. BTW Electromotive will be introducing a higher level unit to compete with MOTEC in the near future-and at a more reasonable price.


Haltech has been mentioned by several people on the list, but I don't know if anyone is currently using one of their units.


Date: Tue, 25 Nov 1997 07:32:26 -0500
From: Carlos Iglesias (rotary@mediaone.net)

>I know basically what's out there. But, is there a
>computer that is HIGHLY programmable? I mean, curve
>function setups on all the systems. What I mean to
>say... Is there one that I can program so PRECISELY
>that it runs just they way I want (or as close as
>humanly possible)?

Programmability is just like speed: How fast (programmable) do you want -> how much do you want to spend.

Download the software for a first hand look at the programmability of these two $$$ standalone computers:

A hREF="http://www.haltech.com.au/">Haltech: about $2200 & replaces all major engine sensors.

Motec:about $3900 & replaces only the one engine sensor.


Date: Tue, 25 Nov 1997 18:30:08 -0800
From: Trey Cobb (trey@rx-7.com) (of Rotary Performance)

We've had very good luck with the Haltech units. The E6A is typically what we've been using on a few cars around here. Since Haltech of America is located just down the road from us, it's been easy to get the technical support and reliability of the units is top notch. Plus, you can program it with units that most people understand instead of time on gamma or whatever, but then again I think I've just been spoiled by looking at pretty bar graphs. Damn I'm lazy. ;-)

You are looking at a little over $2000 to get the system, plus you'll need a laptop to do any real time tuning but it'll let you dial in almost everything you want.

If you want info on Haltech, you can call Del Barnett at 972-831-9800. He also helped tune on Andy's RX-7 and I think even has a rotary he's building up myself so he's extremely rotary friendly.


Date: Thu, 19 Mar 1998 15:22:21 -0600
From: "Kevin Tan"

A number of you have asked how much it would cost for the Haltech .depending what you want with it, its average to say they go for approximately go for $2500 for my setup. including the pump, maps, harnesses, software and everything you need for the install it. Install just started...dont know too much bout it yet.


Date: Mon, 10 Jan 2000 07:33:55 -0500
From: "Karagiannis, Demetrios Mr ODCSINT/GD" (Demetrios.Karagiannis@hqda.army.mil) (snip) I am not saying the Haltech is better then anything I am just going to give the reasons why I chose to use the Haltech over the Electromotive wich I was considering.

1) A Haltech can fire injectors multipoint, sequentially, staged, or batch fire.

2) 22 fuel ranges, every 500 RPM to 10,500 RPMs with 32 load points per range

3) 22 ignition ranges, every 500 RPM to 10,500 RPMS with 32 load points per range

4) Useful correction maps for fuel and ignition such as Coolant temperature, Air temperature, barometric pressure

5) Great data logging

6) Installation was not difficult and the directions and support I received was awesome from both rotary performance and Haltech.

7) I cannot say enough about how easy the software is to use.

8) The leading and trailing sparks are generated separately with a programmable split.

I do understand that some tuners may prefer the TEC-II but many like others prefer the Haltech for example Rotary Performance http://www.rx7.com and most of the 7sec rotary powered cars in Puerto Rico http://go.to/puertorico hopefully this answered some of the questions I recieved and if anyone one would like more info or details on how the install went I would be glad to help.


Date: Sun, 9 Apr 2000 17:19:25 -0400
From: "Ryan Schlagheck" (ryan.schlagheck@worldnet.att.net)

Just wanted to let the group know that Demetrios and I successfully installed a Haltech E6K into my personal ride this weekend. We essentially worked on the car for four hours Friday night, and 14 hours on Saturday. On Sunday (today) we tuned! Demetrios (The Haltech King) was the instrumental part in making sure the install went smoothly while not having to do/re-do things...the benefit of experience to be sure! I want to publicly thank Demetrios for all of his help soldering and crimping, making the long drive down and back, putting up with my chatter, and his baseline tuning input. A special thank you goes to Trey and Ari at Rotary Performance in Garland, TX for the Haltech, installation notes, diagrams, and basically great service both in-house and over the phone. The Haltech/RP deal is possibly the best vlaue going in a fully programmable vehicle ECU.

Not only that...this is perhaps the finest moment for me and my 3rd Gen for the following reasons:

  1. We turned the key to "power-on" once everything under the hood was connected and the associated plumbing (IC, intake) was put back on...and the Haltech software on the laptop recognized _every_single_one of the vital sensors needed for this installation.

