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Thread: Knock sensors causing timing to be pulled DANGEROUS?

  1. #1
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    Knock sensors causing timing to be pulled DANGEROUS?

    My setup: m52 (.140 mls and arp's) on 91 pump and meth injection on a 6266
    Was doing some datalogging today on my "higher boost" setting around 17 psi and saw that timing was being pulled anywhere from 2-4 degree's throughout the rev range once in boost. Is this considered unsafe since some knock was being detected causing the timing to be pulled? Or is it just the knock sensors doing their job and pulling enough timing to keep the engine safe?
    96 328is turbo. Built 3.2, 6266, RSI Manifold

  2. #2
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    Contact your tuner..


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  3. #3
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    Quote Originally Posted by Willmartens View Post
    My setup: m52 (.140 mls and arp's) on 91 pump and meth injection on a 6266
    Was doing some datalogging today on my "higher boost" setting around 17 psi and saw that timing was being pulled anywhere from 2-4 degree's throughout the rev range once in boost. Is this considered unsafe since some knock was being detected causing the timing to be pulled? Or is it just the knock sensors doing their job and pulling enough timing to keep the engine safe?
    "Ideally" you would want 0 timing pull at all times.. so yes the ECU is doing it's job and keeping your engine safe. You should probably turn the boost down slightly or get a revision from your tuner though.

  4. #4
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    Tuner doesn't think it should be knocking either at the boost level i'm at with meth. I would say its still a pretty conservative tune with peak timing around 16.5* and high 10's on the afr gauge. I am wondering if my knock sensors are picking up a different sound in the engine bay or if they are simply going bad. I'm going to see if it still pulls timing on wastegate pressure of 10 psi and if it does that will tell me that the knock sensors aren't functioning properly.
    96 328is turbo. Built 3.2, 6266, RSI Manifold

  5. #5
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    Knock sensors causing timing to be pulled DANGEROUS?

    Quote Originally Posted by Willmartens View Post
    Tuner doesn't think it should be knocking either at the boost level i'm at with meth. I would say its still a pretty conservative tune with peak timing around 16.5* and high 10's on the afr gauge. I am wondering if my knock sensors are picking up a different sound in the engine bay or if they are simply going bad. I'm going to see if it still pulls timing on wastegate pressure of 10 psi and if it does that will tell me that the knock sensors aren't functioning properly.
    If the shells are intact, the knock sensors are not picking up another sound.

    There are a lot of reasons the car pulls timing. Your tuner should be able to look at the log and decide if it’s knock or not. Log the following: tps, load, current-knock, rpm, boost and afr.

    [edit: Added punctuation]
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    Last edited by vollosso; 06-11-2018 at 01:32 PM.
    1989 535i - sold
    1999 M3 Tiag/Dove - sold
    1998 M3 Turbo Arctic/black - current
    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
    2011 E82 135i - S85 Swap - current
    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  6. #6
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    There is no "one size fits all" tune. As recommended... take a log and send to your tuner and have him adjust accordingly. There is no such thing as working the other way around (you trying to curb knock by other means). It can very well be that your setup has a lower knock floor than other setups. It's not uncommon.

  7. #7
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    Quote Originally Posted by NOTORIOUS VR View Post
    There is no "one size fits all" tune. As recommended... take a log and send to your tuner and have him adjust accordingly. There is no such thing as working the other way around (you trying to curb knock by other means). It can very well be that your setup has a lower knock floor than other setups. It's not uncommon.
    Exactly


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    1989 535i - sold
    1999 M3 Tiag/Dove - sold
    1998 M3 Turbo Arctic/black - current
    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
    2011 E82 135i - S85 Swap - current
    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  8. #8
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    Makes sense. it was pulling around 4 degree's of timing at some points when it was hitting around 16*. That would mean it was sensing knock up until like 12*. (16* "stock tuned" setting and then pulling 4 degrees on top of that) 12* at 17 psi with meth injection seems like it would be well below the knock threshold, but I can understand what you are saying how every setup is different. I'll be talking with my tuner as well.
    96 328is turbo. Built 3.2, 6266, RSI Manifold

  9. #9
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    IAT and humidity are a huge contributor to knock tendency as well.

  10. #10
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    Quote Originally Posted by Kevin325i View Post
    IAT and humidity are a huge contributor to knock tendency as well.
    IAT's pretty much never exceed 100 degrees with meth and its only around 70 degrees outside where I live
    96 328is turbo. Built 3.2, 6266, RSI Manifold

  11. #11
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    Try a bigger meth nozzle perhaps.

  12. #12
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    It could be the distribution of meth to each cylinder is not equal.

  13. #13
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    Quote Originally Posted by chikinhed View Post
    It could be the distribution of meth to each cylinder is not equal.
    Most certainly it isn't (and often overlooked issue).

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