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Car shaking when idling

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Burt25, Jun 15, 2006.

  1. Burt25
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    Burt25 Member

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    I have a 2001 Tdi 130 which is shaking when I'm sitting in traffic (goes away when I increase the revs and also when I turn the steering wheel slightly) The needle on the rev counter sits perfectly level. I have run diagnostics and found no problem. Took the car to my local mechanic and he told me it was a dirty fuel filter - fuel filter replaced and system flushed, but the problem still exists.

    Does anyone have any ideas? Could it be worn engine mounts?
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  2. timboukvw
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    timboukvw Member

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    try bottom pully by power steering pump i know of a mk3 golf that had same problem and it was the pully that was making it shake.
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  3. Aldo
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    Aldo Active Member

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    Mmm.

    I have a 2.0 FSi and get exactly the same problem, it's every now and again, QRSport advised it's like this on all FSi's and they said take it to Audi as it was not showing a fault on their diagnostics. Perhaps it may be this then as you have a Diesel and have the same problem?
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  4. technics100
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    technics100 Member

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    Its probably the passenger side engine mount. On the later TDi's the mount has a solenoid which controls the rigidity of the mount..

    the way the mounts work is that there is a fluid chamber with a plastic body in the middle of it, with small channel cut through it. this allows fluid from the top chamber, through the plastic body, to the bottom chamber. the bottom chamber is rubber lined and can deform under pressure. there is also an airway vented to atmosphere, with a rubber membrane separating the fluid from the atmosphere. a solenoid valve, controlled by the motronic, can open or close the airway.

    below 1100 rpm (i.e idle), the engine vibrations are not enough to force fluid from the top chamber, through the passageway to the bottom chamber. the airway is open (solenoid valve open). the rubber membrane creates a soft cushion which absorbs the high frequency vibrations.

    above 1100 rpm the soleniod valve is closed which blocks the airway and so "hardens" the mount (the fluid has nowhere to go). thus the mount is effectively solid.

    the high frequency vibrations at speed are absorbed by the membrane (as in the idle case), while the more damaging low frequency vibrations cause the fluid to force itself through the chamber in the plastic body to the lower chamber, forcing the (lower) rubber chamber to distort - effectively absorbing the vibrations.

    in this case i would suspect that the mounts are bad - possibly as simple as the connectors have been pulled off.
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  5. griffj
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    griffj Member

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    technics100
    could you roughly point out at all the posiition of this valve in the bay at all,
    as i have a 2003 passat 1.9 TDI and it seems to have this fault, and i want to check if it has one fo these valves fitted.

    also,
    whats the deal with the pully?
    where is it positioned and ehat do i need to look for,

    cheers mateypeeps.
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  6. dstech
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    dstech Member

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    I have a petrol 3.0L and I had a bad vibration at idle. I had the power steering pump replaced and the issue has gone away. It's been about 3k miles since the service and so far so good. I don't know if this is the same issue because my car didn't "Shake" like it had a small block V8 in it, but rather a very harsh vibration that could rattle your teeth.
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  7. technics100
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    technics100 Member

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    The solenoid valve is located in the passenger side engine mount. it has the standard audi plug on it. It was showing an error with on vag-com, I just replaced it with a standard mount as a mate had one lying around. its number 7 in the picture..

    [​IMG]
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  8. griffj
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    griffj Member

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    how easy was it to replace bud?
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  9. technics100
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    technics100 Member

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    Its quite easy, about 30 mins all in, I took off the top and bottom supports to make it easier.
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