  2. The very first time we went to start the car, it started right up without even a hesitation. The car's idle is rock solid.

  3. The Rotary Performance E6K terminated harness cuts out a boatload of hours of sorting, splicing, and generally prepping the harness for installation.

  4. Expletives like holy $#!t and sonofaB!+(# were actually used to express happiness, surprise, and satisfaction rather than disgust and despair! :-) That's a great feeling.

Driveability is excellent around town and WOT runs on boost are smooth. Oh, and no 3k hesitation. :-)

There's more to come once I get the tuning all squared away. Next on deck is the proper wide-band lambda O2 sensor for more accurate tuning and datalogging.

This weekend was a great weekend. Thanks again to the folks at RP for their great customer service, and to Demetrios and Kerry Karagiannis for the company and tech support over the weekend.


Date: Tue, 11 Apr 2000 00:22:11 GMT
From: skan@ticnet.com

Haltech can be configured for choosing what O2 sensor you want to use for your car. My lambda unit has an output port where I can tied to the haltech and configured the haltech to read 0-5V range from the unit and still be accurate. You can simply choose Bosch 0-5V O2 sensor and tied that to your car without the lambda meter. The only problem is that you'll have to convert a/f ratio into voltage. I believed at 12:1 ratio, the voltage is around 78V for 0-1V range so basically you multiply that number by 5 for 0-5volt range and it should be the same.


Date: Tue, 11 Apr 2000 14:43:19 +0000
From: ryan.schlagheck@att.net

You have to run a premix for the E6K and E6S. The OMP runs at 50% without the OE ECU so you make up the rest with a 2-stroke premix.

The RP terminated harness saves a lot of time and confusion. You don't have to mess with which wires go to which sensor. And, if you want to use the stock Charge Air Temp and Water Temp sensors like I did, you can cut, connect, and solder the Haltech harness to the sensor. For a clean installation however, you can drill and tap the stock Air Temp and Water Temp sensor locations for the Haltech sensors (included in package).

RP provides base maps for use with the E6K and E6S. The maps are based on your mods and are understandably rich to start off with.

The RP terminated harness for the E6K plugs into the Haltech ECU. You lose the stock ECU and two of the four ECU connectors (goes away with the stock harness). There are four wires you tap in to on the remaining two ECU plugs inside the car.

I'm running non-seq, but RP has these installed on sequential twins. However, it's likely that the majority of people using the E6K have, or have plan to run beyond the capabilities of the stock turbos w/ a single turbo (most people are able to overrun the capabilities of the stock turbos with an ECU, DP, MP, Intake, and Exhaust!). I guess what I'm trying to say is that you could simply run an additional injector controller for less $ and not have to mess around with the harness removal and Haltech installation. Also, the PowerFC is able to take injector size changes and can be programmed to meter them for proper flow. For running the stock turbos in seq trim, these are probably more viable than a complete ECU replacement.


From: Justin Kearns

I am not a Wolf specialist so I will keep it to the things I know The Haltech gives 32 load sites per map and a map every 500rpm...the Wolf does not have this resolution (this is actually 4 times the resolution of a wolf...plus then the correction maps as well...as you can see this is a far more tunable system)

The Haltech also has multiple correction maps that are all user adjustable For rotary applications the Haltech allows the traling split to be adjusted..(I am fairly sure the Wolf is fixed at 8 degrees split timing)

The Haltech will support the factroy coil and ignitors from your turbo II (these require a unique signal to drive them) as well as the factroy crank angle sensor.

Yes the Haltech can do turbo timer and boost control as well as the following:

If you were to get a Haltech I can supply a map that will get you up an running.

It is actually ineresting that you ask this question as I had actually been responding to another guys mails that was doing the same thing.....Unfortunately I have removed that by now so I cannot send it to you so you can see the wolf guys response..

If you would like to get a hold of this if you contact a freind of mine at www.hitman.hm (his name is Matt) he will have it on record I would imagine for just such an occasion..

Either way if you want to talk to someone that has used all of the different brands and can give more feedback to you just drop him a line....tell him I sent you.

As for security features the Haltech memory is non volatile.....this means the ecu can be removed from the car and it will not lose its settings...you want security,,,unplug the ecy and take it with you and the car is going nowhere.

