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Thread: boost bypass control??

  1. #1
    Tuner in Training
    Join Date
    Jun 2017
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    21

    boost bypass control??

    so i have been tuning my 2012 audi a7 since around november. car runs consistently 7.4s in 1/8 and 11.4-11.5s in 1/4. but i can not for the life of me figure out which table or tables control the boost bypass exactly. most times the bypass only closes (o%) when it shifts into 5th gear at top of pull. most of the pass it is around 5-15% open. commanded tq is around 750nm. if i change the airflow table to lets say 850. car just goes into limp mode and basically shuts down. any insight into this would be greatly appreciated. i just changed a bunch of stuff on the car and will need to redo the entire tune, so having a solid knowledge of this is a must at this point. i have added the tune and a 1/8 mile and 1/4 mile pull. as you can see, on this 1/4 mile pull the bypass opened alot causing boost to drop and my meth to turn off completely. thats why the lean issue and knock came in. thank you for your help
    Last edited by Hemithis01; 5 Days Ago at 10:11 AM.

  2. #2
    Tuner in Training
    Join Date
    Jun 2017
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    21
    So 22 people have looked at this and not one contribution? Has no one figured out full control of this system yet?

  3. #3
    Tuner in Training
    Join Date
    Dec 2019
    Posts
    27
    Cant tell you which table to adjust but if it is the same as the N75 on the Turbo cars 0% is wide open 100% is closed.

  4. #4
    Tuner in Training
    Join Date
    Jun 2017
    Posts
    21
    Ok so thanks to tyler coming to the rescue again!!! He has helped me a lot over the last few days. So there is not one single table that controls the boost bypass. It is controlled by the amount of torque requested vs actual torque. The ecu regulates the bypass to hit requested torque. So if your actual tq is higher than your requested tq. The ecu opens the bypass to try and lower actual tq output. If your not hitting the requested tq limit, then the ecu closes bypass in attempt to hit requested tq. If your actual tq is much higher than requested, the car will go into limp mode.