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Thread: 1.4T Sonic 6000rpm+ Issues (Rising boost, dropping MAF, etc)

  1. #1
    Advanced Tuner 383_Stroker's Avatar
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    1.4T Sonic 6000rpm+ Issues (Rising boost, dropping MAF, etc)

    Hey Guys,

    My wife got a 2012 1.4T M6 Sonic. We had it approximately two days before i decided to play with it. Haha. I've done some reading on here about the E78 tuning methods and have taken a shot at turning it up a little. I'm having a strange issue and i haven't been able to find the cause.

    Almost every time you run the car to redline, at 6,000rpm it noticeably noses over. You can see it actually loses 25-50 rpm for a moment when it does it. The boost starts to climb, the maf readings start to drop, and the car starts leaning out, it will knock if you stay in it as a result of high boost and a lean mixture, i'm sure.

    Attached is a screenshot of the issue and the tune as it sits.
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  2. #2
    Tuner in Training
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    Sounds very normal =) The 1.4 is not setup ( especially in stock form ) to handle or make high RPM power. The turbo is done in the 5500 rpm range, and on top of that - it is obvious that your car is a 2012 because you are running so much timing at 6100 RPM.

    These are low displacement small turbo engines- they just aren't setup to make power in high Rpms, so do yourself a favor and don't try to push the car above 5200 rpm ( especially on 91 octane )
    Doc
    Doc's Performance & Dyno Tuning - Las Vegas NV . Tuning any and all cars!

  3. #3
    Advanced Tuner 383_Stroker's Avatar
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    Well, i fully expected it to fall off as rpms rose, but this is like you tapped the brake at 6000 rpm, its just so sudden it didn't seem like it was gasping for air, haha.

  4. #4
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    Look in Engine > TM > Max Torque > Peak, Brake Torque Limit, and Overboost.

    That should get you started.

  5. #5
    Advanced Tuner 383_Stroker's Avatar
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    Quote Originally Posted by Flyer View Post
    Look in Engine > TM > Max Torque > Peak, Brake Torque Limit, and Overboost.

    That should get you started.
    I've made changes in all of those tables, changes that seem pretty moderate compared to what i've see others do. I guess whats throwing me is that the boost is INCREASING, while the maf airflow numbers fall flat on their face.
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