If there is anthing I have missed or anything more that we can do for you please let me know.

Kind Regards
Justin Kearns
Haltech Tech


Date: Mon, 25 Sep 2000 16:29:21 -0700
From: "red-rx7" (red-rx7@home.com)

I have the sequential twins still running with the Haltech. Works great. I like to have the ability to change when the second turbo comes online. It actual makes more power overall and less initial power when it does become active when set to 400 rpms earlier. The dyno sheets are interesting.

It's not the easiest thing to setup though. A relay is what controls when they work / when they don't.


Date: Mon, 12 Jan 1998 22:27:37 -0500 (EST)
From: Fritz McKellar

As for ECUs, I think XS upgrade kicks ass, they are the only place (to my knowldge) that rid of the 3K hesitation, they are cheaper than Pettit's (and free chip changes), and the thing works. I'm still amazed the the power revealed by this upgrade. My car has run quicker MPH times than many Piggy back systems (read Farrel) with similar mods, and that was with no practice (expect 12.5 @ ~115-116MPH this spring, still using the stock block with 50,000 miles on the mods, and and 94 octane gas, oh - and street tires). That ECU gave me the 114.3 trap speed (along with my front mount IC ;-).


Date: Wed, 14 Jan 1998 11:56:30 -0500
From: Tuck

Isn't that computer modification (XS) the exact same thing that Pettit sells, the Techtom upgrade? I think you're just looking at different resellers of the same computer equipment.


Date: Wed, 14 Jan 1998 19:08:42 -0500 (EST)
From: Fritz McKellar

No, XS does their own programming (one day turn around), heard Pettit uses some guy from Japan (come over every couple of months), so all Pettit's ECU upgrades, and chip upgrades are pre-fab, and not 100% customizable to maps that you would like. XS adds a new board to accept the chips. You can specify the ignition, boost, and fuel maps...


Date: Mon, 19 Jan 1998 16:45:21 -0800
From: "Hung-Jen Hung"

Just confirmed with Eric at XS engineering. He said the Tuning ROM they use is actually from Tech Tom which is same as G-Force and Pettit Racing, but they do their own programming not from G-Force. He showed me that Motec air fuel ratio meter and the laptop they use for programming, so it should be true.

I mentioned our mailing list to him and he kindly offered us a special deal on XS Tuning ROM. The regular price is $695 and the price for us is $660. Does not sound too much difference, but the original price is cheap already so I didn't ask him more.

If you are interested, just mention this mailing list and he will give you this special deal. The phone number of XS engineering is 714-992-4133. BTW, I do not make any penny on this, so please don't question me.


Date: Thu, 29 Jan 1998 19:17:36 -0800
From: "Hung-Jen Hung"

XS engineering, 714-992-4133. If you had any question, you want to talk to Eric. According to them, 95% of the hesitation problem will be gone. If you are buying, don't forget to mention this mailing list to get a discount.


Date: Fri, 30 Jan 1998 07:47:31 -0600
From: Richard Sheveland

Has anyone with an XS computer upgrade done a dyno run to measure output? I would be interested in seeing a dyno sheet if someone has one posted on a webpage. I am finishing up some fine tuning before taking my car to the dyno.

I have recently installed an XS computer upgrade (unlimited) and was quite impressed with the smoothness. I have noticed that my 3k stumble has disappeared completely. I had thought that I might have had a grounding problem before. The overall driveability is outstanding for a car with full exhaust, intake and IC. My idle is very smooth.

I have heard that the mapping on this computer is a bit richer than Pettit's computer. I would suspect the potential power output would be higher for the Pettit. Both Pettit and XS are very good choices from what I have heard and seen. I just decided to try XS.


Date: Mon, 26 Jan 1998 22:09:54 -0800
From: NetBlazer

I have nothing against XS, and they have always been very helpful on the phone, and the bottom line is I don't reccomend not buying from them, and have heard mostly good things about them. However:

A couple things:

I have pulled apart both Jim's Mostly Mazda upgraded ECU, and my dad's (also Jim) Mostly Mazda upgraded ECU, and recently a friends XS upgraded ecu. On both of the MM ones the desoldering of the microporcessor was done very well, and the soldering of the DIP sockets was also done very well, in fact it looked almost as good as the org. wave soldered board.

