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Thread: Low RPM Knock driving me crazy

  1. #1
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    Low RPM Knock driving me crazy

    Hey Guys,

    I am having trouble with some little low rpm knock. In order to verify this issue I even went back to my Stock file with KAM reset - still receiving some little knock with that. Maybe this is even in an acceptable tolerance, as the file now is plane stock exempt for MAF and rear O2 shut off.
    Can anyone confirm this, or even has a complete stock logfile were this is also the case.

    My mods are JLT CAI, Kooks catted Header, aftermarket cat back active Exhaust system.

    The file attached is plain stock, exempt for MAF Period and O2 Sensor control.
    Log is attached as well.


    Thanks Mark
    Attached Files Attached Files
    Mustangklinik.de

  2. #2
    Senior Tuner
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    I see the same thing on a car I've been tuning. I put a 50/50 E85 mix in that car and it still occurred. Your knock is less than his but still make sure everything is tight on the exhaust and nothing is making contact anywhere that would make noise.

    At one point we got 8 degrees knock retard with really no throttle input as soon as letting off the clutch to pull out. This car has a noticeable noise at one muffler but a lesser noise would likely cause the same thing just with less knock retard.
    16-07-05 17-31-03.hpl

  3. #3
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    I actually do not believe something is hitting somewhere in my case. As the motion of the engine is much stronger when it is driven hard - and here we do not have any knock.
    Spark source says torque control or base in most cases the knock occurs, therefore I did not test to adjust the corresponding borderline tables as they are stock anyway.
    I am also a little confused about spark source "torque control" is this still Borderline spark ?
    Mustangklinik.de

  4. #4
    Advanced Tuner
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    I get 7-10* of KR in low load low rpm from time time, even on a e40 mix. I lowered spark values for those loads and RPM and it still registered the KR, found out my X pipe was rubbing under low loads on the driver side. Won't rub under high loads though.

  5. #5
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    After some more testing with taking back global spark to some major degree, it realy seems that in my case it is also related to some little rattle of the exhaust system. It seems that under some conditions there is a little vibration or swinging in the exhaust system itself (not even touching the chassis) that causes this.
    Last edited by G-Town-GT; 07-12-2016 at 01:19 AM.
    Mustangklinik.de

  6. #6
    Senior Tuner
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    Nothing is making contact on the car I was referring to earlier either. The noise is either coming from the hanger or the actual muffler itself. Without taking the muffler off and shaking it to listen for a rattle it's difficult to tell.