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idle is fast how do i adjust it

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 88bblazen, Jul 9, 2004.

  1. 88bblazen

    88bblazen Registered Member

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    my idle is running fast on my 88 blazer its got the tbi on it how do i adjust it /forums/images/graemlins/k5.gif /forums/images/graemlins/ears.gif
     
  2. skratch

    skratch 1/2 ton status

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    I can't find the other post on this but I did copy the last part about how to do it:

    [ QUOTE ]

    "Take the paper clip and open it up and form it into a big "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' pins.

    Turn on the ignition, but don't start the engine. Wait 30 seconds. Now, go remove the connector from the IAC.

    Start engine. You are now going to adjust "minimum air". There is a Torx screw on the side of the throttle body. This is what needs to be turned to adjust minimum air, or more commonly known as "idle speed". It comes from the factory with a protective metal cap over it. If the cap is still there, use a small punch to knock it out. Set the idle speed to 450 rpm, rotating the Torx screw clockwise to raise rpm, and counter-clockwise to lower rpm. Once the idle rpm is set, turn off the engine.

    Re-connect the connector onto the IAC. Start engine. Idle speed is now once again governed by the ECM, but your idle should be smooth and steady, approximately 600 rpm in Drive (for unmodified cars).

    If you set an SES light by having the IAC disconnected, then after shutting down the engine disconnect the negative battery terminal. Wait 5 minutes. This will clear the ECM of all trouble codes. Re-connect the battery and drive the car for 20 minutes to allow the ECM to relearn your driving style""



    [/ QUOTE ]

    hope that helps ya /forums/images/graemlins/thumb.gif
     
  3. duece21

    duece21 1/2 ton status

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    How fast is it running? Have you checked for leaks at the base of the TBI unit? Spray some carb cleaner at the base of the throttle body and if the Idle surges then its the gasket. Need to also check the IAC valve. pull it out and see if is stuck. Can use brake clean to clean it.

    Hope that helps a little.. /forums/images/graemlins/waytogo.gif
     
  4. Bob87Burb

    Bob87Burb 1/2 ton status

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    [ QUOTE ]
    I can't find the other post on this but I did copy the last part about how to do it:

    [ QUOTE ]

    "Take the paper clip and open it up and form it into a big "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' pins.

    Turn on the ignition, but don't start the engine. Wait 30 seconds. Now, go remove the connector from the IAC.

    Start engine. You are now going to adjust "minimum air". There is a Torx screw on the side of the throttle body. This is what needs to be turned to adjust minimum air, or more commonly known as "idle speed". It comes from the factory with a protective metal cap over it. If the cap is still there, use a small punch to knock it out. Set the idle speed to 450 rpm, rotating the Torx screw clockwise to raise rpm, and counter-clockwise to lower rpm. Once the idle rpm is set, turn off the engine.

    Re-connect the connector onto the IAC. Start engine. Idle speed is now once again governed by the ECM, but your idle should be smooth and steady, approximately 600 rpm in Drive (for unmodified cars).

    If you set an SES light by having the IAC disconnected, then after shutting down the engine disconnect the negative battery terminal. Wait 5 minutes. This will clear the ECM of all trouble codes. Re-connect the battery and drive the car for 20 minutes to allow the ECM to relearn your driving style""



    [/ QUOTE ]

    hope that helps ya /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    It helps me! I've been doing it with the truck in gear, setting the idle to 750 rpm. I got that info from a "GM certified tech" that my dad knows. Looks like he was wrong!

    Thanks!
     
  5. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Wow, 450 seems really low. I don't think my motor would idle very well at 450. I set mine for 750 or so in park, but I didn't have a shop manual or anything... Is this from a shop manual, or did someone just write this up themself?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Thats out of the camaro service manual IIRC.

    I'd have to look in the manual, but there are probably specs for TBI and TPI. I imagine they are the same or that would be mentioned in the write up, but that obviously doesn't apply to manual trans rigs, so if someone took that from the manual, that must only be part of it.
     
  7. Blue85

    Blue85 Troll Premium Member

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    I've heard that if the idle is erratic, it can be from the common problem of worn bushings on the throttle blades, which doesn't let them close right.
     

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