Hi, I'm trying to troubleshoot my starting problems here.

I have a 90 TSI which has been converted to a 91-94 ECU, by changing power transistor, coil to make the tach work fine.

I had so many problems with all the ECU I have, that I can no longer trust the ECU, but the problem could be somewhere else.

Up to this date, I have a running AUTO Turbo ECU with a GM-MAF and MAFT, with 450cc injectors. The car seems to start fine, and when it's cold, the injector pulse time will bump up to 30-40ms to make it start. After, when I'm running, it doesn't run smooth, it's all rough, you can feel it jerk a little bit.

Then, I bought a 93 Turbo 5-speed ECU. Took about 5 minute of cranking here and there to make it start. The injector pulse time won't go any higher than 8-9ms, is this normal? But after it starts doh, the car will run really smooth, after I change the setting properly into the MAF-T.

I'm trying to understand how the fuel system works here. When the car is cold, should the ECU feed more fuel to make it start, by increasing injector pulse time, or there is no relation at all?

Someone told me to drive my car for at least an hour, to give the ECU some time to update itself, that's what I did yesterday. After 4 hours sitting, I went to try restarting the car, and it start fine. Then, this morning, same thing, it start really good. But, at the end of the day after work, it wouldn't start again, took another 5 minutes before it could start.

Could someone log their first start in the morning, with the injector pulse time, and send me a copy of their file at jonathanarseneau@hotmail.com?

You'll be in open loop during warm-up, and the ECU should dump extra fuel.
What does the ECU's coolant temp sensor say on a cold start when you're having problems?

If the IPW is low, then have a look also at the Airflow HZ # - if it is also low then there could be a problem with your translator setting, its wiring or the GM MAF itself.

I'm not sure how the MAF-T works with an auto ECU...
The auto ECU is mapped for 390cc injectors, but you're running 450s. With the MAF-T set to 450cc I would expect you to run rich. Maybe setting the MAF-T to 510 will help.

Well, the coolant temp sensor is fine, it gives me pretty much the same temperature than ambiant, and as the car warms up, it will go up, and reach 91-95 degrees celcius.

All others sensors seems fine also, I get air flow while cranking, I get around 200 RPM while cranking, 02 sensor works good. All the sensors are good, because once it has start, the car works fine, and will restart easy if it's hot. After it's sitting for a while, then it will only crank, and not start.

Could the 93 AWD ECU be reading the Battery Voltage, and if the battery is too low, it will not send any sparks? Cause when you crank, the voltage drops to 10.5 Volts.

Or the only thing, is I might have received a bad ECU, even if the seller pretend to be working good in his car. Well, the ECU works good, only after you get the car started.

The ECU does evaluate battery voltage, but I think it's more for fine-tuning.
If you have enough to crank, you should probably have enough to fire.
Unless there is a problem with the ECU - then you could expect any kind of electrical funnybusienss.
Of course, it can't hurt to try a known good battery (with clean connections), if only to eliminate that...

Why not try the auto ECU again with adjustment to the MAF-T setting?
If that works, then the 5spd ECU is probably the real problem.

Well, I did run my car all year around with the AUTO ECU, and I did tune it with the MAF-T, and I get the low, mid and high trim around 100%, but even there, it is not as smooth as the 5-speed ECU(when it's running of course). The fuel curve could be different in the AUTO ECU, because the engine load is probably not the same because of the trans.

To make the story short, I have 4 ECU with me (2 x AUTO and 2 x 5-speed).

-1st AUTO, starts good, but seems to not run as smooth as a 5-speed.

-2nd AUTO, have the same problem as my 93 AWD 5-Speed ECU, it takes a lot of cranking to start.

-1st 5-speed 93 AWD, well, runs smooth when it starts, but take a lot of cranking.

-2nd 5-speed 92 AWD, well, starts good, runs good, but after 5000RPM, I get fuel cuts, seems that the injector pulse time is too long because of erratic air flow reading, but the air flow meter is good (does that with GM-MAF and also with 1G MAF). I can see other sensors, like cool temp, battery voltage, oscillating and bouncing up and down.

I also have 2 others ECU that are fryed, just no luck with ECU here...

Since there is 2 ECU that does the same thing, hard time so start, I'm assuming that those 2 ECU are good, but I might have a problem somewhere else, either injectors, FPR, coil, I don't know.

It does sound like an ECU problem, but because you have so many to test with I think first you should try another battery and clean all the connections.
I'd try using the '93 AWD ECU with new caps installed it.

Oups, forget to tell you, that I have replaced my battery last week with a new one, my old battery couldn't hold charge, so it was under warranty, so my battery is brand new.

I've check back in my email, and I don't think the caps has been changed, but they look brand new, not even a leak from it.

People say that all 91-94 ECU are compatible, but when I check for all the fuel system components, there is one thing that is not similar. The 92 Cam Angle Sensor is not the same as the 93, could this be a problem? That could be why I have a problem to start, might not have sparks. If my memory is good, sparks come with the Cam angle sensor, or is it only fuel injector pulse that comes with cam angle sensor?

I did change the O-Ring at my cam angle sensor a few months ago, is it possible that I've put back my sensor 180 degree OFF, how would I know?

Yep it could be the CAS. Maybe it is giving an intermittant signal. Oil or water inside can damage them.

You could try turning the CAS dowel 180deg.
I think the groove in the dowel should face the front of the car when the #1 piston is @ TDC.