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Thread: Knock retard and acceleration jolt

  1. #1

    Default Knock retard and acceleration jolt

    So i've been getting a jolting problem which randomly occurs when accelerating. It's as if fuel has been cut, but it's not.
    Since i've got my ap, i've been monitoring KR and noticed that usually when it jolts, it's knock, though sometimes it's not knock (yet to log this), but just looses power for a brief moment and then kicks back in again (very weird).

    In this first log I was on WOT, and I noticed that for some reason the AFR's are WAY too high. This is not always the case, but on several times when i've logged this knock, afr's have been around these values, not dipping when I go on WOT. Also noticed fuel trims are kinda crazy too.
    this is a ots stage 1 sf+tih+ic map


    In the second log, it is the same map. This time I was not on WOT, rather around 20% Throttle Position and not on boost what so ever. Would expect afr's to be as they are in this log, and the fuel trims aren't crazy like in the other log this time. I have NO IDEA whatsoever as to what would be causing the knock in this log.

    Any thoughts/help would be appreciated.
    I will strive to do a MAF cal as soon as I can to try clear that side of things up and smooth it out, but for now i'm a little confused as to why I'm getting all this knock!

    Cheers.
    Attached Files Attached Files
    --> 2008 Metro Grey Sports Pack Gen1 <--

    CS SRI ll CS TIP ll CS AB ll 2XS SSP ll 2XS FMIC ll SURE Anchors ll Enkei RPF1's 17x9 +45 ll Lamin-X Fog Tint ll DBA T3 4000 series ll Remsa pads ll Braided lines
    CP-E S2 RMM ll Hankook RS3 235/40/17 ll Forge V1 BPV ll Whiteline RSB ll AutoTech HPFP
    ll Spin-on Conversion ll Rear Diffuser
    DGR Coilovers ll LED Replacement lights ll "08-MPS" plates ll Cobb AP V3 (E85) ll CP-e TBE ll OCC






  2. #2

    Default

    Here is another log I found I did. this log had no jolt whatsoever. Didn't feel a thing, yet knock went on for ages (~2s) before I even noticed it.
    Again around 20% throttle, so no boost. Not sure what caused it..
    Attached Files Attached Files

  3. #3
    Join Date
    Apr 2010
    Location
    Canberra
    Posts
    9,459

    Default

    first log: this was a 3rd - 4th pull right? should have kept the previous parts in... but your AFR went to 14.5 and boost was 14psi... hence the knock
    although, the fact it just stopped rather than "decayed" says to me there is something moving in your engine bay that triggered the knock sensor

    2nd: was this log started from a cold start? if so, cold engine is a high possibility, time says 221 second (less than 4 mins) i ignore any/all knock for first 10 minutes of driving until engine warmed up (and coolant temp is ~180F)

    3rd is same guess (sub 60s)
    Newbie FAQ My Build Thread
    From stock, to GT3071, to substantially less modded, many lessons learned!
    3" HTP | 100 Cel DP | Autotech HPFP | AP V3 - Self Tuned on E20 | JBR RSB | CPE S2 REM | JBR Shifter Bushings

  4. #4

    Default

    Ok, none of these were WOT logs as such, they were driving around and the knock that I was getting.

    They were all on a warmed up engine, and taken in the middle of the night.

    Here is a 3rd gear and a 4th gear WOT log.
    oddly enough they are perfectly fine..

    Just not sure why the AFR in the previous log was not dropping on WOT.
    You said it could be something moving in the engine bay giving false knock readings, how can you determine if this is the case?

    Also attacked a 0-120 log, again, it's fine.. Very weird
    Attached Files Attached Files
    --> 2008 Metro Grey Sports Pack Gen1 <--

    CS SRI ll CS TIP ll CS AB ll 2XS SSP ll 2XS FMIC ll SURE Anchors ll Enkei RPF1's 17x9 +45 ll Lamin-X Fog Tint ll DBA T3 4000 series ll Remsa pads ll Braided lines
    CP-E S2 RMM ll Hankook RS3 235/40/17 ll Forge V1 BPV ll Whiteline RSB ll AutoTech HPFP
    ll Spin-on Conversion ll Rear Diffuser
    DGR Coilovers ll LED Replacement lights ll "08-MPS" plates ll Cobb AP V3 (E85) ll CP-e TBE ll OCC






  5. #5
    Join Date
    Nov 2008
    Location
    North side, Vic
    Age
    37
    Posts
    6,745

    Default

    The joys of modifying a car!
    I chased something similar for ages, turned out the last thing I checked should have been one of the first - had a fouled plug.

    Sent from my GT-I9505 using Tapatalk 4

  6. #6

    Default

    Plugs are fine... it's just the weird afr that's got me confused

    Sent from my LG-P880 using Tapatalk 4

  7. #7

    Default

    Hi gibba.
    I've recently just had the same thing happen any idea what your problem was

  8. #8

    Default

    Bugger, this happens to me on the odd occasion too. Argh, sometimes it lasts for 10seconds.

  9. #9

    Default

    just got the AP and a stage 1 map and I'm getting weird knocks like u too.. mostly part throttle. Any updates Gibba?


    Sent from my iPhone using Tapatalk

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