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Thread: High idle

  1. #1
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    High idle

    I am new to HP tuners working on a LS sea into a 1950chevy pickup. The motor is a 4.7 out of a Chevy pickup. I have everything hooked u and running. The IAC is acting up. When I start the truck the motor rams up to 2800 RPM. I have checked for vacume leaks and found nothing. Currently using a stock tune with security turned off and all HO2sDTC turned off. Any hel is appreciated.

  2. #2
    Tuning Addict 5FDP's Avatar
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    If the engine ramps way up to 2,800rpm with the throttle blade completely closed, then that sounds like a huge vacuum leak.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Verify the throttle blade is closed all the way and not hanging up on something.

    How did you check for vacuum leaks?

  4. #4
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    Quote Originally Posted by 5FDP View Post
    If the engine ramps way up to 2,800rpm with the throttle blade completely closed, then that sounds like a huge vacuum leak.
    I have checked for vacuum leaks. I pulled the intake, inspected it and changed gaskets. It is most definitely ramping up due to the IAC valve. If I unplug it the engine idles back down to 1100 ish. The tps is showing .04% when idling.

  5. #5
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    Quote Originally Posted by Evo8john View Post
    Verify the throttle blade is closed all the way and not hanging up on something.

    How did you check for vacuum leaks?
    While the engine was running sprayed carb cleaner around the intake. No change in RPM. Pulled intake off inspected runners for cracks and replaced the intake gasket.

  6. #6
    What is the IAC stepper count at idle?