1991 tpi 6 spd.
car was running well. i switched out the plenum and runners for slp runners. I dropped in a used msd distributor, but went bqack to the original due to a possible bad pick up coil. I reset timing as your supposed to and idle is at 1k rpm. i noticed the fan slowly turning which they didnt before. engine has a slight vibration. i dont hear or feel any vacumm leaks. i went to check for codes and the SES is not coming on at ignition or when A and B are connected.
I didnt run the engine loger than about ten minutes at a time. wondering if i need it to run longer for the computer to reset. or is it something else
thanks

 

SES should work at key-on. That is the bulb check. If that doesn't work and the bulb/circuit is good then the ECM is bad.

GD

 

i doubt the bulb just went out but possible. it was working the day before. but i will check it. with a bad ecm the car will start and run?

 

Yes it could. There is a resistor network built into the memcal that can run the engine in limp mode even if the ROM is corrupt, etc.

Lack of SES light and inability to pull codes is very similar to my original 7165 ECM that had a cracked circuit board. Sometimes it would run - sometimes it wouldn't. And it's behavior would change if you tapped on it with a screwdriver handle.

But it's probably related to the recent work and the bulb or the circuit may to be blame. Check those first. If you ground the pin on the ECM the bulb should lite. Also check all the grounds for the ECM. It can't ground the bulb if it doesn't have a ground reference.

1k is wrong for idle speed. At least with a stock ROM anyway. 650 is about where the stock ROM will idle.

GD