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Knock Sensors and Timing Pull

Discussion in 'A3/S3 Forum (8L Chassis)' started by Alex C, Nov 14, 2012.

  1. Alex C
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    Alex C Well-Known Member

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    [Nov 14, 2012]
    Background:
    Standard Engine S3 8L AMK
    Fault Code: EGT sensor - being fixed next week
    Rattely clacking head: I think this is either cam chain or tappets - hopefully being fixed Wednesday next week

    Anyway, today i went out and logged it, i didnt do any hardcore 100% load 0-redline pulls just drove it around normally in traffic in and out of town logging.

    I knew already i was suffering from timing pull so i logged [003, 026, 020]

    block 26 are the knock voltages and block 20 is the timing pull block

    Here is a plot of timing pull against engine speed:

    [​IMG]

    so its cylinders 3&4 that are getting timing pull

    But when plotting the knock sensor voltage against engine speed:

    [​IMG]

    it is the knock sensor on cylinder 2 that looks abnomal

    Am i right to be confused here or should i just travel hopefully?

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    Last edited: Nov 14, 2012
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  3. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Nov 14, 2012]
    knock voltages alone dont tell the picture..
    CF correction resultant accounts for the windowed knock regitration not just voltages.. which swing about a lot... I've seen 30v! and no CF
    #2
  4. Alex C
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    Alex C Well-Known Member

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    [Nov 14, 2012]
    thanks Bill,

    I know i don't have the logs posted but what might cause timing pull only on cylinders 3&4 on part throttle?
    #3
  5. superkarl
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    superkarl MAN OF STEEL

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    [Nov 14, 2012]
    if you have an egt fault wont your fueling be abit off.
    mine was, i was very rich for quite a while.
    That fault might have something to do with your CF. just a thought, but once its fixed then do your logging again to see if there is any change.
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  6. Alex C
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    Alex C Well-Known Member

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    [Nov 14, 2012]
    Thanks Karl. yeah i will do, i am hoping that either the EGT or renewing the timing chain will fix it but i figured that both of those faults would affect all four cylinders rather than just the two.

    Maybe its tappets on those cylinders or maybe both of them coincidently have problems with piston rings?
    #5

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