engine idle problem
Thread Starter
Racer
Joined: Oct 2001
Posts: 279
Likes: 1
From: Stonewall N.C.
engine idle problem
When I crank up my '86 L-98 it start's out with a very high idle, real high, then it backs down to 800-600 rpm and stays there, then I'll drive for awhile and come to a stop while waiting for the t. light to turn and she's back idling high again, ready to fly, can anyone tell me what's wrong? thanks again!
Pro
Joined: Jan 2002
Posts: 596
Likes: 0
Re: engine idle problem (vettedreams)
The motor always starts with a high idle..usually until it warms up to about 150 or so. Other then that..a million possibilites could be effecting your idle. Try finding someone with a OBD 1 scanner and look for a bad MAF, IAC, TPS, Knock, and other codes. But as for other possibilities, check for vacuum leaks, esp. the hard line hose at the pass. side rear of the plenum, and try taking out the IAC and give it a good cleaning. Hope you can find that problem. Good luck
Team Owner
Joined: Sep 2001
Posts: 62,157
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: engine idle problem (vettedreams)
thats normal at start up, and normal idle is about 6-700rpm in mine. Now if its surging and jumping up to 8-900 then it sounds like you need to clean or replace the IAC
Thread Starter
Racer
Joined: Oct 2001
Posts: 279
Likes: 1
From: Stonewall N.C.
Re: engine idle problem (neekos)
I do know that on my '86 the IAC is plugged in under the TPS, under the throttle body just don"t know anything about the actual cleaning of the valve.
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