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Old 04-20-2007, 09:33 PM   #1
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Default wavering idle/IAC dying?

Tuning my MS setup, I'm still having idle issues even if I turn idle control back over to the stock ecu. Even with a stable AFR, it wavers between 700-1200 (regardless of cold or warm). Randomly idle can be steady at times and then sometimes it wavers. Occasionally the lower waver will cause the car to stall. It is not related to decel from coming out of gear as it can happen at a stop while idling or after a decel. It's almost as if the idle hunts occasionally.

Out of idle car is running fine, but the wavering idle is starting to get annoying. Maybe a dying IAC? Not sure, but I don't think it is MS related as it does the same when switched back over to the stock ECU. Any thoughts?
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Old 04-20-2007, 09:44 PM   #2
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does the spark advance remain fairly stable when it's doing this?
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Old 04-21-2007, 08:23 AM   #3
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BRG... does it suddenly stumble when sitting @ a light for 30secs? I think my IAC is on the way out again... but that's the symptom I'm getting.

Now.... when my IAC went the first time... what happened was the idle would bounce between 2K->3.5K... and it would also do that while in "cruise" (not on throttle, but still running car).

If you have a spare to swap to..... <G>

Dave,
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Old 04-21-2007, 01:48 PM   #4
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Al: Spark advance stays within +/-1 degree so pretty stable.

steelrat: It happens randomly which is why it's confusing. It can be right after coming to a stop or after sitting at idle for a bit. I think I'm going to see if cleaning out the IAC with some throttle body cleaner helps.
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Old 04-21-2007, 04:43 PM   #5
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Unplug the IAC connector and check the resistance on the IAC pins with a voltmeter with the car off. It should be 11-13 ohms. If its infinite then the coil is cooked.

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Old 04-21-2007, 05:24 PM   #6
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yeah, if the AFR and spark stay the same, the only thing it could be is the IAC, I'd guess. did you put the diode on the IAC wires for the MS?
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