Cold start rough idle
Thread Starter
Advanced<br><img src="/forums/images/ranks/100-500.gif" border="0">
Joined: Apr 2019
Posts: 87
Likes: 29
From: Livermore, CA
2023 Corvette of the Year Finalist - Unmodified
2022 C4 of the Year Winner - Unmodified
Cold start rough idle
I have an 89 convertible. A stock L98 engine. On cold starts it idles very rough for about 10 seconds. After that it runs great. Warm starts are fine.
Any suggestions? Thanks for the help.
Shafe
Any suggestions? Thanks for the help.
Shafe
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
Have you tried taking the throttle body off, IAC off, IAC housing off and the top plate off? Clean off everything. Reassemble and set it by NOT using the FSM method. Get a scanner and set it using IAC counts.
Safety Car
Joined: Aug 2013
Posts: 4,430
Likes: 609
From: Minneapolis Mn
At one time, mine would run fine for about 3 blocks from a cold start then ran like crap, did it randomly. Turned out to be the IAC valve was the problem. Replaced and the problem went away.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
Just for the hell of it, when the engine is cold, scan the ECM and check for coolant temp and ambient air. Should be about the same. Hit it with an IR thermometer. See the difference and note it. Go for a drive. See what the ECM says the temps are and what the IR Thermometer says. See if the sensors are bad or good.
Thread Starter
Advanced<br><img src="/forums/images/ranks/100-500.gif" border="0">
Joined: Apr 2019
Posts: 87
Likes: 29
From: Livermore, CA
2023 Corvette of the Year Finalist - Unmodified
2022 C4 of the Year Winner - Unmodified
Thanks.
Thank you for ideas for solving my problem. I will let everyone know when I get it done.
Shafe
Shafe
