Using a 99 Clone ECU in a 91

[Alex3000gt]

I searched, and the information was pretty scattered. I thought it would be helpful to post all of the information in one place for people in the future.

Goal: Use a 99 Clone ECU in a 91 RT/TT.

What is needed:
-A 99 Clone ECU
-Adapter harness to connect your 91 vehicle side plugs to the 99 ECU interface
-Fan control - First gen radiator fans are controlled by temp switches at the bottom of the radiator, independent of the ECU. The 99 ECU controls the fans, so a harness to connect to the stock fans is needed
-Manifold Air Pressure (MAP), this sensor doesn't exist on first gen cars but the 99 ECU is not expecting a signal. No change required.
-Cam vs crank angle sensors. The 91 uses a cam angle sensor while a 99 uses a cam and crank angle sensor. No adjustment is needed as far as the ECU is concerned.

Please feel free to chime in. This isn't intended to be perfect on the first pass, and I will edit this post as more information flows into the thread.

[Greg E]

-Fan control - First gen radiator fans are controlled by temp switches at the bottom of the radiator, independent of the ECU. The 99 ECU controls the fans, so a harness to connect to the stock fans is needed

You can keep your 91 setup if you don't wish to convert to the ECU control.


-Manifold Air Pressure (MAP), this sensor doesn't exist on first gen cars but the 99 ECU is expecting a signal.

No it's not.


-Cam vs crank angle sensors. The 91 uses a cam angle sensor while a 99 uses a cam and crank angle sensor. I am sure there is some software adjustment that can be made to accomodate for the signal differences, if any is needed.

Nothing needs to be adjusted.

[Alex3000gt]

You can keep your 91 setup if you don't wish to convert to the ECU control.



No it's not.



Nothing needs to be adjusted.

Thanks for the info. I updated the original post. It looks like the ECU is just a drop in once you have a fan control harness and ECU adapter harness.

I am considering the 99 ECU as a replacement since my stock ECU finally kicked it due to leaking capacitors. I figured it may be a nice "future proof" for any future upgrades, and the new capacitors can't hurt either.

[Greg E]

I forgot to include the instructions for wiring up the 1G fans to be ECU controlled. (note: this setup is optional. Your fans will still work with the thermo-switch setup if you choose not to wire up ECU control)

http://www.cloneecu.com/wiring-guides/1g-fan-control

AND

http://chromedecu.org/?p=823

[ChargerX3]

Might want to make some minor timing map changes though once you get it. The latencies are slightly different.

[Alex3000gt]

What are the risks of not adjusting for the latencies? Not able to retard ignition timing under knock conditions quickly enough?

[Alex3000gt]

Getting closer to pulling the trigger on this. Need to buy the wife an anniversary gift first.

[Ange]

I forgot to include the instructions for wiring up the 1G fans to be ECU controlled. (note: this setup is optional. Your fans will still work with the thermo-switch setup if you choose not to wire up ECU control)

1G Fan Control | THE ORIGINAL VR4 Clone? ECU (http://www.cloneecu.com/wiring-guides/1g-fan-control)

AND

Chromed ECU | 91-93 Radiator Fan Control Conversion for Flash Ecu (http://chromedecu.org/?p=823)

damn never thought of that. need to get this. have fmic so probably a good idea for me.

[Chris@Rvengeperformance]

Lowering the fan temps makes a big difference in the cars temps. My car doesn't get over 190 hardly ever now

[aaronatstate]

What are the risks of not adjusting for the latencies? Not able to retard ignition timing under knock conditions quickly enough?

You will get knock more quickly. With the 1g setup on the flash ECU the timing is advanced up to 4 degrees in the upper RPMs.

The true timing the engine runs is: Timing called for by ECU + (RPM*.0005). This factors in the latencey differences for the different sensors.

I've been running a 99 Clone ECU in my 92 RT/TT for almost 3 years now with zero issues.

[Greg E]

Not sure what the point of having "true timing" serves. Its not like you can take your true timing numbers and plug them into your timing table.

