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What else can it possilbly be..!!!

Discussion in 'A4/S4 forum(B5 Chassis)' started by richie_jones, Jan 24, 2009.

  1. richie_jones
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    richie_jones Member

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    [Jan 24, 2009]
    My car (1.8T AEB) has had an annoying engine judder when laying off the accelerator, its as if the engines choking up. Its really hard to discribe. If you try and floor it during this period the engine has no power and you have to lay off the pedal for a few seconds then everything is ok.

    I`ve replaced the turbo, then replaced the new turbo due to a blocked oil feed pipe (I know i should of changed it). I`ve replaced the MAF, Intake hose, Cleaned the throttle body and run an adaption using vagcom. Also replaced the spark plugs and changed the engine oil.
    The problem is intermittent and show No fault codes in vag com.

    Anyone any ideas...

    Cheers
    #1
  2. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Jan 24, 2009]
    Fuel pump or fuel pump relay maybe as the fuel gets shut off during lift off. Or is it more of an actual feelable judder?
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  3. richie_jones
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    richie_jones Member

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    [Jan 24, 2009]
    The judders not mechanical in the terms of suspention/engine mounts if you know what i mean. Its like a misfire judder.
    Its something to think about fuel pump/relay but i`d expect a fault code to show up....
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  4. stub
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    stub the matrix is comin

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    [Jan 24, 2009]
    i know its a long shot but could it be the module between the ecu an the coils. it sounds like how mine started an then 1 went totaly an had to replace it at a cost of £200 including fitting but it didn't show up on the vagcom.
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 24, 2009]
    The fuel pump doesnt stop during overrun, its just the injectors that turn off.

    I'd be looking at the stuff that takes fine control of the fuelling, CTS and lambda sensors to start with, and some new plugs, correctly gapped, nothing fancy just some NGK BKR6E's will do.

    The other possibility might be a sticking injector, which would cause fuel to continue to enter one or more cylinders when in overrun, which when you open the throttle again basically means its far too rich to burn properly. Are any of the plugs sooty?
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  6. jcb
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    jcb Active Member VCDS Map User

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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 24, 2009]
    hmm yer good point

    There are some points that are known for going, like the Z shaped breather that comes off the block. Worth going over all the pipework closely though

    And i'd do a vagcom scan if you havent already, just to check if its logged anything.
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  8. richie_jones
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    richie_jones Member

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    [Jan 25, 2009]
    Ok cheers guys gonna take another good look at the points you`ve suggested..

    Stub whats the module called between the ECU and the coils...

    Aragorn.. CTS ? (cooling temp sensor?)
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  9. stub
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    stub the matrix is comin

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    [Jan 25, 2009]
    i can't remember the name of it but its a little black box that sends the rite firing order to the coil then plug. i'll try an found out an let you know later today
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 25, 2009]
    stub your thinking of the ignition amplifer. It sits on top of the airbox, with two plugs going into it, and a plastic cover thing with a vent in it over the top.

    CTS is coolant temp sensor, its mounted in the water gallery at the rear of the cylinder head, with a blue or green plug.

    Do you have vagcom?
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  11. richie_jones
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    richie_jones Member

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    [Jan 25, 2009]
    I`ve seen this module in the air box when changing the MAF, Just looks like a heat sink from inside the air box lid.

    Yes i have vag com but think its 3.11 version
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  12. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 25, 2009]
    3.11 is fine, does it see anything wrong?
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  13. richie_jones
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    richie_jones Member

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    [Jan 25, 2009]
    No mate no fault codes.

    I`d just like to add that when driving slowly up a hill in the wrong gear , say 3rd instead of second the car completely dies, it doesn`t cut out but has no power and would grind to a stop if you didn`t change down a gear.
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  14. richie_jones
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    richie_jones Member

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    [Jan 27, 2009]
    Anyone any more ideas?
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  15. AUDI TURBO
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    AUDI TURBO Member

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    [Jan 27, 2009]
    you describing exactly same fault i had on my aeb 1.8 turbo it was igniton coil amplifier. it what basically tells your coils to go on/off. mine went faulty and it o#would start coil 3 but then never spark agin. 50 quid from local part shop
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  16. richie_jones
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    richie_jones Member

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    [Jan 27, 2009]
    Did your problem mainly happen on overrun....
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  17. richie_jones
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    richie_jones Member

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    [Jan 27, 2009]
    Was your problem mainly on overrun....
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