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Thread: GM Gen 3 2 Bar OS with MAF and SD together

  1. #1
    Tuner in Training
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    GM Gen 3 2 Bar OS with MAF and SD together

    I hope this is the right spot to get attention from the admins? If not I apologize in advance. Trying to drill down on a problem with the 2bar OS on a Gen 3 GM p59 ECM.

    You can tune MAF alone fine and VE (SD) fine and dynamic looks good in both (when turned off). As soon as dynamic is enabled then it drops and pulls the tune to lean.

    I have had a couple people help, but right now it looks like a software OS problem not a tune problem. I?ve attached a sample tune and log as well.

    Can one of the admins please confirm the problem? I would like to know whether this is possible or not possible. Either or just to move on.

    Thanks,

    Jonathan 1 Combo Final.hptCombo Log 1.hplMAF Only 6.hplVE Only 7.hpl

  2. #2
    Senior Tuner Ben Charles's Avatar
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    The custom OS says JUST SD only

    Saying that, I have blended them before just depends on OS. But I would do just pure SD when using custom OS

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  3. #3
    Tuner in Training
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    Thanks so much for the reply. It helps to know that it is only possible maybe on some. I am about 90 percent sure now it cannot be blended on mine.

    I can blend below boost so I have rpm SD cut off set to 1400 rpm. After that it is all MAF. Since airflow is pretty linear after this it seems to work well. I get the added benefit of the SD at low rpm then as well.

    I have always gotten better fuel economy with the MAF in play so that is why I really wanted to blend them. This is a 16,000 lb motorhome so throttle transitions are not fast.