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Intermittent Turbo Audi A4 2.0 FSI

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by psd99, Aug 27, 2012.

  1. psd99
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    psd99 Member

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    [Aug 27, 2012]
    Hey all,

    I've only had the car since July and over the weekend I covered around 300 miles. (first proper long journey)
    I did two long 100 mile journeys. I noticed yesterday and today that the turbo will sometimes not kick in.
    It was quite quick before in the first and second gear (3rd to 5th rev) , but it doesn't always feel like a turbo now.

    I had my cambelt changed recently (6th August)
    when I went to the car the VAG specialist had the car plugged into the computer and he said that there was a problem with my AC and intermittent turbo - but at the time I had no problems. He then said it is probably because the sensors had been reset when they changed the cambelt, reran the rest (I think and no problems- he did this within minutes)
    This was 3 weeks ago.

    So the first question is what the VAG specialist said is that correct - can the sensors give a false positive?

    I had a read on this forum and see it is a common fault. I need one of those devices to read the fault codes.
    Should I be concerned with this? What could make the turbo intermittent?

    BTW 61K on the clock.
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  3. psd99
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    psd99 Member

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    [Aug 27, 2012]
    Is there anything in the engine to stop someone from ripping the **** out of the engine and turbo?

    I found myself testing this 10 times today and maybe 4-5 times it had no power.

    I'm thinking perhaps because I was testing too hard, the turbo might have been disabled.
    #2
  4. Chris Norman
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    Chris Norman New Member

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    [Aug 27, 2012]
    The car will go into limp mode when its not happy. This will limit boost hence it feels like the turbo has stopped working. This can be caused by a whole host of things such as fuelling or boost leak.

    Best thing to do is get it connected to vag com and check for any faults.
    #3
  5. psd99
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    psd99 Member

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    [Aug 27, 2012]
    thanks

    when it goes into limp mode - will I notice anything on the dash? i.e How do I know it is limp mode?
    #4
  6. psd99
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    psd99 Member

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    [Aug 27, 2012]
    of course loss of power :(

    maybe the engine got hot
    I could live with the car like this, but ought to get it checked out I might have bought a lemon :(
    #5
  7. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Aug 27, 2012]
    it will cut power so you dont **** it up
    hence limp home
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  8. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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    [Aug 27, 2012]
    you could live with your car going in to limp loss of power ?
    get a mini
    #7
  9. psd99
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    psd99 Member

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    [Aug 27, 2012]
    Well not dangerous to drive around like this so in that respect i would be ok

    But i fear that the loss of power will become greater, i see your point so i will get it checked out


    Will see how it drives in the next week though
    #8
  10. Molnboman
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    Molnboman Well-Known Member

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    [Aug 28, 2012]
    Sorry for hijacking the thread. Do petrol cars go into limp mode.....I thought this only applied to diesels?

    Could someone confirm.

    Cheers
    A
    #9
  11. psd99
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    psd99 Member

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    [Aug 28, 2012]
    I am Fairly sure that
    both diesel and petrol cars go into limp mode
    #10
  12. psd99
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    psd99 Member

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    [Aug 30, 2012]
    Performance is okay now still fairly powerful

    Just felt laggish after the long journey oh well

    took it to the garage and there
    There was no fault or error from the VAG console
    i saw him running the test
    #11
  13. northernlight
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    northernlight Member

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    [Aug 31, 2012]
    Could be the diverter valve. If that was going then wouldn't show up as fault code and would feel like no boost.
    #12
  14. dannyboy75
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    dannyboy75 Member

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    [Aug 31, 2012]
    Agreed, if it feels more like 150-160bhp than 200, then it's probably the diverter valve. I had this when I bought my TFSI last year. No fault codes or engine light, but it felt no faster than my previous car (Alfa 156 JTS) when I first got it.

    £50 for a new DV from ebay, and the difference was unbelievable.
    #13
  15. psd99
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    psd99 Member

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    [Aug 31, 2012]
    Thanks guys so how do u diagnose that the valve is a problem?
    dont really know how to fit that valve

    Any guides? Not really engine competent
    #14
  16. dannyboy75
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    dannyboy75 Member

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    [Aug 31, 2012]
    For the sake of £50 for the part, I just took a punt and risked it. It was immediately obvious after the new one was fitted that the old DV was knackered - the rubber membrane splits and leaks boost pressure.

    I didn't fit it myself as I'm pretty useless with cars (computers are more my thing), so just got a local mechanic to fit it. From memory it was only an hour's labour or less.

    P.S. AFAIK, the only way to diagnose it would be to remove the existing DV and inspect it for tears in the membrane, if you don't want to risk the £50 on a new part first. The new part should be a revision D, which has apparently been redesigned to be more durable.
    #15
  17. dannyboy75
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    dannyboy75 Member

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    [Aug 31, 2012]
    #16
  18. psd99
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    psd99 Member

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    [Aug 31, 2012]
    #17
  19. psd99
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    psd99 Member

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    [Aug 31, 2012]
    #18
  20. psd99
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    psd99 Member

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    [Aug 31, 2012]
    I seen some videos of how to change the valve
    looks doable here
    #19
  21. psd99
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    psd99 Member

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    [Aug 31, 2012]
    #20
  22. razza1
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    razza1 Well-Known Member

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    [Aug 31, 2012]
    Got one sat in the boot of my car, need to get round to fitting it really...
    #21
  23. psd99
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    psd99 Member

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    [Aug 31, 2012]
    Are u competent enough to fit it yourself?
    Fancy doing mine too please. Lol
    #22
  24. weekenny
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    weekenny Member

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    [Aug 31, 2012]
    If its not your Dv try your N75 boost control valve as mine failed and gave similar symptoms.

    Both valves can be bought from Audi Dv around £60 the N75 around £20
    #23
  25. psd99
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    psd99 Member

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    [Aug 31, 2012]
    Thanks if there was a problem with. 75would the n75
    produce an error code?
    #24
  26. weekenny
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    weekenny Member

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    [Aug 31, 2012]
    Yeah mine would sometimes throw a code to say the boost limit was not reached.
    #25
  27. brasiliangringo
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    brasiliangringo Member

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    [Aug 31, 2012]
    What you need to do is check the Rosstech VCDS user map on here (if you are in the South i can assist) and offer someone a few beer tokens and they will scan your car and reveal specific fault codes eg faulty N75 / run a boost test. That's the 1st place to start.
    #26
  28. psd99
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    psd99 Member

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    [Aug 31, 2012]
    Thanks already did that please read above


    Wl get the dv changed
    im excited lOl
    #27
  29. brasiliangringo
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    brasiliangringo Member

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    [Aug 31, 2012]
    You make a vague reference to it yes, but from the code the computer provides, reference material on the web will point you to precisely what components to check 1st.

    Eg im not suggesting this is your code but to get an idea of what i mean:

    17964/P1556/005462 - Ross-Tech Wiki
    #28
  30. psd99
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    psd99 Member

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    [Sep 19, 2012]
    Thanks guys

    The valve has arrived but not fitted yet

    Seen a video on utube but the valve is in an awkward place to get to underneath the car

    So How much should it cost to replace the valve?

    Btw does the valve always work when i use the right foot or will it only kick in certain times?
    reason I say it because initially I always feel a kick and power but after engine been running for a while
    the power feel is different more gradual and missing the kick feel
    #29

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