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Low idle issue

Discussion in 'Engine & Drivetrain' started by Hammer02, Apr 12, 2021.

  1. Hammer02

    Hammer02 TYF Newbie

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    Wish I could!
     
  2. Hammer02

    Hammer02 TYF Newbie

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    No bad fuel im sure
    No codes on the injectors
    Ran fuel system cleaner with premium for 2 full tanks.
    Dont know about the TC but the trans feels and shifts smooth.
    All vac lines seem fine
    Dont know if the intake mani cracked.
     
  3. Hammer02

    Hammer02 TYF Newbie

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    She pulls as hard as ever.
    kinda why I let it go all winter.
     
  4. Hammer02

    Hammer02 TYF Newbie

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    I take anything thats in the way out right away..Cause If I dont It seems to end up taking longer.
     
  5. fasteddy

    fasteddy Full Access Member

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    If you've checked all your vacuum lines and everything looks good.
    And your truck runs fine otherwise, you may just want to swap out the throttle body for a new one.
    Maybe something is bad on the TB and not opening enough at the bottom, when your throttle pedal position is 0.

    Then if that doesn't work, and if you have access to tuner software like HP Tuners, you can bump up your target idle to 900 and see if that
    takes you back to 700. I've done that before....temporarily until i got the tune right on a new cam....LOL

    But I'm telling ya, if you shave those heads, put in a new cam and tune it, that will fix it for sure......LOL
     
  6. jonnytahoe

    jonnytahoe Full Access Member

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    About the only thing good about a '00 and '01 is the manual throttle body.
     
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  7. Jimmyy

    Jimmyy Full Access Member

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    K.I.S.S have you check the idle speed with a scan tool? The needle could be off on the gage. “Warm air at idle”, is the engine temperature high? Is it better with a cool engine?
     
  8. Doubeleive

    Doubeleive Supporting Member

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    I drove mine to 324k sold it about 4 years ago last time I checked it was still on the road
     
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  9. Hammer02

    Hammer02 TYF Newbie

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    Cold it runs right
    But when the truck hits near operating temp, back down to 500.
     
  10. fasteddy

    fasteddy Full Access Member

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    That's a clue!

    The computer with stock tune will adjust your idle based on
    1. coolant temp (over/under 90 degrees is a change point)
    2. whether the A/C is on or off
    3. Whether its in gear or not (Park/Neutral as opposed to Drive)

    So try some combos and get back

    Like
    When coolant gets 180+
    Come to stop
    Check Idle
    If 500 (stock is 550) Yours maybe lower. Without a digital gauge its hard to tell.
    - turn off A/C
    Check Idle
    - if still 500
    -put in neutral
    Check Idle

    Try to pin point the scenario where idle falls below operating level to run your a/c while getting tacos/burritos at drive thru.
    Like can you go through the drive thru with A/C on and if you put it in Neutral idle goes back up?

    When Cold or coolant under 50
    - idle should be 800 with A/C on or off and in gear or not.


    How long did you own it before it started doing this?

    How many miles are on your 6.0L

    Are you running back in AWD, or in some kind of axle delete 2WD?

    You should get HP Tuners and look at the tune. If the previous owner put strange parts in it
    he also may have changed the tune. People do strange things.

    But your Denali worked fine after you got it then this low idle issue started to occur...correct?

    But....
    When I first got my Tahoe I looked at the tune for the engine and transmission.
    They had "De"tuned the transmission because it wasn't shifting right due to excessive wear on some parts.
    The tried to get the computer to compensate for the trans needing work.....stupid patch.
     

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