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Low Idle after Rebuild

97 Views 2 Replies 2 Participants Last post by  mzbinden
I’m struggling to get my son’s 1998 Acura Integra LS to idle right after our rebuild. Idle maxes out around 500-550, despite idle screw adjustment (with IAC wire disconnected). This also makes it hard to get timing right.

No CEL. Engine runs.

Not sure where to diagnose next, and don’t want to start randomly swapping out parts if not necessary. Could it be bad IAC valve? Are there other symptoms to indicate that?

Rebuilding this as my son’s first car. We have torn it completely apart. Had engine machined and bored, but we tore down and rebuilt ourselves. Lots of new parts along the way, but did not replace IAC valve. Link to my post on first engine start. Had no issues starting and driving, but idle has always been an issue.
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First, what is your idle speed with the IAC disconnected? Did you set it to 480, but it increases to only 550 when you plug the IAC back in? If that's the case, it's pretty obvious your IAC is either clogged or simply not working. If the idle picks up at least a little when plugging in the IAC, I'd try soaking or spraying some carb cleaner through it before replacing it.

As for getting the timing right, RPM is irrelevant other than that it is high enough for the engine to run smoothly. You could use a clamp on the throttle cable to force the revs up if you need a higher speed for better stability. When the service connector is jumped, idle speed is locked, regardless of RPM.
Facepalm moment...problem finally solved. Found in another thread to double check the IACV connection and make sure you didn't swap with another connector which is identical. And of course that is exactly what I did. Swapped the two and's purring like a kitten. Can't believe it took me so long to identify that.

And @rguttenb - you're completely right about RPMs and timing...was just harder with engine not running smoothly on its own. But now all sorted!
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