94 Firebird Lt1

**kenimpzoom2** · 03-12-2022

BLM.JPGFirst off i am new to EFI, but been working on cars for 40+ years.

My 94 Firebird with LT1 is stock. Right now it has a major stumble when warm, no stumble when cold. So it seems to be worse in closed loop. Both O2 sensors are new Bosch units.

Runs great at WOT. Idle is a little bit rough, but not bad.

I filed the log with EE Hack.

1st question is, why does the BLM on right bank say, BLM learn, and the other is pulling from the BLM cell 16?

Thanks, Ken

**WASyL** · 03-12-2022

as for cell 16 and BLM learn you don't read it as left and right, it is just layout of program, it is just cell 16 and BLM are learning for both banks. this printscreen shows that right bank is very lean so PCM adds lots of fuel, and left bak is also lean but adds less fuel. this might be caused by leaking injector or bad o2 sensors. i had lots of problems with cars when using other sensors then AC Delco ones. this condition will cause poor idle, poor mileage and still engine will work fine on WOT. start with switching o2 sensors from side to side and see if BLM reading will switch, if yes o2 sensors are bad. then verify for leaking injectors. also poor CR, damaged CCP or PCV system my cause this issue.

best regards

**kur4o** · 03-12-2022

Both O2 sensors are new Bosch units.

If no mechanical issue, that is likely your problem. One fellow member here have used similar sensor which produce very low switching signal and they landed in the trash. Get a good US made ac delcos afs-75 I think was the number.

Some complete log will help also. You may have vacuum leak or some other issue.

**kenimpzoom2** · 03-15-2022

Thanks all for the tips. I switched the O2 sensors around and saw the readings were the same so that indicates the O2 sensors were good. I am 99% sure its leaking fuel injectors. Sometimes it runs great, othertimes I get the hesitation. These injectors were cheapo rebuild ebay specials, knew it was a crap shoot if they would work. I just sold the car back to original owner, so I told him the problem and let him know it needs new injectors.

Thanks everyone. Ken