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Jet black fuel filter and minor cold start issue

Discussion in 'A3/S3/Sportback (8P Chassis)' started by the obese penguin, Jun 21, 2013.

  1. the obese penguin
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    the obese penguin Member

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    [Jun 21, 2013]
    Car is a3 2.0 tdi 170 bmn with dpf and egr removed..

    As above the fuel filter was jet black when I last changed it approx one month ago and the car has cold start issue..

    After the car sits for 6-8 hours it takes a couple of turns of the key to catch, runs rough for a few seconds then clears, somedays the cold start is worse than others

    Once the car is started its fine for the day and has no issues whilst driving..

    The car was checked by audi before my ownership for injector issues and according to my paperwork the injectors did not need replacing

    Read it could be tandem pump but at £200-£300 I want to know if it could be anything else before shelling out for a new one

    Cheers
    #1
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  3. heap1000
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    heap1000 Member

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    [Jun 21, 2013]
    I have the same issue but on a 140 bdk. Mine is after it has sat over night, when I start it sometimes the engine shakes that much I think it is going to fall out! The revs jump to 1200 for a second then go back to 820. Turning the key on and off 3 times (not so it starts the engine) to prime the fuel seems to improve the start.
    #2
  4. max69vk
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    max69vk Active Member

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    [Jun 21, 2013]
    Change the filter as a matter of precaution (about £15 for the part), they do go black after a long time & Im willing to guess its never been changed before, once you've done this get your car scanned on VCDS to check the torsion value.

    Ideally on the BKD you want the torsion value to be at 0.5, once this is checked & adjusted ok, manually adjust the rear cam to match the position of the front.

    The fuel filter & rough idle aren't necessarily related but they won't be helping your issue either, + its a fairly common guess to say the tandem pump is failing but without physically removing it you can't actually check the internal seals.

    Do a search for torsion value on this forum & it will bring up a shed load if info.
    #3
  5. SAiLO
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    SAiLO Enthusiast VCDS Map User

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    [Jun 21, 2013]
    My fuel filter was jet black both when I replaced it around this time last year and this year. No cold start problem though. How old is your battery? Does the car smoke when you first start it from cold?
    #4
  6. chinnyhill10
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    chinnyhill10 Member

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    [Jun 21, 2013]
    When my battery was failing the poor starting was actually quite similar to when my lift pump packed up about 6 months previous. In fact my first instinct was "oh no not again". New battery cleared the issue totally even though the old battery passed the test at the local autofactors. I put in a Varta Silver Dynamic and starting was like a different car.
    #5
  7. s3reptdi
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    s3reptdi Member

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    [Jun 21, 2013]
    Checked the glowplugs? I think each one should read 0.3 ohms
    #6

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