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Thread: Burst Knock?

  1. #1
    Tuner in Training
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    Sep 2013
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    Burst Knock?

    Trying to get my truck tuned up to where I can at least drive it when needed, will be a bit before I make it in for a dyno tune. Stage 2 cam, rebuilt bottom end, stock heads with a valve job. Motor is an lh6, aluminum block, 07 model with DOD delete. Starts idles and runs fine, no missing or obvious issues, but I keep having random knock that I can't get to go away. I've took out timing multiple times and it seemed to not change anything, so I even flashed the stock timing tables back in it and it still is doing the same thing. I'm not sure if maybe my knock sensors are picking up something they shouldn't or what the issue is. It seems to knock reliably when you first put the gas to it, before the rpms start rising. I would call it "tip in" but not sure if that's actually going to be called "tip in knock". Also at random times, usually after making a stop and letting the truck sit for 10-15 mins, when I start up and take off again, I get pretty big bursts of knock at random spots, that don't seem to replicate each time I'm in those cells. Think dialing in the fueling first would address some of this knock or do you think something else is going on? There's no audible knock and no I don't have any way to verify it's actually knock outside of my stock knock sensors currently.

    I've been reading on Burst Knock and I think that is what is happening at low RPMs when I step on the gas. How do I get it to go away? I see in other threads people disabling BK... Would that be the place to start to diagnose if it is actual knock or just burst knock? I've attached 3 logs and my current tune, does anyone have any suggestions on what direction I need to be heading with this?

    Thanks for any help!
    Attached Files Attached Files
    Last edited by ScarTissue48; 10-22-2021 at 12:11 AM.

  2. #2
    Tuning Addict blindsquirrel's Avatar
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    Turn it off - if it doesn't show any knock at tip-in then you don't need it anymore. If it does you can add it back little bit at a time until it doesn't happen anymore. I bet you will have no issues turning it off though.

    Burst KR is a predictive thing. On the stock tune with all stock parts and crap gas and the typical know-nothing driver, they predict that there will be some amount of knock so they pull timing before it can happen. Once you've started changing parts and eliminating the stupid PE delays and everything else that gets changed, that prediction of what's going to happen is no longer accurate.

  3. #3
    Tuner in Training
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    Will give that a shot. Thanks!

  4. #4
    Senior Tuner kingtal0n's Avatar
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    I always keep my burst knock active. It is a very useful feature which simply pulls timing briefly when the engine is suddenly loaded to allow the fuel system and enrichment strategies time to take effect, thereby giving a consistent window/margin of safety during a sudden transition.

    I find it extremely helpful for low RPM load transitions in a daily driver application with pump fuel because there are so many variables, as air temp and coolant temp can vary widely depending on how long you've been stuck in traffic with the A/C on and so forth.


    You don't need to let it pull a *lot* of timing, or for a long time. Or make it soo sensitive. You may Reduce the delay so it puts the timing back in quickly, and only let it pull a degree or two is better than nothing, and you can de-sensitize it so it only goes off under the most demanding conditional.

    It is a handy feature and I take advantage of everything the OEM ecu offers if possible, most stand-alone lack these type of intimate features.