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1.9tdi - boost issue

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by twist123, Jul 5, 2012.

  1. twist123
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    twist123 Member

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    [Jul 5, 2012]
    Hi Guys,

    Having an issue with my B6 1.9tdi, a little while ago I was having boost issues so I replaced the vacuum hoses except the larger Turbo hoses and intercooler pipes. The issue is intermittent and goes away for a while but then returns, could be related to rain but Im not so sure as its always raining!

    Car was slow in the lower rev range where the turbo usually picks up at around 1600rpm it was dead, the weird thing is it only started picking up at around 2500rpm where it would boost but further into the rev range than usual.

    Ive changed the fuel filter, EGR, vacuum hoses, boost sensor in the plastic pipe at the top of the engine. I turned off the car unplugged boost sensor, no engine codes, next day its fine. This is so annoying as its really erratic.

    Any ideas?

    Thanks
    #1
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  3. twist123
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    twist123 Member

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  4. stu_m
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    stu_m Well-Known Member VCDS Map User

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    [Jul 10, 2012]
    I would get it scanned for any fault codes first
    #3
  5. twist123
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    twist123 Member

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    [Jul 10, 2012]
    No codes :( so havent a clue where to look.
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  6. pauldazzle
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    pauldazzle Active Member

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    [Jul 11, 2012]
    Doing some logging with VCDS should reveal the problem. MAF sensor failure is very common on VAG cars, & usually only throws a code if it's shorted to ground or become intermittent.
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  7. pj123
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    pj123 Member

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    [Jul 11, 2012]
    MAF can be duff without throwing fault codes - need to log using VCDS to check flow rate whilst driving.

    I would suspect sticking turbo vanes - see MR Muscle cleaning thread. There are some VCDS tests to check the N75 solenoid that controls the vanes.
    #6
  8. ScottD3
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    ScottD3 I want your faulty electronics Supporter

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    [Jul 11, 2012]
    Sounds like the same issue as my AFN TDI.

    I'm going with faulty N75 (no codes) or stuck VNT vains.
    Its currently getting its Aux belt replaced cause that snapped as well.

    If I find whats wrong with mine, I'll let you know.
    I'm keeping an eye on this thread just in case you find whats wrong with yours and it helps me. :)
    #7
  9. twist123
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    twist123 Member

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    [Jul 12, 2012]
    Thanks guys, Ill have a go at cleaning the VNTs first, then N75. Will update when I find some time to give them a clean.
    #8
  10. ScottD3
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    ScottD3 I want your faulty electronics Supporter

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    [Jul 16, 2012]
    Phone call from the garage.

    Car is now working.
    Replaced a couple of hoses and fitted my old turbo that I cleaned.
    All up and running better and quicker than before.

    Happy days [​IMG]

    #9

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