[aaronatstate]

Not sure what the point of having "true timing" serves. Its not like you can take your true timing numbers and plug them into your timing table.

Because it tells you what the actual timing is based on the latency differences. It tells you how much timing you need to take out in the timing table to get the timing number you wanted.

Now, if we could just change how the ECU adjusts for the latency differences (not sure if its hardware or software), we wouldnt have to worry about it, but until then we need to know what the timing the engine is seeing.

[Greg E]

I disagree. Had this argument with Brett a couple times.

The number you see in the logger is the number the ECU is using. It may not be your "true timing" but its the value you use to tune with. The knock sensor tells you how much to add/take away from that. There is no magical number to give you the best power. You literally have to put a number in, log and advance/retard based on knock and power. The timing number is just a reference point. The true timing is nothing more than a complication that's confusing to new people (I deal with this question being asked a lot)

To argue that you "need to know the true timing" is like arguing that you "need to know the true airflow". If that statement was true, piggybacks wouldn't have worked for years so well on our cars.

You tune for power, not a number on the logger.

[akotten]

I disagree. Had this argument with Brett a couple times.

The number you see in the logger is the number the ECU is using. It may not be your "true timing" but its the value you use to tune with. The knock sensor tells you how much to add/take away from that. There is no magical number to give you the best power. You literally have to put a number in, log and advance/retard based on knock and power. The timing number is just a reference point. The true timing is nothing more than a complication that's confusing to new people (I deal with this question being asked a lot)

To argue that you "need to know the true timing" is like arguing that you "need to know the true airflow". If that statement was true, piggybacks wouldn't have worked for years so well on our cars.

You tune for power, not a number on the logger.

This is true, but having the correct values is nice. It makes more "sense" to those who understand flame travel speeds, propagation, etc. 4 degrees of timing can be a lot. It's personal preference really. Also makes it easier to compare tunes when everyone uses the same base otherwise its apples to oranges.

[CoreyB]

Thanks for posting this thread Alex, I plan on going flashable too.

[Alex3000gt]

Thanks for posting this thread Alex, I plan on going flashable too.

No problem Corey. At the time I felt a little silly posting it, but making threads is the only way to create searchable info on this forum.

[Alex3000gt]

I am a slacker. Just ordered a clone ECU, hope it gets here before the NG.

Alex

[Alex3000gt]

Plugged in the '99 ECU today and....

....

car runs like shit, popping exhaust with an idle of 500 RPM struggling to stay 'on'. Revved it up to 2500 RPM and was met with more popping in the exhaust and a check engine light.

Time to go buy an OBD2 scanner and pull the code because I'm certainly not driving the car to an auto parts store. Son of a.

[Alex3000gt]

Plugged in the '99 ECU today and....

....

car runs like shit, popping exhaust with an idle of 500 RPM struggling to stay 'on'. Revved it up to 2500 RPM and was met with more popping in the exhaust and a check engine light.

Time to go buy an OBD2 scanner and pull the code because I'm certainly not driving the car to an auto parts store. Son of a.

Confirmed that the front bank O2 sensor is bad. I learned that the 99 ECU, if it detects a bad O2 sensor, will go full rich and the car will run like crap.

Will be purchasing a new O2 sensor at 7:30AM when Autozone opens. Fingers crossed.

Alex

[Greg E]

Does the rear bank sensor cycle?

If the ECU detects a bad O2, it doesn't go full rich. It just doesn't apply the O2 fuel trim.

[Chris@Rvengeperformance]

Does the rear bank sensor cycle?

If the ECU detects a bad O2, it doesn't go full rich. It just doesn't apply the O2 fuel trim.

Everytime I've had a broken o2 wire it went +12.5 on the trim for that bank.

[Greg E]

Everytime I've had a broken o2 wire it went +12.5 on the trim for that bank.

Yes, it'll do that until the CEL is tripped. Once the sensor fault is detected, it'll ignore the trim.

[Alex3000gt]

We figured this out last week, but I did not update the thread yet. I am providing this update so that future people with a similar issue will have a search result, thereby increasing the knowledge content of this forum.

