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Strange noise

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by slepy, Sep 29, 2009.

  1. slepy
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    slepy Extremely smart and handsome person. VCDS Map User

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    [Sep 29, 2009]
    Hi Guys,

    I've just spent some time in a bad traffic and have noticed a strange noise coming out from under the hood.
    I can hear it only on 1st and 2nd gear. It works in about the same moment when blow off valve in petrol engines. But instead of pssssss it is more like kkhhhh.:ohmy: So when I release accelerator (and I think I press the clutch) it goes khhhh. Plus it can be heard only when revs are going down from 2k rpm. I can't hear it when it goes down from lets say 2500rpm.

    I've got a visit booked in a garage on friday for service and overall check but need to drive to work for next few days and am not sure if it's safe.

    Anyone?:sos:


    update:
    I can hear it on 3rd gear as well. So I can assume that it is the same on all gears but it is hard to hear it at higher speed because of road noise etc.
    It does happen without releasing clutch as well. It just is more noisy when revs go down quicker so when I press clutch.
    It really sounds like some kind of valve or something.
    Last edited: Sep 29, 2009
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  3. slepy
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    slepy Extremely smart and handsome person. VCDS Map User

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    [Oct 12, 2009]
    Guys I really need help with that.
    I've put my car in VW/Audi specialist. They are saying that it is some kind of "induction noise". And it can be sound of something breaking down, but they can't find what it is.
    You can clearly hear it coming from air filter box. Now even on neutral.
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  4. Acidic32
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    Acidic32 A4 Cabriolet 1.8T Owner VCDS Map User

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    [Oct 13, 2009]
    Last time my engine made the Khhhh sound was a stuck Re-circ valve (induction)
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  5. slepy
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    slepy Extremely smart and handsome person. VCDS Map User

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    [Oct 13, 2009]
    Forgive my lack of engine knowledge.
    Is there something like that in diesel engine? If there is, how can I find it and check it?
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  6. Acidic32
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    Acidic32 A4 Cabriolet 1.8T Owner VCDS Map User

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    [Oct 13, 2009]
    Not sure, i know on the Audi Turbo petrol's they have one, not sure on the TDI sorry.
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