I have a 91' T/A GTA w/LB9 and a 700r4. Its idleing very rough to the point it wants to die. Above 2800rpm or so it gets it power back. While it is running it has a VERY rich smell and wants to smoke black smoke. I used a code key and couldnt get any codes so a friend brought a scanner over and it sayed it wasnt connected. I checked 3 grounds under the hood and adjusted them for a good connection and that didnt work. The grounds were 1) Firewall to Right head 2)black wire grounded to front right fender 3)black wire grounded to front left fender. I also checked the voltage on my TPS-MAPS-new O2s-IAC-etc. They all read fine. BUT....my cars been down for about 2 weeks. A week ago i pulled 2 vaccum lines off the the EGR solenoid and put them back on and it ran fine for about 2 days. Now its doing the same thing again. Hence though when i pull the vaccum line off the brake booster i get a regular idle but if i hit the gas it hessitates and "backfires" through the intake. What could this be and why isnt my ALDL working? And it does this in "open loop" mode. Will a stuck or bad EGR does this in open loop mode and when i pulled the vaccum lines off the EGR solenoid maybe that unstuck it? Please help

 

Were you ever able to pull codes. If so sounds like you have a bad ecm. I had the same problem in my '86

 

nope... I couldnt get any codes with a code key or a scanner. If the ecm is bad will it still crank and run half a$$ atleast? Does the ECM just GO or does it cause problems and run right sometimes before it goes out?

 

When my ECM went bad I couldn't get any codes. The car didn't want to idle and would miss really bad. It would blow black smoke everywhere and just ran like crap. I would also have problems keeping it running at idle and it would crank for a while before it started

 

Thats just what mine is doing. Thanks alot man!

 

Same problems, new ECM on order and will Post results when installed. Been going around with the idle problem for six months now and the ECM is the LAST Resort.