The adapter harness which connects my 1991-style vehicle wire harness to the 1999-style ECU had two wires switched. One wire was the ground for the MAF and TPS and the other wire was a 5V line.

As a result, upon plugging in the '99 ECU and starting the car - the boost gauge dropped off because it reads off the MAF signal. To further complicate issues, the ECU was not picking up a proper throttle position signal for the same reason. As you can imagine, the car ran poorly (unplug your MAF and TPS and go cruise around).

Brett fixed the harness immediately and I drove from the NG near St. Louis, MO back to Indianapolis, IN, picked up the car and brought it back to the NG. Car runs like stock, which is exactly what I was looking for. Brett took care of us, and Lisa even got a pink Clone ECU shirt. Thanks for fixing things Brett.

[Greg E]

My offer to give you a free setup tune still stands. :)

[Alex3000gt]

My offer to give you a free setup tune still stands. :)

Thanks Greg. We'll have to have a chat soon.

Alex

[DuctTapeProdigy]

I just installed the 99 clone ECU in my 91 VR4. I've cut the cranking IPW tables and plugged in the injector battery latency values and injector size fields for my injectors. The car starts, with some hesitation, and idles for a short period of time with or without any throttle input. I thought at first this may have been the fuel pump relay, so I changed it so the fuel pump as always on high speed mode, without noticing any changes in this behavior.

I've run a log and the "Timing Advance" stays at 5 degrees even after I have stopped cranking.

It also appears as if the tach is now reading load instead of RPM. If I stab the throttle, it will shoot up to 6k rpm, even tho the motor is struggling to turn over at 1.5k or so. Modulating the accelerator pedal results in the tach needle modulating all over the gauge, and the engine seems completely unresponsive.

My TPS and MAF seem to be reading as expected.

[Greg E]

Few ideas:

*Your adaptor harness is messed up. Something is telling the ECU to stay in SAS mode. Shoot Brett a message.

*Your CAS or plug at the CAS is messed up

*Your PTU or harness is messed up.

What's the car run like with the stock ECU?

[DuctTapeProdigy]

The car was running fine on the factory ECU. One of the stock injectors went bad (open circuit) and I replaced them all with aftermarket replacements (requiring the flashable ECU). The base idle timing was set to 7 degrees (Grounding out the beige circular plug behind the battery).

Do I need to adjust the timing of the CAS? My car does not have a crank angle sensor.

[99 vr4]

I just installed the 99 clone ECU in my 91 VR4. I've cut the cranking IPW tables and plugged in the injector battery latency values and injector size fields for my injectors. The car starts, with some hesitation, and idles for a short period of time with or without any throttle input. I thought at first this may have been the fuel pump relay, so I changed it so the fuel pump as always on high speed mode, without noticing any changes in this behavior.

I've run a log and the "Timing Advance" stays at 5 degrees even after I have stopped cranking.

It also appears as if the tach is now reading load instead of RPM. If I stab the throttle, it will shoot up to 6k rpm, even tho the motor is struggling to turn over at 1.5k or so. Modulating the accelerator pedal results in the tach needle modulating all over the gauge, and the engine seems completely unresponsive.

My TPS and MAF seem to be reading as expected.


Got your PM.

Just to confirm you have a 1991 California Emissions Car, correct?

Also I put Chrome v2.0.1 on there since you donated and used the coupon code. When you re-flashed, did you use the version on the ECU or did you load a "fresh" version from a download, or did you start with someone else’s "base tune"?

Did you have any issues flashing?

When you say you cut the cranking IPW tables, what do you mean exactly?

What kind of injectors did you install? I just want to make sure you put the correct injectors in.

The harness was tested on a "test jig". The chances of actually having a bad one are one in a thousand and Alex already got that one. But I can call you later to verify the major voltage lines.

I might tend to think you have something messed up with the PTU or the PTU wiring, since the tachometer is not driven by the ECU, but by the PTU directly. The ECU drives the PTU, which although highly unlikely, could have taken a dive between when I tested it here on the road and shipped it to you. I have not had that happen before, but I suppose anything is possible.

