After a head gasket replacement and fuel injector replacement I havent been able to get my car running right. It seems to be running rich and the it intermittenly backfires in the intake runners. I have checked and double checked the timing, EST, distributor placement, vacuum leaks, compression, and fuel pressure. Yet the problem continues. I do recall checking for codes at one time and accedently starting the car with the diagnostic terminals grounded. I quickly realized it and shut if off but is there a possibility that I could have effected the ECM? Would it be just the ECM or the EProm also? 89 Firebird 350 TPI. Thanks in advance

 

I've heard that starting the car with A & B shorted can damage the ECM, never witnessed it though. With the head(s) being off double check the grounds that get tied to the back of the cylinder head(s). Check the wiring for possible damage.

Are the replacement injectors the same flow as the originals?

RBob.

 

I've checked and double checked all the grounds connected tot the block. Yes the injectors are the same exact ones as the originals. I did some more testing today and I got it running really good but the catch is the timing is advanced 12 degree's. What would cause this? It runs great here with no pinging or detonation of any kind. Its also no longer overheating. Anyone got any explanations? Thanks in advance.

 

Open the EST connector when setting the timing?

RBob.

 

Thats the scarry part. I did.

 

I agree, what does the timing do once the EST is reconnected and the engine cycled off-wait 10 secs-back on? The timing should then be around 22-24° BTDC. Wonder if the balancer slipped sometime between the last timing set and the headgasket change.

Retarded timing would also cause the overheating problem.

RBob.

 

I will check today but the harmonic balancer was replaced last year. I hope thats the problem.