When I opened the XS one I got scared, the desoldering didn't look like it went too well as the microporcessor pins had extra solder/pieces of trace all over them. Basically didn't look like it had wanted to come free of the circuit board as if they had heated/desoldered one pin at a time instead of having a tool which does all at once. If I was to have bet on whether the cpu even worked (over heated IMO) at that point I would have put my money on not.

The soldering of the DIP was not very nice either (potential cold solder joints), and the circuit board had gotten a little toasty (most likely from the desoldering ).

I don't know if this was an isolated case, as I have only seen one by them, and it did work plus they do stand behind their product. Although it is quite a bit cheaper for the same basic Tectom upgrade, I personally would not trust my engine management to anything that had that type of soldering done to it, as harsh vibrations are not foreign to a race vehicle. You will have to decide if the extra ~$150 is worth peace of mind.

The actual maps may or may not be better one way or the other. I have no real info on that other than some things XS said on the phone concerning the limitations of the stock fuel system (or lack of) which I fully disagree with, as does MM.

Also the extra EPROMS at that time were $100 (4 months ago), which still leaves 'free' as a pretty good deal :)


Date: Fri, 6 Nov 1998 11:15:09 -0500
From: ryan.schlagheck@unisys.com

My stock ECU was upgraded by G-Force Engineering (Torrance, CA) in May 1998. For what it's worth, I chose to have my own ECU upgraded, instead of doing a core exchange, so it's a '94 computer, upgraded with new maps. You can call me at (919) 954-2234, or talk to Robert @ G-Force (310) 782-8278 for more information and detailed specs of the program.

The G-Force ECU fuel and ignition maps are set up for the basic performance upgrades: downpipe, midpipe, aftermarket cat-back, and cold-air intake. I consistently ran 12.5-13.5psi on stock motor/turbos. Purchased new for $660 + overnight shipping both ways for $70.00. Selling for $600.

Wolf EMS

Date: Wed, 4 Nov 1998 10:28:07 -0600
From: "Ryan Scott" (turbo@nothnbut.net)

I have the official Wolf Engine Management Systems homepage up. On it you will find info about all the products Wolf EMS offers, including the Wolf 3D and Wolf 2D stand alone engine management computers. It is a work in progress, so products that don't have detailed info yet will have soon. But don't associate "Work In Progess" with a page that looks like crap with dead links and no info. That is definately not the case here, the page is well worth your time to check out.

Also, within the next few days there will be articles from Fast Fours and Rotaries comparing the Wolf system with a Haltech system, TEC system, and a few others. Coincidentally, the Wolf system came out on top. And it's price is the lowest of the group also. I don't sell these products, but I have one in my car. I'm also convinced that if you're own a rotary, and are in the market for stand-alone, the Wolf is the best solution.


Date: Fri, 4 Dec 1998 10:41:50 -0500
From: ryan.schlagheck@unisys.com

I've spoken to Michael Gurgainers, who is repping the Wolf 3D system (at least the 3D for the FD, could possible use the 2D in 1st and 2nd gens???) in North America.

The bottom line is that this system is much more advanced than the Haltech, cost less than the Haltec ($1600), replaces the ECU and wiring harness, can support memory cards ($20) to run different configurations, and is one badass piece of hardware.

I was going to submit my car for the first North American 3rd Gen guinea pig to get this mod, but I chickened out because I am getting a $6000 overhaul of my motor + some other goodies. I didn't want them to blow a perfectly good race rebuild while tuning the Wolf to my car. Wolf has tuned several 2nd gens. I will however become more interested in getting the Wolf3D once they have fine tuned the maps on someone else's 3rd gen.

I'm interested because of it's flexibility over modded ECU's (which someone correctly noted were static) despite our collective propensity to bolt-on more go-fast goodies, and it's purported simplicity over the PFS in tuning the fuel map when running a beefed up fuel system and larger injectors.

The memory cards - much like Sony Playstation memory cards - can be "burned in" with different configurations. I'll take three (1) for the dragstrip (2) for the track (3) for emissions testing. In addition, I think that you can also retune the memory cards, so "burn in" is the wrong terminology, I should have said "write-to."

I've mentioned this system to Cam at Pettit about a month ago, because Wolf is looking for qualified installers of the system. I don't know if Cam has done anything about it yet though. I can't think of a better shop to handle the tuning though (well, PFS, but they already have the PMC at that price point.).