Brett

[DuctTapeProdigy]

Got your PM.

Just to confirm you have a 1991 California Emissions Car, correct?

Also I put Chrome v2.0.1 on there since you donated and used the coupon code. When you re-flashed, did you use the version on the ECU or did you load a "fresh" version from a download, or did you start with someone else’s "base tune"?

Did you have any issues flashing?

When you say you cut the cranking IPW tables, what do you mean exactly?

What kind of injectors did you install? I just want to make sure you put the correct injectors in.

The harness was tested on a "test jig". The chances of actually having a bad one are one in a thousand and Alex already got that one. But I can call you later to verify the major voltage lines.

I might tend to think you have something messed up with the PTU or the PTU wiring, since the tachometer is not driven by the ECU, but by the PTU directly. The ECU drives the PTU, which although highly unlikely, could have taken a dive between when I tested it here on the road and shipped it to you. I have not had that happen before, but I suppose anything is possible.

Brett

Yes, this is a 91 Turbo Cali spec with FIC 1050cc low-z injectors.
I flashed the ECU with the chrome 2.0.1 file that I modified for larger injectors (injector size=1071, changed the Injector Battery Voltage Latency Compensation table as well). I halved the values in the Cranking IPW table as a starting point.

I noticed my rom flashed much quicker than I was used to seeing when doing full ECU flashes such as the tephra mod on my eclipse. I know this is because the flash did not have to modify the entire ROM of the ecu, and only the bits I changed. Didn't have any issues flashing. I proceeded to play around with a few of the starting tables to get the car to start up within a crank or 2.

I have a copy of the factory vr4 rom. Would you recommend me trying to flash with the 99 stock VR4 rom with the injector tables modified?

I have a few spare known working PTU units, but I'm about 99% certain the one currently on the motor is working as well, as I did not have any problems with the tach running the factory ECU with factory injectors.

[DuctTapeProdigy]

I have copied a startup log over to a Google spreadsheet.
https://docs.google.com/spreadsheet/ccc?key=0AlKahrY6x0_2dGVwZ09FOFZQWFg4emJ5d0RzZDAtQ UE&usp=sharing

Green is where I was cranking. It looks like the car tries to get out of the 5degrees, and momentarilly hops up to 28 degrees, before the car stalls.
Note after 14 seconds of running, the ECU kills the injectors and the car dies, shortly after the 28 degrees of timing advance.

[99 vr4]

Greg,

It shows that the injector pulsewidth is stuck at 1.28 . . . kinda wierd.

I asked Chad to log "actual" timing instead of timing advance and post that along with the rom file for us to look at.

He says that nothing else has been done to the car, he has stock intercoolers and intake, but has 19T turbos and the 1050cc injectors.

Brett

[Greg E]

I have a copy of the factory vr4 rom. Would you recommend me trying to flash with the 99 stock VR4 rom with the injector tables modified?


Won't make any difference. Chrome is a stock ROM.


I asked Chad to log "actual" timing instead of timing advance and post that along with the rom file for us to look at.


Again, won't make a lick of difference. "actual" timing (you called it "true" timing) is a useless number which is calculated from "timing advance" anyway which is the number the ECU is calling for which is the number we need to know.

That moment when the car dies when the ECU goes into closed loop or at least tries to. That's why the car dies. 1.23 IPW is the minimum value the code will run the injectors at. You need to lower the Injector Min Pulse Width value table (it's in the fuel section) to be a lower value. I'm guessing closed loop is trying to pull fuel and it can't because the only thing less than 1.28mS is 0 according to this limit value. Hence the engine dies.

Can you post your timing map? 5 degrees at only 15 load is about 1/3 of stock. The stock timing map calls for 15 degrees in that area. The only time it'll be fixed at 5 is if you're in SAS mode.

Also, the tach signal comes directly from the PTU. Nothing in between besides some connectors and a wire. Better go back and examine those.

[DuctTapeProdigy]

I did lower the min injector pulse down to 0.5 mSec, and examined the same behavior. I was able to get the ipw down to 1.028 mSec if I revved the motor to about 3300rpm in idle. The timing never went above the 5 degrees tho.

