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Thread: MK5 Jetta error codes: P2279 P2187 & P1093

  1. #11
    Join Date
    Apr 2006
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    VW Race HQ - Sydney
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    Quote Originally Posted by Maverick View Post
    I'd say it's the PCV valve for sure then. You could loosen the cap when the engine is off and open it after you start it up and you should be able to feel air being sucked into the engine. Pulling the dipstick out a bit will also help with removing the oil cap when the engine is idling.

    Here's a good explanation of how the system works

    "PCV stands for Positive crankcase venitilation. There is pressure in the crankcase if you open the cap you now have created the path of least resistance and you will get pressure coming out of the 1.5" hole vs the .5" hole that is the PCV.

    With a PCV system like ours routed back to the intake the point is that whether the vacuum the turbo creates at part and wot or the vacuum is created by the intake manifold at idle it will see vacuum however not too much vacuum. Having too much vacuum will actually literally suck oil right out of the crankcase which is actually more common then the other way with boost blowing into the crankcase.

    If you look at that round flat part of the front PCV portion that is a restrictor, at WOT the path to it is closed by a check valve near the connection for the hose going to the intake manifold this prevents boost from blowing into the crankcase defeating the purpose of the PCV.

    The opposite though when the car is at idle or under vacuum in the intake manifold at part throttle the rubber diaphram in the restrictor pulls itself more and more closed. The higher the vacuum the less flow. So if you have the car running and attempt to open the cap but cannot due to the strenght of the vacuum or the car stalls out because having the cap open is drawing in that much unmetered air then you know that restrictor failed, quite common for the rubber to tear.

    Now if you have so much pressure that the cap blows off or is blowing oil out then you probably have the failed part of the valve that is supposed to seal shut with boost. Oddly this seal works better with more boost (like a DV) and isn't usually increased boost that kills it. STock your car can make 20+psi but is requesting 12 so if it has a leak of say 2psi it can make 14-15 to make the boost it wants, people just don't notice that it fails until their software that is supposed to make 20psi only makes 15 because the leak is greater then what the car can compensate for."

    source: VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com - View Single Post - Pressure under oil cap?

    This is the biggest B/S Ive ever read on how the Crankcase ventilation works on the TFSI .
    Seriously Maverick , I cant beleive you posted this and expected it to be believed !
    When I get more time I'll write up how it all works , there isnt even a mention of the rocker cover which itself has restrictors that work with the crankcase ventilation .
    Bug_racer supports the rebellion of the euro revolution

  2. #12
    Join Date
    Jan 2008
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    Brisbane
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    3,553

    Quote Originally Posted by Bug_racer View Post
    I need an explanation of how this has anything to do with the PCV system ?
    I was responding to whiteVR6's claim that a turbo cannot create a vacuum.

    Hang on , your saying that its possible to have a vacuum on the outlet and inlet side of the turbo at the same time ?
    If there is a vacuum on the inlet side of the turbo and the turbo is not creating boost (engine idling) it stands to reason that there will be a vacuum on the outlet side.

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