Question about 1989 Honda Prelude

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Idle irratic the car has irratic idle when the temp. of outside air is cold summer time it is ok . no intake leaks so what can I do?

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  • cowboy5717 Nov 07, 2008

    so is thier a way to check the iac valve? or do you just replace and hope? thanks



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Could be the IAC (Idle Air Control) valve. I had a similar problem on my old integra in the winter and that was the problem. It's on the intake manifold and for the older integras i know is kinda common.

Posted on Nov 06, 2008

  • Steve N
    Steve N Nov 07, 2008

    What I have done before is taken the intake tube off and opened up the throttle plate and sprayed carb cleaner or brake cleaner in there aimed at the IAC valves to try and free them up and sometimes it works, sometimes it doesn't. The unit has little valves in there and over time carbon deposits build up and can cause the valves to stick or clog up a little restricting air and whatnot. It's worth a try for only the price of the can of carb cleaner. Just don't spray way to much in at once. The car may also take a couple crank over's to start, that's normal...that just is when the carb cleaner is working its way through. Hope this helps



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you skipped the #1 fact, hot or cold or both?
EFI runs in MODES. cold is one , hot is another.
if coolant fails to reach proper temp, the thermostat is bad.
or installed wrong.!
I'll toss dice and land on HOT.

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This car has EFI,
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1: thermostat (coolant) is bad and wont hold 180 to 200F temps.
2: ISC (idle speed controller, dirty and sticks)
3: IAC (some cars have this and it can stick open0
4: throttle cables set wrong.
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a: motor good, check compresion.
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I know for sure you have air leaks.
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