I am using the default timing map that came with chrome.

EDIT: going over my logs, the IPW went down to 1.024 mSec, not the 1.028 like I mentioned above.

[Greg E]

I did lower the min injector pulse down to 0.5 mSec, and examined the same behavior. I was able to get the ipw down to 1.028 mSec if I revved the motor to about 3300rpm in idle. The timing never went above the 5 degrees tho.

I am using the default timing map that came with chrome.

The ECU must be retarding the timing in an attempt to lower the RPMs.

Something isn't right and my guess its outside the ECU.

[DuctTapeProdigy]

So, just for kicks, I installed the factory ECU while keeping the 1050cc injectors. Car started up and idled very well (Very rich, but still better than the clone ECU). I tried modulating the throttle, and the tach did not jump around at all like it does with the clone ECU. I've traced the wires going to the PTU and the beige idle adjust connector, and none appear to have any shorts or open circuits. The car did not kill itself after idling for the 15 seconds on the stock ECU.

I can't be the only one who has run these injectors on 91 octane... What's going on with my car?

Should I start cutting into the plug and play harness?

After the car kills the injectors on the CloneECU, I am unable to start the car again... the injectors do not fire, even when cranking. I have to turn the ignition to off, and then I can start the car again. The ISC steps go back into the cranking position, but the ECU does not fire the injectors.

The car does not have any aftermarket alarm system.

[DuctTapeProdigy]

Posted up another log... This one was able to see the RPMs doing weird things. (Highlighted in red). Notice the cranking (green) and the car not firing the injectors at all.
https://docs.google.com/spreadsheet/ccc?key=0AlKahrY6x0_2dGJWSVlITnM2b0NJQVpwNGFHVDI5T lE&usp=sharing

[Greg E]

Email me the file currently flashed to your ECU. If that's good then there is something whack with either your adaptor harness or the ECU itself then.

Nonstopmix@gmail.com

[DuctTapeProdigy]

Sent.

[99 vr4]

Chad,

I received the ECU and harness Saturday. I tested the harness, performed a visual inspection of the ECU, then after changing the start IPW, injector sizes, and MAF tables of the ROM you had loaded in the ECU, the ECU started and ran my VR4 just fine.

I can find nothing wrong with the ECU or Harness that would cause the problems you are having.

I spent some time on the phone with Greg, and at this point I think that the issue is the tune, specifically the injectors... Size, latencies, etc.

Have you verified that the injector size and latencies that you have loaded are specifically for the VR4 and not the vales used by the EVO guys? There have been some discrepancies in the past related to injectors that work fine with one value in the EVO but require a different value for the VR4.

Brett

[Greg E]

Correct. You can't use the values posted in that large Thread posted on EVOm. I used a different (more accurate) scaling to translate the ROM values to match the injector size.

For injector scaling you simply enter the size of your fuel injectors. For latency values, use the fuel injector clinic values I linked in the chrome thread. Adjust the voltage axis to match theirs.

Start with that, then there will be a few other tweaks to some tables which you'll need to do. Like scaling back the coolant temp enrichment and then some adjusting to the MAF comp (VE) tables.


I have no idea what is causing your odd RPM numbers but in your doc you just posted I see the injectors opening when airflow is detected as it should.

[Alex3000gt]

So, just for kicks, I installed the factory ECU while keeping the 1050cc injectors. Car started up and idled very well (Very rich, but still better than the clone ECU). I tried modulating the throttle, and the tach did not jump around at all like it does with the clone ECU. I've traced the wires going to the PTU and the beige idle adjust connector, and none appear to have any shorts or open circuits. The car did not kill itself after idling for the 15 seconds on the stock ECU.

I can't be the only one who has run these injectors on 91 octane... What's going on with my car?

Should I start cutting into the plug and play harness?

After the car kills the injectors on the CloneECU, I am unable to start the car again... the injectors do not fire, even when cranking. I have to turn the ignition to off, and then I can start the car again. The ISC steps go back into the cranking position, but the ECU does not fire the injectors.

