Several Necessary Questions
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
Several Necessary Questions
My 1986 Vette is not running as well as it should. If I set the timing it runs fine until I reconnec the EST cable. Then the ECM take over and the idle tends to be around 1000RPM. This seems a little high.
My latest theory is that the Electronic Air Contidioning (new for 1986) is causing the ECM to think that the compressor is on when it really isn't. Does anyone have experience with this?
Next, if the above isn't the problem and I am not getting any serious error codes then how do I test to see if the ECM is bad?
My latest theory is that the Electronic Air Contidioning (new for 1986) is causing the ECM to think that the compressor is on when it really isn't. Does anyone have experience with this?
Next, if the above isn't the problem and I am not getting any serious error codes then how do I test to see if the ECM is bad?
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
You need to check the TPS voltage, probably also need to remove the TB and then clean the IAC valve. Both contribute to the idle directly.
Instructor
Joined: Feb 2002
Posts: 139
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Check out www.C4vettes.com as this will help you dial in to seeking the codes for your car. This site also covers many other pieces of information re: C4's
Good luck.
Good luck.
