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Thread: Can't flash lmm

  1. #1
    Junior Member maxtuner's Avatar
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    Default Can't flash lmm

    Hi guys , I'm trying to do a dpf delete on a friends lmm and now having some problems flashing it . I first pulled the stock tune and then tuned out the dpf and the truck ran perfect with no issues for about four months
    And now its throwing dpf related codes and its in reduced power mode . I looked the tune over and found I had not turned off all DTCs so I turned everything I could find related to dpf to "non emissions, no MIL" but now when I reflash , it doesn't make any difference at all . It erases and programs and says script finished successfully but truck stays in low power mode . I deleted the dpf on another lmm a few days ago and is working fine but this truck is not taking any changes I make in the tune . Can anyone help me out on this ? The truck needs to go to work and its very useless like this.
    My software and firmware are up to date as well
    05 gmc 2500hd CC,SB volant cold air intake
    Efilive, 4"mbrp turboback street scene front
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  2. #2
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    Found that any difference in pressure between the front and the rear of the DPF will cause this. Needs to be zero differential pressure before start up. Sometimes, dirt enters the pressure sensors and changes the static reading. Even one hundredth of an atmosphere will cause reduced power.

    Temporary fix is to increase power in reduced power mode.

    Hope that is helpful.
    Last edited by asmithIII; August 18th, 2014 at 11:18 PM.

  3. #3
    Junior Member maxtuner's Avatar
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    Ok thanks for the reply, how do you mean it's a temporary fix ? What do I do to fix permanently ?
    05 gmc 2500hd CC,SB volant cold air intake
    Efilive, 4"mbrp turboback street scene front
    Bumper

  4. #4
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    First scan to see if there is any difference in pressure before starting.

    My friend was satisfied with the temporary fix.

    Too soon to suggest buying or modifying differential pressure sensor.

  5. #5
    Junior Member maxtuner's Avatar
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    Ok I'll try that ad see where it gets me , the other problem is that the truck is 4 hrs from here ad ill only get to play with it on the weekend
    05 gmc 2500hd CC,SB volant cold air intake
    Efilive, 4"mbrp turboback street scene front
    Bumper

  6. #6
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    Took me a while to find that the only difference in my truck and friends was 1 kpa of pressure between front and rear of the DPF. The tubes to his sensor had been removed. Over time, dirt and dust entered sensor and resulted in a slight mis match in the reported pressure. I was unable to use EFI Live to remove or ignore this sight mis match in differential pressure without entering reduced power mode.

    Guess that professional tuners already know about this problem and have found a solution. Maybe a tune library would have a different DTC list to delete the DPF. Might find the DTC list to a hand held programmer that had DPF delete.

  7. #7
    Junior Member maxtuner's Avatar
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    Ok that makes a lot of sense but normally after a reflash the codes would stay off for a bit till it ran them through the system but now the engine light stays on the whole time and feels like the codes can't be deleted even with efilive now . So I was thinking I might have to limp it to a dealer and have them reflash a factory tune and start over . And if that should clear them then I should be able to turn off the dtcs with efi to keep them from popping up right ? Hope I'm not being really confusing here ... Haha
    05 gmc 2500hd CC,SB volant cold air intake
    Efilive, 4"mbrp turboback street scene front
    Bumper

  8. #8
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    Found a simple program with DPF delete for an LMM.
    Attached Files Attached Files

  9. #9
    Junior Member maxtuner's Avatar
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    How come the tune doesn't load in the tune tool? Since I've updated my software I can't load all lmm tunes anymore either
    05 gmc 2500hd CC,SB volant cold air intake
    Efilive, 4"mbrp turboback street scene front
    Bumper

  10. #10
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by maxtuner View Post
    How come the tune doesn't load in the tune tool? Since I've updated my software I can't load all lmm tunes anymore either
    Which V7 build version are you using...?

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