The car does not have any aftermarket alarm system.

The fact that the tachometer goes wild with the Clone ECU and not with the Stock ECU is a cause and effect. It would seem that the tachometer signal has been crossed with something else, possibly the TPS signal. If the ECU was receiving some unknown signal in place of RPM this would be devastating to the control system's ability to operate.

I would strongly recommend checking and double checking the RPM signal wire.

To test this theory, let's take a look at the log of engine RPM versus throttle input over time.

[DuctTapeProdigy]

The fact that the tachometer goes wild with the Clone ECU and not with the Stock ECU is a cause and effect. It would seem that the tachometer signal has been crossed with something else, possibly the TPS signal. If the ECU was receiving some unknown signal in place of RPM this would be devastating to the control system's ability to operate.

I would strongly recommend checking and double checking the RPM signal wire.

To test this theory, let's take a look at the log of engine RPM versus throttle input over time.

I unplugged the Throttle position sensor (and idle switch) and the car still had erratic RPM issues with the '99 ecu. I decided to trace out a few pins on the wiring harness, and I think I found the problem. On the adapter harness, this is what I've found so far...

Using Stealth 316 - ECM pin assignments (http://www.stealth316.com/2-ecu94.htm) for pinouts

My 91's AirFlow pin is pin 70, this is going into the '99 ecu as pin 43. Pin 43 on '99 ecus should be the input for Crankshaft Position Sensor (Not Airflow!!!)
Pin 68 (Top Dead Sensor) is going into '99 pin 50 (Camshaft position sensor)
pin 69 (Crank Angle Sensor) is going to '99 pin 61 (Airflow)

The Harness appears to have wires going to the wrong places.

For the 1g VR4s,
Pin 69 should go to pin 43 on the '99 ecu (Crank position)
Pin 68 should go to pin 50 on the '99 ecu (Cam Angle Position)
Pin 70 should go to pin 61 on the '99 ecu (Airflow)

[Alex3000gt]

Chad,

I received the ECU and harness Saturday. I tested the harness, performed a visual inspection of the ECU, then after changing the start IPW, injector sizes, and MAF tables of the ROM you had loaded in the ECU, the ECU started and ran my VR4 just fine.

I can find nothing wrong with the ECU or Harness that would cause the problems you are having.

I spent some time on the phone with Greg, and at this point I think that the issue is the tune, specifically the injectors... Size, latencies, etc.

Have you verified that the injector size and latencies that you have loaded are specifically for the VR4 and not the vales used by the EVO guys? There have been some discrepancies in the past related to injectors that work fine with one value in the EVO but require a different value for the VR4.

Brett


I unplugged the Throttle position sensor (and idle switch) and the car still had erratic RPM issues with the '99 ecu. I decided to trace out a few pins on the wiring harness, and I think I found the problem. On the adapter harness, this is what I've found so far...

Using Stealth 316 - ECM pin assignments (http://www.stealth316.com/2-ecu94.htm) for pinouts

My 91's AirFlow pin is pin 70, this is going into the '99 ecu as pin 43. Pin 43 on '99 ecus should be the input for Crankshaft Position Sensor (Not Airflow!!!)
Pin 68 (Top Dead Sensor) is going into '99 pin 50 (Camshaft position sensor)
pin 69 (Crank Angle Sensor) is going to '99 pin 61 (Airflow)

The Harness appears to have wires going to the wrong places.

For the 1g VR4s,
Pin 68 should go to pin 43 on the '99 ecu (Crank position)
Pin 69 should go to pin 50 on the '99 ecu (Cam Angle Position)
Pin 70 should go to pin 61 on the '99 ecu (Airflow)

Well that is annoying. I had a similar harness SNAFU on my car.

I would reach out to Brett and let him know what you found.

These harness mixups are not acceptable.

[Greg E]

These harness mixups are not acceptable.

Agreed.

[2fnloud]

But who's harness was it?

