Im having trouble with my 99 coupe (daily driver) missing when I first start it of a morning. It will run rough and the exhaust smells like it is very rich. I had no problems with it at all until I took it in to the dealer. Sometimes it would not start when I turned the key and I would have to wait a few minutes and try it again and repeat until it would start, but the week I decided to put it the shop it was a constant problem. But it ran great when it would start. I was having the column lock recall done and they were going to replace the oil pressure sensor because it went out. Then the headache began. They found that my AC Delco battery had leaked and damaged some of the wires below the battery. They had to replace the BCM (so they said) the battery tray, the oil pressure sensor and they replaced the damaged wires. But now it misses until I drive about 15-20 minutes usually (found out on my way back to dealer) then it drives fine. They cant find a problem when I get to the shop but they see the trouble codes due to the misfire. They did a complete fuel flow test and said it was perfect. The key thing was still happening also but it seemed to go away when I replaced the battery with an Optima yellow top which makes me think the relay for the theft det. system might be getting weak. Is it a grounding problem? I dont really see how it could be the computer since it runs fine after 15-20 minutes. The service engine light even goes off if I drive it long enough. I thought it was maybe because of condensation on the car overnight but it does fine in the heaviest rain. Any ideas? Please my baby needs doctorin' and I have already spent $2100 at the dealer, any ideas would be appreciated.

 

Wow, you have been having a bad week. The Key and the Battery could well be related, I have seen others post about that type of symptom when their battery was low.

The cause of the misfiring, however, is beyond me. I'll defer to the more technically capable in the group.

Hang in there - it'll be better again..

 

I believe the BCM is in the passenger footwell. The PCM is what could be damaged by the leaking battery. If the dealer told you they replaced the BCM, I would question if they really did and why. Just my .02.

 

Sorry, It was the PCM that the dealer replaced. Too many acronyms for my short memory. The thing is it ran great until the swap and now it always starts rough. Man I would rather have a mechanical problem than an electrical one anyday. Well almost anyway.

 

Welcome to the Forum ...and good luck with the fix!

 

I'am going along with Jim on this one!

 

are you the original owner? If so have you had any mods done to the car that require a LS1 edit. If so then when they replaced your pcm you lost your tune. Another thought is make sure that all connections to the CAI are tight and snug. Make sure all hoses to the TB are secured and snug. If the car runs rough during initial start-up and then fine 15 minutes later its because your pcm has relearned the a/f ratio to compensate for either too much air or too much fuel. Sounds me like it shouldnt be too difficult for the dealership to nail down. I would suggest that after you check all of the above that you take it another dealer. Good Luck

 

$2100 and still no remedy? OMG!

My first guess was a leaky fuel injector that would flood your engine, hence the misfire and the rich fuel smell.

I would take it to another place but not before taking half or most of my money back since they have not fixed anything.