Nick sells the Wolf 3D unit:

Date: Tue, 3 Aug 1999 11:26:35 -0400
From: "Nicholas Riefner" (racin@worldnet.att.net)

The Wolf 3D system is a full replacement computer, not a piggyback. It has a starting price of $1425.00 for the base system, so it is also not nearly as expensive as you quoted the stand alone systems as being. It currently controls timing and fuel, with the incorporation of a boost controller in the works. It also has provisions for a turbo timer option that is programmed right from the hand controller unit. This is nice because it means you don't have to find a spot to mount another control box in the car.

There are certainly many choices available to us for engine management control. It all just depends on your needs and how much control you want over it.


Date: Sat, 18 Sep 1999 22:28:47 -0700
From: "Carlos A. Iglesias" (rotary@san.rr.com)

Back in December, I picked up a Wolf 3D from my friend Nick, at N-Tech. At the time, the 3D had just come to the States from Down Under, and Nick and I were the among the first to install the system on FD's. We worked together to figure out ALL of the wiring. Though I was the first to get it up and running, I had also rebuilt my engine so it was a while before I got to use it above 7000 rpms. During the next couple of months, I refined my maps within low rpm/boost settings and waited unitil I felt comfortable to start upping the rpms and boost.

Well, long story reasonabley short, the car was sputtering and cutting off above 6500 rpms. The cars "vital signs" included very high EGTs, but sufficient fuel to maintain O2 levels in the .88-.94v range. This didn't make sense. Whenever the car sputtered, the EGT would SKYROCKET, so I would back off. This made me think that there was some sort of ignition related misfiring. I thoroughly troubleshoot the ignition system unit I ran out of candidates. So after many months and thankfully not as many dollars, I call Down Under and spoke with Steve at AEM (Wolf's parent company). He asked several questions about timing, and set me on the righteous path to engine management enlightment.

Today, I finally won the protracted war. It turns out that I had miscalculated TDC, and had modified the stock timing wheel with the wrong TDC. I should have just physically calculated TDC instead of trying to deduce it from the factory manual's Engine Electrical section. My calculations for the timing wheel had been retarded 26 degrees! So for most of my ignition maps, the actual ignition was occuring A(fter) T(op) D(ead) C(enter) as opposed to BTDC. It's no wonder the engine was sputtering at higher and EGT was going through the roof. The a/f mixture was still burning on the way out of the exhaust port.

So the reason for this post is that I've been witholding my opinion on the WOLF 3D until I was sure that my problems were not systematic of the Wolf. They were my of myown undoing, but the Wolf has been very impressive. Here are some of my impessions and comments:


  1. Great value! For a stand alone system, it's a great deal in the $1500 range.

  2. Excellent compatibility. The only stock systems compromises are:

  3. Extremely simple to install (compare to other stand alone computers) due to 2. above.

    Uses stock ignition system (major plus), triggers, relays, tach, and more...

  4. Very good programability. Every 500 rpms with each having 8 load points. Sufficient secondary adjustment fuel/ignition adjustments.

  5. I like the the design, interface and engine parameters display of the handset.

  6. Very good self diagnostics/indicators.

  7. By this post, Nick at N-tech (in conjunction with Spic Racing) will have maps for several different combinations of injectors.


  1. The logic for the injector staging is not as "useable" as I've seen on more expensive units. This results in only getting about 95 percent of the the total injector pulsewidth available.

  2. Poor data logging. Most values are only min / max values. O2 datalogging does a very nice job of logging every rpm/load point, but it only reads in 10ths of a volt, while fining tuning would require 100ths of a volt. Additionally, the datalogging software does not record "realtime" steams of data. I find this to be the weakest point in the system.

So after finally being able to blast around up to 8500 rpms today, I felt compelled to convey my "buyers joy" with the WOLF 3D. It's been a long time coming. Now I'll just need a couple of hour of open highway to tune it up to a "gentlemanly" boost level, and then we'll see what the dyno says. Hopefully I'll finally get this monkey that Dean Colver put on my back when he dyno'ed 389 RWHP early last year.. but by now I've learned that only time will tell.


Date: Sun, 19 Sep 1999 14:03:25 -0400
From: Jeff Smith (bureau13@mediaone.net)

You're running non-sequential, right? I've heard that, in addition to the lack of oil metering pump support, it doesn't work too well with the stock sequential system. My impression is that this thing is good for non-sequential or single turbo applications running premix, but not so good for more mildly modified sequential cars. No one comes out and says that, but its the impression I get...would you agree with that?


