Rough Idle !
Thread Starter
Instructor
Joined: Jan 2002
Posts: 245
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From: Newport News VA
Rough Idle !
My LT 1 idles eraticly. When running the idle varies between 600-900rpm, then settles down around 600. This continues and is more pronounced with the ac on. I recently had the dealership 'fix' the problem, and their answer was to preform a tune up which did nothing. Tune up consisted of new air filter (ALmost throwing away my K&N for crappy GM) and PVC valve, plugs & wires. Car has 85,000 miles on it. One thought is the idle air control valve however, I think it may be computer related. Any thoughts ?? I want my $600 back !! :confused:
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: Rough Idle ! (9T4YY1)
I would never pay a dealership $600 for a tune up. Their techs are simply parts changers, and can't usually diagnose anything beyond what they can lookup in the book or on the GM online tech network.
Dirty or failing IAC was my 1st thought as well, since AC on aggravates it. Ignition system problems (coil, ICM) usually tend to exhibit themselves at mid to high rpms, so I would say nay to that for now. Here's my other guesses, in order of suspicion:
1. EGR valve full of build-up and not shutting all the way
2. Vacuum leak somewhere
3. Dirty MAF sensor (oil from the K&N can get on the tiny diodes and cause them to get grime build-up accumulating).
4. Fuel delivery problem, possibly an injector or two getting flakey on you
Dirty or failing IAC was my 1st thought as well, since AC on aggravates it. Ignition system problems (coil, ICM) usually tend to exhibit themselves at mid to high rpms, so I would say nay to that for now. Here's my other guesses, in order of suspicion:
1. EGR valve full of build-up and not shutting all the way
2. Vacuum leak somewhere
3. Dirty MAF sensor (oil from the K&N can get on the tiny diodes and cause them to get grime build-up accumulating).
4. Fuel delivery problem, possibly an injector or two getting flakey on you
