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PCV Test

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by Scott.T, Oct 30, 2012.

  1. Scott.T

    Scott.T Well-Known Member

    Oct 7, 2012
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    As some my know I am trying to track down a light missifre at approx 2,000rpm.
    I have just read about the PCV being a common failure and that a sympton is breather air being sucked into the intake in during vacum, which is where it would be during light throttle/2,000rpm

    A test for this seems to be attempting to remove the oil filler cap to see if it runs rough or has suction.

    When I initially viewed the car I took the oil filler cap off to check for contaminants/head gasket failure while it was running and the car imediately stalled.
    Would this indicate a PCV issue ?

    #1 Scott.T, Oct 30, 2012
    Last edited: Oct 30, 2012
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  3. twist123

    twist123 Member

    Jun 7, 2009
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    Symptoms to check, oil around filler and coil packs. Take inlet manifold pipe off on manifold side and blow through it, if its blocked thats good if air flows freely its knackered. If theres vacuum at the oil filler while motors running thats fine. Lift dipstick halfway, if theres a suction sound coming from the "puck" of the PCV its fine.

    This is in my experience, I just replaced mine for no reason before discovering all this! Doh!
  4. Pabs

    Pabs Active Member

    Jun 2, 2010
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    Had the same problem on my b6 1.8t 190, check the crankcase breather valve they are known to go and only cost a few ££££, the symptoms are rough idle ( sounds like a subaru, bob bob bob bob bob), stalling when you take filler cap off, changed mine and it cured the rough idle straight away and now purrs like it should do...

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