Date: Sun, 19 Sep 1999 11:11:13 -0700
From: "Carlos A. Iglesias" (rotary@san.rr.com)

Egg in my face! After running non-seq. for so many years, I've forget that this is the exception rather than the norm. Thanks for catching my major slip - as opposed to looking up it :-)


Date: Mon, 20 Sep 1999 23:17:03 -0400
From: "Wade Lanham" (wade@aeawv.com)

The Wolf systems don't control boost at all.

You impression seems mostly correct. The fundamental thing that Carlos probably should have mentioned (which really is obvious) is that it is not a plug and play system. It is, and probably always will be, a system only to be used by serious tuners, as opposed to the standard ECU replacement.

I'm not implying it is not a fantastic system (because it sure sounds like it is), but that it is not a system for your everyday person adding bolt-on parts.


It sounds like you have a great project going. Rotaries are great aren't they? We have quite a bit experience with Rotary engines and 550 to 600 hp out of a 13B shouldn't be problem if it is built correctly. With the Wolf 3D system you can do all of your programming from the hand controller or with either a laptop or home PC. The hand controller allows you to actually do in car tuning. This system allows you to use your stock TPS and crank angle sensor with only a slight modification. We can do staged injection so at 'low load' you can run on just 2 injectors and then as load increases throw in more injectors. On my own personal car (RX7 Turbo 2 w/REW 13B) I run total of 8 injectors and figure I am making about 500 hp. The system sells for $1206.00 + $40.00 shipping US. If any more questions please call 1-877-RACE-WLF 9-5 PST.

Joe Klokkevold


From: jwbontke@email.msn.com
August 17, 2000 01:00 PM

I have seen the Haltec(H) tuned at RP. Compared to my Wolf I have found that the wolf is easier to tune. If you worked with the Haltech long enough you would probably have no problem tuning it. Here is the only problem I faced. Everyone at RP who had a stand alone ECU used the Haltech because RP had excellent tech support and help. That makes a big difference. With the wolf I relied on a guy I met over the web who had one and he helped me plus the Wolf website and guys that worked there. If I lived in Pecos, TX, I would be out of luck. The system depends on who you have to help you. I am a Mazda tech(ASE certified) and know a good bit about most of everything. The rotary was a whole new ball game. I will not say one is better than the other, but after seeing the Haltech in action I still bought the wolf.


SDS was mentioned as a low-end solution - does not need a PC to program, simple to use, etc. But it does seem to be a "one-size-fits-all" solution - their Web page says it will work on cars, motorcycles, boats, etc.

J&S Knock Sensor

A knock sensor is an almost indispensible item for a rotary if you are going to modify it. One note - if you buy a high-end computer, it will probably include a knock sensor, so you will not need to buy a separate one (I am pretty certain the Electromotive does, and am guessing the Motec does too). --Steve


Date: Tue, 04 Nov 97 13:37:34 -0500
From: "Linthicum, Sandy" (linthias@sandy-ntws.usps.gov)

The J&S is a system developed, refined and improved over the last 10 yrs by John at J&S to detect pre-ignition and control it by dynamically retarding timing on each ignition cycle such that only the effected cylinder (rotor face) having pre-ignition (detonation) is retarded. The most basic setup for our cars consists of a highly sensitive Bosch knock sensor tied to a microprocessor control unit. The micro uses DSP (digital signal processing) to discriminate impending detonation from normal engine noise. It is progressive and dynamically retards the ignition up to 20 degrees in what are (if I remember right) 2 degree increments. The program is adaptive (ie. it learns as it goes). An option is an LED display that lights to show the amount of retard being applied and to let you know whats happening. It is also useful for setup, testing and tuning.

The control unit is installed such that it can intercept the ignition pulse to the ignitor or coil and delay it when detonation is imminent or in progress.

The factory ECU is handling many, many tasks and is far to slow to respond to detonation in time to save your engine. In fact, it is not fast enought to even control rise in modded cars. Nor does it have the discrimination ability to separate engine & drivetrain noise from pre/early detonation.. By the time the factory system detects anything and acts, your rotart engine is toast (may take a while but believe me, you will pay). Apex seals on standard 3rd gen engines are considered able (maybe) to deal with 3 - -4 detonations before permanate damage. With piston engines you have more slack but detonation if continued will result in melted pistons, broken connecting rods and hammered bearings. The J&S pretty much ensures that real detonation never occurs since it detects its onset and cures it up front.


