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Thread: Please help - KR driving me insane!

  1. #1
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    Please help - KR driving me insane!

    I'm hoping that someone can take a look at these logs and help me figure out how to avoid so much KR during high-speed, low-throttle situation!

    From these logs, it seems to me that I should either setup the tune to downshift or at least release the TCC sooner than it does now. Seems like the KR is caused by "bogging". I've attached (2) logs, my current tune and my scanner config files (v2.24 scanner). Please help! Removing timing doesn't seem to be the solution.

    20160207_CustomTune-TCC-Changes-v1.73.hpt
    VCM Scanner.cfg
    2012Impala-IgnitionTiming-NEW2.cfg
    012216_CustomTune-ManyTransChanges-v.73-HospitalToMargheritas.hpl
    012216_CustomTune-ManyTransChanges-v.73-FromMargheritas.hpl

    Thank you in advance!

  2. #2
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    Post something about what you are trying to tune and what's been done to the engine.
    Hib Halverson
    Just Another Tuner in Training.

  3. #3
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    Car is bonse stock mechanically. What I'm trying to tune is to get rid of the KR that happens at high-speed, low RPM (it's clearly visibile in the logs). It seems to happen most when I push the pedal to try and maintain a highway speed or accelerate slowly at highway speeds. I'm thinking that maybe the tune should be altered to unlock the TCC or downshift during those type of situations to avoid the KR - but not really sure to be honest...

  4. #4
    Tuning Addict 5FDP's Avatar
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    It's harmless KR in those situations though, it's not a high rpm, high load where damage could happen.

    Run 93 octane for a tank, see if anything changes.
    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.

  5. #5
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    Hmm - so KR isn't really a big deal unless you are under high-RPM, high-load situations? I just hate seeing all of that KR in there! :-)

    I actually run 93 octane at all times.

  6. #6
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    Can you cause knock by *removing* too much timing - or can it only be caused by adding too much timing?

  7. #7
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    Taking away timing is not bad, just robs power/ torque. Taking timing off should be the easiest way to remove the KR. Its not an exact one to one ratio for knock retard. Sometimes for every 1 degree of KR you need to take off 2 degrees of timing. You cannot get knock from less timing. Just take off a few more degrees of timing. Are you changing both the low octane and high octane charts?
    2005 Buick Allure (Lacrosse for dem Americans )

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  8. #8
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    Take away timing?!?!?! F that. Turn down for what? lol. Clean your intake valves with some top end spray (Seafoam or CRC). Mine got misfires and KR to the point of the engine going into limp mode when mine needed cleaning. Even with catch cans on both PCVs I still suck in oil. Stupid GDI engine. In my tune I bring in PE a lot earlier than stock and made the EQ ratio a bit richer to help a bit with the mid range. Stock PE engagement is ridiculously delayed.
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  9. #9
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    I've had my intake valves cleaned by a dealership and it made absolutely no difference whatsoever.

    If you have KR, taking timing away can actually increse power. If you are seeing 5 degrees of KR, you may be able to avoid the KR completely by removing 2 degrees of timing in that area. Plus, you'll avoid the knock to begin with. Higher timing is not always better...

    I don't get any misfires - just KR. I've eliminated a lot of the KR by shifting into 6th a little later and not lockign the TCC utnil a few MPH after going into 6th (during low-throttle situations). Basically, the KR was being caused by "enging lugging" situations.

    I get VERY little oil in my intake. Even though we have the same engine, the tune and setup of the engine are very differernt. Believe it or not, intake valve deposits don't seem to be a major issue on the 3.6L LFX Impalas.... Still haven't heard a single person complain a about any drivability issues realted to "valve coking". It does seem to be a bigger issue on some 3.6L cars though...

  10. #10
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    Ah. Forgot you have an impala. I realize reducing timing when experiencing kr can help power in those areas but I just don't think we should have to run less timing than stock. I run 93 octane with occasional cleaners/booster. Dealer actually said gm recommends it for the LFX which are having issues with coked valves and kr.

  11. #11
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    Do you have your stock tune file so i can compare to your modified tune file? See if I can give any helping advice.

  12. #12
    Tuner in Training xpbr2000's Avatar
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    i was sent this by a friend some time back. I don't have issues with KR yet so i haven't really used it. but its a good read and may help you with your KR

    http://www.hptuners.com/forum/showth...cks-Guide-quot

  13. #13
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    For what it's worth, I ended up getting rid of the vast majority of my "random" KR by simply modifying the shift points and even moreso, my TCC apply/release settings. After analyzing log after log, I started seeing the trend of KR happening when applying slightly more throttle while cruising at speeds of 40mph+ (5th or 6th grear) when the TCC was locked. By simply unlocking the TCC quicker in those type of situations (or applying it slightly later), I got rid of the vast majority of my KR. The KR was simply being caused by "engeine lugging" - even more than I realized.

    It used to be that taking a somewhat short dirve of mixed country roads and highway roads, I would see considerable KR (up to 8 degrees of KR). Now, I rarely see any KR during those same drives - and when I do see KR, it 2 degrees or less). It's a significant difference...