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Thread: Air Flow Rate limit

  1. #1
    Lifetime Member izaks's Avatar
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    Default Air Flow Rate limit

    PID: Air flow rate from Mass Air Flow sensor (Grams/s) maxes out at 655.35 . I have increased the value of UNM-16-11 (gps), but it made no difference to the logged maximum of 655.35
    6.8L supercharged high boost running E38 at 10,100+ hz
    Is this a hard coded limit or is there a way to increase the limit
    2011 VE SSV 417 + CAM + Whipple 2.9FF SC + NOS + PPV front struts + Bilstein rear shocks + 6L90E with single piece carbon fibre prop

  2. #2
    Forum tyhee Site Admin GMPX's Avatar
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    Default

    I can't think of that PID name off the top of my head but '655.35' certainly calculates out (with scaling) to the maximum limit for an unsigned 16bit value (65535).
    It will have a scaler of 0.01 so that is where the 655.35 comes from, unfortunately that is all controlled in the ECM code.
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  3. #3
    Lifetime Member izaks's Avatar
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    Sorry, SAE.MAF
    2011 VE SSV 417 + CAM + Whipple 2.9FF SC + NOS + PPV front struts + Bilstein rear shocks + 6L90E with single piece carbon fibre prop

  4. #4
    Lifetime Member izaks's Avatar
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    I logged GM.AIRPERSEC, and it logs past the 655.35 limit
    2011 VE SSV 417 + CAM + Whipple 2.9FF SC + NOS + PPV front struts + Bilstein rear shocks + 6L90E with single piece carbon fibre prop

  5. #5
    Forum tyhee Site Admin GMPX's Avatar
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    Glad you found an alternative, the SAE limit is just the limitation of that PID.
    See here:
    https://en.wikipedia.org/wiki/OBD-II_PIDs

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    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.


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