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Thread: Is the 14.7:1 cruise AFR target on M156 REALLY hard coded?

  1. #1
    Tuner in Training
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    Nov 2016
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    Is the 14.7:1 cruise AFR target on M156 REALLY hard coded?

    Is the 14.7:1 cruise AFR target on M156 REALLY hard coded or is it just a flag or table that has not yet been discovered by HPTuners?

    This large capacity high compression engine has huge pumping losses and I'm desperate to get the light load stuff to around 15.5:1 to reduce pumping losses. I've had great success with doing the same on other vehicles.

  2. #2
    Tuner in Training
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    Jun 2019
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    i have yet to try this or lean burn for the M156, but from what I've experienced with my Audi A4 B6, the Motronic ECU has this hard coded as a safeguard for that vehicle.

  3. #3
    Tuner in Training
    Join Date
    Nov 2016
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    38
    I've had a reply to my old ticket and there are some new tables to try in the latest beta

    They only work for one ROM firmware by the looks. Only a 2014 example file I have shows them so they're working on adding them to the others.

    I can't wait to try them. If we can target 1.04:1 at idle and 1.08:1 at light driving loads and cruise, economy should improve substantially and no more catless smell and black stuff. I've seen big improvements on even much smaller and lower compression engines. The gains should be even more profound on an M156. Timing will need to be added to suit as the leaner you go, the slower the flame front speed.

    Target Lambda Adder.jpg