Definitive answer please!! :-p

OVRA3

OVRA3

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Hi all,

I've searched the forum and it's conflicting answers.. If you remove your oil cap at idle and the car sounds like it might stall does this indicate a bad pcv or is it normal? Tfsi engine?

Any ideas?
 
dont think it should try and stall, have you scanned it with vcds?
whereabouts in Norwich are you
 
There are no fault codes at all would a faulty pcv show a fault or not?
 
I emailed my vw mechanic his response was.. Breather system is under vacuum from inlet manifold. Taking oil cap off causes leak and weak air mixture... Normal!!! Closed my own thread lol
 
it should be no harder/different to remove the oil cap when its ticking over, to when the engines off.
it should only slightly upset the smoothness of idle when its removed.

if the oil cap feels held down by vacuum, then when removed theres an intake of air thru the oil cap hole and then the engine looks like its trying to run on 2 cylinders/struggling to keep running.

then yes the valve is faulty and subjecting the crankcase to the idle vacuum in the inlet manifold. the air in the crankcase is unmetered air the same as a normal atmospheric air leak would be. and its most certainly a cause of rough idle.

you can get fault codes such as misfire faults, throttle body faults, air leak (mixture adaption) faults. but not always!!
 
the pcv does a balancing act..... stopping the crankcase being SUBJECTED to the VACUUM in the inlet manifold.
while at the same time allowing any CRANKCASE PRESSURE to be DRAWN OFF by the vacuum in the inlet.

thats the difference. and why yours is most likely faulty.

dont forget theres also boost pressure in the inlet under boost conditions, the pcv also isolates the crankcase from this too.
 
the part is only like £40, theres a fitting guide on here, and the part is a redesigned one..... and it takes 15mins.
the hardest part is getting the engine cover/airbox off its rubber mountings......
 
murran said:
the part is only like £40, theres a fitting guide on here, and the part is a redesigned one..... and it takes 15mins.
the hardest part is getting the engine cover/airbox off its rubber mountings......
Click to expand...

Thanks mate do you know what the part number is by chance?
 
Forge catch can fitted to my S3, no more PCV issues as it was nothing but trouble on the old FR not to mention the carbon coked inlet valves.:icon_thumright:

2012-06-20070438.jpg


2012-07-12170846.jpg
 
Last edited:
JamesO said:
http://i1146.photobucket.com/albums/o532/jamesoverton/a99c48a7.mp4
Click to expand...

that looks pretty normal tbh. you didnt seem to struggle at all removing that oil cap?

the ones (5 or 6) ive come across at work you physically could hardly get the cap off due to the vacuum inside. and when i did get the cap off they damned near cut out. yours is just hunting a bit, which is normal.

why are you worried about it if its running normally with no fault codes?

theres a thread somewhere with a guide and part numbers.....
 
Last edited:
murran said:
that looks pretty normal tbh. you didnt seem to struggle at all removing that oil cap?

the ones (5 or 6) ive come across at work you physically couldnt get the cap off due to the vacuum inside.

why are you worried about it if its running normally with no fault codes?

theres a thread somewhere with a guide and part numbers.....
Click to expand...

I didn't think I was worried but it was the lumpy noise I was worried about if you think it's normal then awesome :)
 
if i was a moderator on here (one of the moderators with half a clue about how a car works..... not sandra in other words!) id piece together all the facts from the various threads started on here about this pcv issue and make a decent sticky about it including your video on how the tfsi engine should react when the cap is removed..... to me yours seems fine in that video.

but it maybe intermittently sticking after boosting. does it always tickover aswell as that?

id be a little pro-active in your case and get it into the dealer...... tell them that you think it idles funny sometimes after using full boost/accelaration...... and you think its to do with the pcv valve unit and you know theres a redesigned unit to replace it. and you want it replacing foc. see what they say??
 
It doesn't hunt I think they call it.. I suppose I was worried on the basis that if you put taking off the oil cap into google you get so many conflicting answers normal not normal and I think that's why I was after a definitive answer.. Agree with what you said someone needs to set the record straight.. Thank buddy
 
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