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rough idle after new cambelt (-2.50 torsion value)

seabee05 Sep 29, 2013

  1. seabee05

    seabee05 New Member

    Hey guys Bit of a tricky one here I've currently just taken my a3 To audi for a cambelt and ever since I've had a slightlt rough idle but my mpg has been really good at least 20% better than previously. I've checked the torsion value on vcds and its at -2.50 when warm is this within normal boundaries? The car has always been a bit difficult to start when warm also but that's been for years now. Any experts got any answers? I don't wanna phone Audi if its not a big problem lol.
  2. RobinA3

    RobinA3 Well-Known Member

    I would certainly ask them to double check the timing - it could have easily be a tooth out on the cambelt.
  3. max69vk

    max69vk Active Member

    -2.5 torsion needs adjusting. It should be between 0 to 0.5, once this is done the rear cam needs to be adjusted (position wise) to match, this will sort out the rough idle.

    Your MPG figures will be showing a lot better but won't have actually changed that much as the readings will be calculating based on your old sensor readings & cam positioning etc so in reality they won't be correct. You may have actually gained some MPG thanks to the cambelt change as this should have bought the valve timing back into line (rather than injection timing as the ECU controls that).

    The TDI's can be really sensitive to even the slightest adjustments. A .35 degrees adjustment on the inlet cam yielded me proven 4MPG improvement & much smoother throttle response too.
  4. seabee05

    seabee05 New Member

    Thanks for the response Max, I took it back to vw today and spoke to the "master tech" who assured me they changed the belt with a special cam locking tool pin, ( I already knew this) I then mentioned the torsion value showing -2.5 on vcds and the response I then got was that the cams aren't adjustable. I then replied yes they are he said no they are not I said yes they are..... After a few moments of who's right he agreed the pulleys where adjustable. He then offerd to check the timing and low and be hold he said it was perfect And that vcds is not proper vw diagnostic software, after feeling fobed off I feel I should pursuit this but don't know what the best option is, I can't force this dealership to fix my issue so my idea is to maybe take it to a competitor vw dealership and see what they say?

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