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1998 Ford F-150

Question: high idle when i first start truck

Question

Visitor, 4.6L V8, Whitehall, PA, May 16, 2011, 15:28

when i first start truck idle is high around 1500 rpms
to 2000 rpms then it goes up and down when it's warming
up then when it's warmed up the idle drops down to between
750rpms to 780rpms and holds steady i feel the idle is a bit
high on cold start up's the truck has only 65,ooo miles.

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  • Answer #1

    Brian Glastetter May 16, 2011, 18:21
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     Master

    The computer commands the Idle Air Control valve to raise the idle on cold start as a stategy of the PCM. If it is too high and fluxuating, a vacuum leak may be the most likely cause. We have had some isues with IAC valves creating high idles, but they usually do not fluxuate. The best method to diagnose this concern is to monitor the fuel trims and IAC duty cyle percentage with a scanner.

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  • Answer #2

    ronnieswindell May 21, 2011, 20:18
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     Rookie

    replace or clean idle control on motor

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