[Alex3000gt]

I just installed the 99 clone ECU in my 91 VR4. I've cut the cranking IPW tables and plugged in the injector battery latency values and injector size fields for my injectors. The car starts, with some hesitation, and idles for a short period of time with or without any throttle input. I thought at first this may have been the fuel pump relay, so I changed it so the fuel pump as always on high speed mode, without noticing any changes in this behavior.

I've run a log and the "Timing Advance" stays at 5 degrees even after I have stopped cranking.

It also appears as if the tach is now reading load instead of RPM. If I stab the throttle, it will shoot up to 6k rpm, even tho the motor is struggling to turn over at 1.5k or so. Modulating the accelerator pedal results in the tach needle modulating all over the gauge, and the engine seems completely unresponsive.

My TPS and MAF seem to be reading as expected.


But who's harness was it?

I'll let DuctTapeProdigy make the final call, but based on the quote above it appears to have been another Clone ECU (like mine) which would mean Brett. (99 VR4)

[DuctTapeProdigy]

Yes, I got this whole setup from Brett. I am still not able to get the car to start, even after swapping those 3 connections.

Car still starts OK (a bit rough and super rich as expected due to 1050cc injectors) on the factory ECU. Can't get it to start using even the factory 99 ROM on the 99 ecu.

EDIT* It looks like I had swapped the Cam/crank pins when I found the air flow pin was going to the wrong place. I changed my post above to reflect the proper pins after talking to Brett.

Car starts up very quickly now that it can see the crank/cam signals correctly.

Now I can finally start to tune the car.

[Greg E]

Yes, I got this whole setup from Brett. Who else makes an adapter harnesses? I am still not able to get the car to start, even after swapping those 3 connections. I am extremely frustrated with this entire "Plug and Play" experience.

Car still starts OK (a bit rough and super rich as expected due to 1050cc injectors) on the factory ECU. Can't get it to start using even the factory 99 ROM on the 99 ecu.

Chrome is a factory ROM. If it doesn't run with chrome it won't run with a stock ROM....

Have you spoken to Brett about the harness issues?

[99 vr4]

I unplugged the Throttle position sensor (and idle switch) and the car still had erratic RPM issues with the '99 ecu. I decided to trace out a few pins on the wiring harness, and I think I found the problem. On the adapter harness, this is what I've found so far...

Using Stealth 316 - ECM pin assignments (http://www.stealth316.com/2-ecu94.htm) for pinouts

My 91's AirFlow pin is pin 70, this is going into the '99 ecu as pin 43. Pin 43 on '99 ecus should be the input for Crankshaft Position Sensor (Not Airflow!!!)
Pin 68 (Top Dead Sensor) is going into '99 pin 50 (Camshaft position sensor)
pin 69 (Crank Angle Sensor) is going to '99 pin 61 (Airflow)

The Harness appears to have wires going to the wrong places.

For the 1g VR4s,
Pin 68 should go to pin 43 on the '99 ecu (Crank position)
Pin 69 should go to pin 50 on the '99 ecu (Cam Angle Position)
Pin 70 should go to pin 61 on the '99 ecu (Airflow)

HOLY CRAP!!!

Chad texted me today with this issue. We spent a few minutes on the phone to verify some pint outs.

What makes this frustrating even as a builder, I use a test JIG that should prevent this. This would make TWO harnesses during the lifespan of this project that the test JIG did not catch. Time to re-engineer the test JIG! Although this represents a <2% error rate, I also agree that this is unacceptable. I know that I would be pissed as a customer.

To clairfy:
Pin 68 (Cam Signal for TDC) should go to Pin 50 on the 99 ECU
Pin 69 (Crank Angle) should go to Pin 43 on the 99 ECU
Pin 70 (MAF) should go to Pin 61 on the 99 ECU

It appears that the Crank angle and MAF signals were crossed!

Obvously if the MAF sent a signal to the crank angle, this would cause all of the issues that Chad was having. What makes this worse, is that the test JIG did not catch this. The harness passed testing. Although not impossible, a crossed wire should not pass testing, and the test JIG has caught errors in the past.

Chad, I have sent you money via PayPal because of the troubles you have had. Again I am sorry that this happened.

Brett