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Thread: 2008 GMC Sierra trans question

  1. #1
    Member Spindoctor's Avatar
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    Default 2008 GMC Sierra trans question

    Sorry about the lack of specific RPO info on this post.
    VIN# 3GEK13Y18G258767
    This is a 2008 GMC Sierra 1500 4x4 with the 6.0ltr 15000 miles and a trans that I am not sure of as to the model. The vehicle was in 6 weeks ago for Dyno diagnostics.
    It has a very hard 1-2 up shift and a shudder under moderate load when going from 3 to 4.
    The dealer said they did not or could not feel anything wrong.
    When I tried to look at the system with my version 7.4 I could tell the data and PID stream were corrupt (Wrong info on wrong lines eg 15,000+
    rpm at idle). The ECM looked to be an E-38.
    So what I need to know is weather or not a newer version 7.5 or 8 would correct my data logging issues or is this a system that EFI Live has not yet worked out.
    The owner wants the data logs of trans pressures etc. so he can force the dealer to correct the problem or go Lemon Law on them. It is one of those vibrations that you don't notice at first but, once you do it always bugs you.
    For comparison his brother (or cousin) has the same truck and it has neither
    issue.
    As always- Thanks in advance- Tim H
    Thanks in advance- The Spindoctor (Tim H)
    Back ground-Mustang AWD500 Dyno- Over 500 tunes on systems including: Autronic, MoTec, AEM,COBB,Haltec, Electromotive,Greddy, Microtech (to name just a few)and now EFI Live!

  2. #2
    Forum tyhee Site Admin GMPX's Avatar
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    In the latest update there was a number of trans PID's added for the 6 speed (assuming that is what this trans is?). You will certainly need to update from 7.4.

    You will need to update to 7.5, you can find the download link HERE

    Update your EFILive system to build V7.5.5 build 82 by installing V7.5.5 Build 72 (which is what is in the download link) and selecting the Windows Start menu option:
    Start->All Programs->EFILive->V8->Tools->Check for New Updates.

    Cheers,
    Ross
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


  3. #3
    Lifetime Member Tre-Cool's Avatar
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    or run the v7.5 update program.

    v8 did nothing for me. updating 7.5 now though.

  4. #4
    Forum tyhee Site Admin GMPX's Avatar
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    Oh sorry, I put the wrong instructions up there, V8 is currently only used for managing firmware and files on the V2 hardware.

    Cheers,
    Ross
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


  5. #5
    Lifetime Member MN C5's Avatar
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    I didn't think the 6sp was available in a chevy until 09. At least I never found a 2008 OS for a 6sp VMax and was told by several service guys that the 6sp wasn't available until 09 in a Silverado.

  6. #6
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    GM info says it should be a 6L90E A6, if it is an LY6 6L gas engine. If it is an L76 6L gas engine, it should be a 4L70.

    Most likely the L76 in the 1500.

    The VIN looks to be incorrect too.

  7. #7
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    Quote Originally Posted by MN C5 View Post
    I didn't think the 6sp was available in a chevy until 09. At least I never found a 2008 OS for a 6sp VMax and was told by several service guys that the 6sp wasn't available until 09 in a Silverado.
    He said Sierra, could be a Denali right?

  8. #8
    Lifetime Member MN C5's Avatar
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    Quote Originally Posted by XLR8NSS View Post
    He said Sierra, could be a Denali right?
    The Denali has the 6.2 though right?

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