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Thread: Part throttle knock retard driving me crazy.

  1. #1
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    Part throttle knock retard driving me crazy.

    Hello all, first-time tuner on a 6.2 L92 swap into a 79 Jeep Cherokee Cheif. Running a Texas Speed VVT stage 1 cam, LS3 intake and injectors, LS7 MAF in a custom intake. 2.5" dual exhaust with high flow cats and an H-pipe.

    Currently working on getting my MAF dialed and I have the low-frequency table pretty dialed (HF needs work.) I am seeing a bit of knock retard between 1,500 and 3,000 RPM. I've done some timing tuning to try and stop it, but at this point, much of my table is lower than a stock 6.2 corvette that I'm using for a comparison file, and I'm still seeing 1-2 degrees of KR in my logs.

    Is there something I'm missing? VE is disabled, and the KR doesn't seem to correlate to A/F beside the fact it doesn't happen at all in PE.

    Also, can anyone recommend a good mail-order tuner to help with this stuff? I've tried one already and communication has been less than stellar...

    cheif log timing way down.hpl
    part throttle knock edit 5.hpt


    advance.PNG
    knock retard.PNG
    LTFT.PNG
    STFT.PNG
    Last edited by monkeyevil; 07-12-2020 at 04:36 PM.

  2. #2
    Tuning Addict 5FDP's Avatar
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    No vibrations or rubbing of any kind with the headers or things like that?

    Are you running 91+ octane??

    I would disable burst knock on something like that too.

    Low speed, low load knock is pretty common from what I see in many of the earlier 6.2 trucks. If all the easy stuff is known to be good like vibrations and good fuel, you could make the knock sensors less sensitive to see if goes away. The 1-2 degrees spikes at random wouldn't really bother me at all, it's not causing any harm.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Advanced Tuner jsllc's Avatar
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    Quote Originally Posted by monkeyevil View Post
    Hello all, first-time tuner on a 6.2 L92 swap into a 79 Jeep Cherokee Cheif. Running a Texas Speed VVT stage 1 cam, LS3 intake and injectors, LS7 MAF in a custom intake. 2.5" dual exhaust with high flow cats and an H-pipe.

    Currently working on getting my MAF dialed and I have the low-frequency table pretty dialed (HF needs work.) I am seeing a bit of knock retard between 1,500 and 3,000 RPM. I've done some timing tuning to try and stop it, but at this point, much of my table is lower than a stock 6.2 corvette that I'm using for a comparison file, and I'm still seeing 1-2 degrees of KR in my logs.

    Is there something I'm missing? VE is disabled, and the KR doesn't seem to correlate to A/F beside the fact it doesn't happen at all in PE.

    Also, can anyone recommend a good mail-order tuner to help with this stuff? I've tried one already and communication has been less than stellar...

    cheif log timing way down.hpl
    part throttle knock edit 5.hpt


    advance.PNG
    knock retard.PNG
    LTFT.PNG
    STFT.PNG

    need to log cyl/airmass. just finishing tuning a car that had these symptoms. knock sensor was bad and had grounding issues.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm