I have a 1992 Buick Lesabre with 135,000 miles. It has the bulletproof 3.8 3800 engine. The engine runs well when first started. It continues to run well for about 30 minutes. Then it will begin to cut out under acceleration. It will continue to worsen the longer you drive it. You have about 1 inch of pedal travel where it runs okay. You can floor the gas, and it will cut up so much it's almost as if it has died, but doesn't. It doesn't smoke and only backfires occasionally when under hard acceleration. It comes right back to idle with no stumbling or anything else.
It idles fine incidentally all the time and will not die even when it runs like this. It's just under acceleration when it's been driven for some time.
This is what gets me: It will continue this behavior until you cut the engine off and immediately restart it, at which point then it will run fine for a couple of minutes and then begin cutting out again. Interestingly enough, you can let it idle for more than 10 minutes from a good start even when the engine is warm, and it will not do this. Take off down the road and it starts again. The longer you drive it, the shorter the periods it runs okay decrease.
The car will run well again once you let it sit for a while (20-30 minutes). I have already replaced the coil packs btw. I was replacing some stuff on the car in the dash, and I had the battery disconnected for two weeks in the garage. No SES light before or now.
Fuel pump overheating and trying to shut down?
Bad plug wires?
Burnt wire on engine harness? Grounding somewhere?
Bad O2 sensor? (Should have SES light?)
Any help is greatly appreciated. This is normally a great running car, and I really need it to work in it. It has that great GM paint.I think you know what I mean.
Friday, March 23rd, 2007 AT 3:56 PM