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Flat spot on full boost

Discussion in 'A3/S3 Forum (8L Chassis)' started by 1animal1, Dec 10, 2010.

  1. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    It's been a while chaps :)

    Okies just started to notice an issue at the top of the rev range when the cars boosting fully, the car seems to get to a certain point then starts juddering, the power drops off and a quite loud tssss.

    So far i have disconnected the MAF, that didnt do anything, checked the top hoses, going to change the N75 tomorrow to see if that does owt, N249 is already bypassed..... already have uprated DV....plugs are only 6 months old.....and i see have the Lamba fault coming up every now and again (still not got around to resolving that)

    ideas? i'm hoping it isnt a manifold leak or something worse
    #1
  2. S3 Paul
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    S3 Paul Active Member

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    I would see if the lambda fault is back,
    Failing that... do some logging with vag com while the car is doing this
    #2
  3. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    already cleared the lamba fault for second time mate, not come back but still doing this.....lamba shouldnt cause this though should it?

    Not a great deal i can log afraid, only have restricted freeware :(
    #3
  4. S3 Paul
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    S3 Paul Active Member

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    what operating system on laptop??
    vista? 7? or xp?
    #4
  5. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    Vista.......
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  6. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    update...lamba replaced today by JBS, cleared the fault but still leaves me with the problem......

    due to go back in to JBS next Sat for diagnostics, tracking and MOT.....this thing is costing me again!!!
    #6
  7. Sandip
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    Sandip Active Member

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    Could it be a coilpack breaking down maybe?
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  8. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    id have thought that would have flagged a boost mate.... replaced all coils couple years ago so wouldnt imagine so

    its weird, it only occurs when im requesting full boost, as in 3rd gear 3krpm...it just pulls back and judders as it gets to the full boosting point...the juddering continues until full boost isnt attainable?

    hard to explain :)
    #8
  9. Optimum Tuning
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    Optimum Tuning www.optimumtuning.co.uk

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    Hi there make sure you check the vac pipe to the fuel pressure reg on the fuel rail hasnt dropped off/ split. I have come across this before, obviously causes lambda faults to flag up and the EXACT symptoms you have. Let me know what happens!:yum:
    #9
  10. finesse
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    finesse Active Member

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    tiiiiiiiiimy

    vagcom log:

    log 002 115 119
    #10
  11. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    Cheers for you're help chaps,i put my old plugs back in this morning and noticed bank 4 was out a couple of turns - thanks to paul for the suggestion

    Must invest in a torque wrench :)
    #11
  12. finesse
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    finesse Active Member

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    fickle! bet your back in love with teh S3....AGAIN :)
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  13. Nilz
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    Nilz Defo worth the wait :)

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    Tim, are you all sorted now??

    I had the same on mine, turned out it was the fuel pressure regulator pipe, had literally split off the bottom of the manifold, replaced with a silicon pipe and all is back to normal.
    #13
  14. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    yup cheers chaps...and John yeah it is my friend again :) funny how a problem like this makes you love it even more when its back working again, always feels faster than it was!! :)

    I'll go back into the hole i was sleeping in now, see you all soon :)
    #14
  15. Nilz
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    Nilz Defo worth the wait :)

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    Back into hibernation
    #15
  16. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    i thought id let you catch up on the post count mate ;)
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  17. Welly
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    Welly VX220 SC Driver :)

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    Thanks for coming.... lol.
    #17
  18. 1animal1
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    1animal1 The Clar!! it mouves!!!

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    quote of the century ;)
    #18
  19. Welly
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    Welly VX220 SC Driver :)

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    :thumbsup:
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