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Thread: Turbo 6.1 Hemi - Odd "Shudder" when increase boost

  1. #1
    Tuner in Training
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    Jun 2010
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    Turbo 6.1 Hemi - Odd "Shudder" when increase boost

    I have a 76mm turbo on my otherwise stock 6.1 hemi. Idles great, drivability is good, it runs absolutely perfect at or below 9 psi of boost. When I start turning the boost up above 10 psi I am getting a weird shudder at WOT that is audible and you can feel the loss of power. Raising the boost from 9 to 12 is actually lowering my 1/4 mile .4 seconds. Plugs are gapped at 0.028, running on E85. Logs show no knock at either boost level.

    My tuner is out of ideas so I am reaching out here to see if others may have experienced this.

    No_shudder_log.hplShudder_log1.hpl
    2006 Jeep Grand Cherokee SRT8 / 76mm turbo / E85 / Dings VB (Stock longblock)
    10.1@132

  2. #2
    Tuner in Training jefo's Avatar
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    Jul 2022
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    The logs look pretty close except for added boost in 3rd gear, and it looks like this is when the shuddering starts. Timing and fuel are constant so it seems like classic spark blowout; Might be worth gapping the plugs down a bit and seeing if it goes away.
    Last edited by jefo; 08-23-2022 at 10:50 PM.

  3. #3
    Tuner in Training
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    I noticed that my total airflow goes nuts when i increased the boost. Could that cause any issues?
    2006 Jeep Grand Cherokee SRT8 / 76mm turbo / E85 / Dings VB (Stock longblock)
    10.1@132