Date: Thu, 25 Jan 2001 09:08:10 -0800
From: "David Lane" (dlane@peabody.jhu.edu)

Standard J&S set-up on an FD will include an occasional blip the first time or two you go under full boost--even if the water temp gauge says the car is fully warmed up. No one knows why this is. I get it on my car too. One might speculate that the first time a turbo spools up for the day, there is some kind of little rattle caused by some part of the engine that won't be up to temperature until it experiences the heat of a few max boost blasts.

Most people agree that any J&S retard during regular operation is a BAD thing. In other words, you should not be any lights at all under any kind of normal driving. For one thing, if you have a total of 10 degrees retard available to you, and you use up 6 degrees for daily running, you only have 4 degrees of room for the J&S to work with if it senses detonation. This is not enough.

Secondly, the value of the lights coming on as a warning is beyond measure. You are more likely to notice a light coming on when it isn't supposed to, than the addition of a single LED if the unit starts retarding 8 degrees when it only usually retards 6 degrees. I dare say, if you run the car that way, you have rendered the warning nature of having the display light up moot. This is a huge safety advantage to toss away.

The sensitivity control, as far as I know, is not "off" when rotated fully counter-clockwise. The unit still does its job that way, so I would not be afraid to back your setting off a little until you don't see any lights.

I have one of the original units, and after a few years with it, I have come to think of it with this philosophy: Actual detonation is nasty enough to trigger the unit even with the sensitivity turned to minimum. Thus, the sensitivity adjustment might be thought of as adjusting how sensitive the unit is to extraneous noises.

In other words, we think of the sensitivity adjustment as meaning "How sensitive do you want me to be in reacting to detonation?" Obviously, the answer to that would be "very sensitive." So we set the adjustment as close to maximum as possible.

It works better for me to think of the sensitivity adjustment as: How much general engine noise do you want me to filter out?" My answer is: "As much as possible." This leads me to a sensitivity setting as close to minimum as possible.

Given that the J&S has a special circuit to identify the "audible and percussive" characteristics of detonation, it seems logical that we can use the sensitivity adjustment to filter out most all other extraneous noises. For that reason, most of us seem to be running the units at relatively low sensitivity. Those I have corresponded with over the years seem to be running with the adjustment open only about 25-33% from minimum.

I hope this helps give some perspective to the question. If what I am saying is not supported with the experiences of other 3rd gen owners, please chime in quickly. I am making a logical argument here, but if someone has more recent information, or simply a different impression, it needs to be posted. Detonation is nothing to play with, and I don't want to be the cause of a costly mistake.

Cruise Control

Date: Tue, 27 Jan 1998 02:12:48 -0600
From: "Kevin Tan"
ok, i just removed mine, theres 4 parts to it.

The motor in the right hand corner of the engine compartment is the easiest to take off and no you won't need an additional bracket. The harness sits there waiting for the motor assembly to be plugged in and the motor screwed down. The last thing you'd have to do is to attach it to the throttle body (also constructed to take the cable on all models) this is the easiest part.

Located on drivers side, adjacent to the the fuse block. Now this i'm not sure if it has a harness already.....I'll have to pull apart Wyums car when he's not looking sometime to find out! :) Otherwise, the install of this unit is also very easy ....1 10mm nut and 1 10mm bolt.

This also is very simple to install with just one catch! ---> whoever buys this thing from me is going to have to switch steering wheels cos the non-cc don't have a hole cut for these switches. Again I don't know if there is a harness already in the car. ......guess i'll just have to rip out Wyums steering wheel to see....he's gotta be loving me by now but shhhhh don't tell him about it! :)

Located to the right of the tach. For all non-cc models you'll just see a black plastic piece to fill the hole. On cc models this is actually a switch to turn the thing on or off. This is the part i'm NOT including cos i don't have the time/ want to make the effort to rip out the dash. therefore this I don't know if it will have a harness already.

This should be it, currently someone already bought mine for $250 but if he doesn't want to switch steering wheels or if his is in really bad shape, it'll be up for sale again. I'll check up on the existing harnesses this week. Believe it or not, parts alone for this addition at a dealership is $750, .....what a RIP!

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