Low Rpms

Discussion in '94-04 V6 Mustang' started by 99v6mustang, Nov 29, 2008.

  1. 99v6mustang New Member

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    Hey there, just made this account very new to cars and all, im 17 and fell in love with mustangs, have had an 84 5.0L that i bought and sold and now have a 99 3.8L v6 manuel.. this is were i ran into a problem..

    My RPM is normal when i am stopped, but if im moving at any speeds and push my clutch in sometimes the rpm will drop to about 500, it doesnt happen all the time but iv noticed it happening more often. Any ideas what could be wrong? Thanks.
    99v6mustang, Nov 29, 2008
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  2. MustangLX-5.0 Founding Member

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    How long does it stay down near 500 rpm? Does it ever seem like it's going to stall out? It sounds like your IAC (Idle Air Control) isn't working correctly.It may be sticking closed.How does the car run when you first start it up?
    MustangLX-5.0, Nov 30, 2008
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  3. 99v6mustang New Member

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    Itll stay at 500's untill the car is stopped ( if im moving) then it may take 2 or 3 seconds them jumps back up to the normal.. its only stalled twice with this happening.. i was doing at 40 ish and had to slam on the brakes and with the clutch in it went to 500 and just slowing went down till it stopped..

    When if i first start it nothing is wrong, runs just fine.
    99v6mustang, Dec 1, 2008
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  4. MustangLX-5.0 Founding Member

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    I'm gonna have to say the idle air control is sticking.I can't think of anything else it could possibly be.Does it run rich,hesitate ever,run rough,idle fluctuate up and down? Check Engine light ever come on?

    How many miles?

    If none of the above apply,then just replace the IAC valve.

    Just another FYI in case you didn't know.The IAC is an electronic valve located on the throttle body.It varies the ammount of intake air to the engine when your foot is not on the gas pedal.Which basically adjusts your "off-pedal" engine RPM's.

    Now that you know...
    MustangLX-5.0, Dec 3, 2008
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  5. 99v6mustang New Member

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    lets see, its hesitated twice that i can think of.. going from second to third. i dont know what it was but just took it out and put it back into gear and was fine, (thinking i missed it) iv had to fluctuate from around 600 to 800. when stopped for just a couple of seconds. its got a little over 91500 miles and the check engine light has never come on.

    Well thanks for the help.. works out since i planned on replacing my throttle body this summer,

    Thanks again apperciate the help! :)
    99v6mustang, Dec 4, 2008
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