1989 C4 Hi Idle
Thread Starter
Heel & Toe
Joined: Aug 2018
Posts: 17
Likes: 0
1989 C4 Hi Idle
I fire the car up and it idles about 1100 rpm as it warms up the ideal keeps going up. After 5 minutes it is idling at 1500 rpm. I floor it a couple times to see if it drops-no go. Does the ECM control that?
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
Viking is correct on both accounts. Grab some beer, smokes and a couple of buddies. You will locate your problem on the first light and first beer. Pretty simple and stupidly accurate method.
Team Owner
Joined: Jul 2004
Posts: 28,459
Likes: 3,288
From: Hartford WI
When this happens, pull a hose off the manifold and block it. See what happens. If no changes put it back, When are are done, spray brake cleaner around the gaskets. See what happens. Any change and that is the looking point. I would prefer to do this with a scanner to see what the vital signs are based on the ECM and what it sees.
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Would also do this with a scanner hooked up to see what the ECM is seeing. IAC counts, TPS voltage at idle, target idle RPM all are in the datastream.
