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Thread: LY6(6.0) swap high idle and zero timing issue.

  1. #1

    LY6(6.0) swap high idle and zero timing issue.

    I swapped a stock 2009 ly6 into my 2011 GMC Sierra and I am having a issue with a higher than normal idle (commanding 600 but its idling at 800-1000) and I am seeing near zero timing when its in park. As soon as I put it in gear, the rpms drop real low and there's a 50% chance the truck will stall. When I start it back up, everything is normal again and it drives fine. It will idle at 600 and it has 10-12 degrees of spark. Any idea what is causing this and why it only happens on a initial startup? Again, it is a bone stock ly6 motor and I Just copied all the tables from a stock 2010 2500 series Silverado (6.0) file from the repository over to my tune file and flashed it. Only changes I made to the tune are for injector data (swapped in my 5.3 flex fuel injectors), PWM cooling fans (2500 have a manual fan) and the stock transmission settings for my 6l80e. Truck is throwing a P0507. I have tried a different throttle body and checked for vacuum leaks already. Any help would be greatly appreciated. This is my current tune file Stock ly6 Tune.hpt. This a log of it idling, stalling and then re-starting it. 21-10-17 13-52-46.hpl

  2. #2
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    It's pulling timing to reduce the idle speed, because for some reason it can't close the throttle any more than 23.14%. Looks mechanically stuck or blocked from closing.

    At initial key-on (no crank), do you hear the throttle body do the normal click-clack noise as it forces the blade to fully closed then back to the at-rest position?

  3. #3
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    Try a throttle clean reset with the scanner.

  4. #4
    Quote Originally Posted by blindsquirrel View Post
    It's pulling timing to reduce the idle speed, because for some reason it can't close the throttle any more than 23.14%. Looks mechanically stuck or blocked from closing.

    At initial key-on (no crank), do you hear the throttle body do the normal click-clack noise as it forces the blade to fully closed then back to the at-rest position?
    I'll have to check but I did try replacing the throttle body with another used one I had laying around but that did not help.

  5. #5
    Quote Originally Posted by 2xLS1 View Post
    Try a throttle clean reset with the scanner.
    I tried doing that but I didn't notice anything. Is there any special procedure?

  6. #6
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    Quote Originally Posted by TAPyvehc93 View Post
    I tried doing that but I didn't notice anything. Is there any special procedure?
    KOEO>connect scanner>click button

  7. #7
    I believe you may have a vacuum leak. The ecu is ripping timing out to try and lower the idle. I just went through this.

  8. #8
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    If the throttle position were down at 1-2% and idle speed was still up at 1000 with timing around 0*, I'd agree on vacuum leak. But the log shows TP at 24-25% indicating the extra air is coming from the throttle blade being open too much. It should be idling high with the throttle open that far. It's either not trying to close the blade or it can't close the blade, and I don't think there's a way to determine which it is without all the relevant ETC & idle channels being logged.