Low Engine Idle Speed - Need Help
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Joined: Jun 2003
Posts: 60
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From: Pikeville TN
Low Engine Idle Speed - Need Help
I need some help on this one. I only have this one little problem with my '95 vette but it's driving me crazy. The engine idle speed is too low, down around 400 with car in drive and A/C on stopped at a red light. It shakes so bad I keep thinking it's going to die. Even without A/C on and in Park it only idles at 500 and shakes a little. According to my local repair shop, the idle speed is controlled by the PCM and there is no adjustment. Huh? Surely there is some way to set the low idle up a little bit without replacing the entire PCM. Anybody else had this problem?
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Joined: Mar 2004
Posts: 212
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From: Fairfax VT
Re: Low Engine Idle Speed - Need Help (pkvvette)
Hi,
Based on what I know you have a ECM controlled part called an IAC. IAC is the Idle Air Control valve. It is controlled by the ECM and may be clogged up and not operating correctly. I had just the same problems with my 87 and I took off the throttle body and cleaned it up real good. I went to AZ and bought a new IAC valve and installed it after the cleaning. The motor now runs perfectly. It is possible that you have an idle correction screw (like mine) but you sould not have to adjust it. Just cleaning the IAC valve is not worth the effort. AZ gets about 25 to 30$ for a new one. Hope this helps and good luck.
Regards,
Don in VT :flag
Based on what I know you have a ECM controlled part called an IAC. IAC is the Idle Air Control valve. It is controlled by the ECM and may be clogged up and not operating correctly. I had just the same problems with my 87 and I took off the throttle body and cleaned it up real good. I went to AZ and bought a new IAC valve and installed it after the cleaning. The motor now runs perfectly. It is possible that you have an idle correction screw (like mine) but you sould not have to adjust it. Just cleaning the IAC valve is not worth the effort. AZ gets about 25 to 30$ for a new one. Hope this helps and good luck.
Regards,
Don in VT :flag
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Joined: May 2001
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Re: Low Engine Idle Speed - Need Help (pkvvette)
:iagree: It is controlled by the computer, but everything has to work. The IAC may be malfunctioning or just really dirty. I believe that the idle of the car should change if it's running and you pull the connection from the IAC. If nothing changes it's a safe bet that the IAC isn't functioning properly.
When you turn on the AC the IAC is supposed to open up a little more to compensate for the load. You can remove the IAC and carefully clean it up. If this doesn't work you may need to replace it. In any case I'm sure it's nothing major.
When you turn on the AC the IAC is supposed to open up a little more to compensate for the load. You can remove the IAC and carefully clean it up. If this doesn't work you may need to replace it. In any case I'm sure it's nothing major.
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Joined: Jun 2003
Posts: 60
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From: Pikeville TN
Re: Low Engine Idle Speed - Need Help (pkvvette)
Thanks for the info guys. I believe you both hit the nail on the head. The vette is at shop right now having a new alternator put on and I told the mechanic what you guys had suggested. The IAC was filthy and when disconnected, nothing changed on the idle speed, so looks like its a good bet that'll fix it. What a great board!!!! You can't get this kind of info anywhere else. Thanks again! You made my day!
