I have a 91' T/A GTA w/LB9. It has a 700R4. One morning i was leaving and the car started acting real funny losing power and everything and it gave me a SES light. So i took it back. Well i just got it home about 4 days ago and i cant get it to give me a code with a code key or paper clip. I had a friend hook a scanner on it and it said it couldnt make a connection. So somethings wrong between my ALDL and my ECM. But what. It idles VERY rough like it has a monster cam in it and its at about 250 RPM. Yes "250" rpm. It also smokes black smoke. When i hit the gas it pops and backfires through the intake. When it gets above @3000rpm it acts right. I pulled the 2 vaccum lines off the EGR solenoid and it ran fine for 2 days even when i put them back on. Now its doing the same thing again. And the vaccum line trick isnt working(even if that was it). I have checked the sensors and the grounds and still cant get nothing. It even does it in OPEN LOOP mode. Please help. Anything to give me a head start will help. Thanks

 

Maybe your O2 sensor is dead?

 

its brand new. But even if it was it wouldnt run like that in the open loop mode.

 

that sounds a lot like how my 91 L03 ran when the Vacuum line the the MAP was ruptured...

 

checked it....its fine too..

 

I'd look to your EGR Valve. If pulling the vac lines off of it effected it then that's where I'd start. Does anyone remember the effects caused by an EGR with Excessive flow?

David

 

Would a bad or stuck EGR valve have any effect in the open loop mode?

 

if it was stuck open, it would seriously screw up low-rpm engine functionality, while not affecting higher rpm's much, if at all...

 

LB9 have dual cats? If so it would be doubtful, but it sound like the symptoms my fathers Audi had when the cat was cloged. Any loss in power means that there is flow problems, either air, fuel or exhuast. Other than the egr I dunno what could go wrong with the airflow, and fuel and you would have detonation troubles or a bad O2, so I say exhaust.

 

i dont have a cat.

 

also forgot to tell. At the exact moment that it messed up my speedo quit working. Any relation?

 

If it was electical, ie computer, it wouldnt run at all.

 

Change your PCV value or at least check to see whether or not it is seated properly.

 

it was the ecm gone bad..

 

That actually happened to me twice with my 91 RS

 

the one in there already was only about 1 year old. Was there some kind of recall or anything that maybe causing the 91' ecms to go bad?

 

none that I know of