Erratic Idle

[Rhyso]

lol dammit! Just realised I REALLY shouldnt have said that l

not with me around anyways 

[Teutonic_Tamer]

I can't get the picture onto the computer as I don't have a scanner sorry. The pressure control valve which they talk about is 100% definatly the PCV valve which is also the positive crankcase ventilation valve  . It clearly shows the the PCV being the black plastic 'strip' which is held onto the rocker cover? under the engine cover by self tapping screws. I changed this part myself so I know the part. My engine code is an AXX as it's early.

As per the VW bulletin, the problem seems to be a failing non return valve in the PCV valve itself. Maybe this is the pressure control valve, so effectively a PCV  inside the PCV valve? 

I think you are spot on.  This PCV valve has three separate valves inside it, including the large disc-type diaphragm valve.  I havn't had chance to check yet, but something in this assembly must be operated by pressure generated from the turbo, because as mentioned earlier, a crankcase can never run on a vacuum - unless someone has hidden a fookin gert Dyson inside the engine! 

The part I fitted has the part number 06F129101L. I can possibly get the part number of the part that was replaced tomorrow, depending on wether or not it is still in the garage, or binned!

OK, the last time I looked at mine (cleaned the innards), I noted the part number as '06F 129 101 F' - so they have obviously updated it.  Thanks for sharing.

[sambo]

The PCV valve has NOTHING to do with turbo boost!    It is ONLY the DV which is affected by turbo boost, unless you have modified your engine to work on the two stroke cycle!

So are we doing a bit of a U turn in opinion T_T? Not saying i'm right, your wrong or anything childish, but your opinion towards the way this component operates seems to have changed. 

Genuinely interested to hear of  exactly how this works as it has raised heated discussions on 2 forums now and most people just like to know about the facts.

Cheers, Sam

[Teutonic_Tamer]

The PCV valve has NOTHING to do with turbo boost!    It is ONLY the DV which is affected by turbo boost, unless you have modified your engine to work on the two stroke cycle!

So are we doing a bit of a U turn in opinion T_T?

Not at all.  The actual 'boost' is still controled by the divert valve or recirc valve (or what ever VW are calling it this month).

And until I can actually have a real nosey, I'm gonna sit on the fence.  Though I do now accept that it seems as though the PCV is plumbed in to react to the turbo boost.

And I categorically will not be changed by the bollox in that yankie engine guide - because anyone who is anyone regarding engines, will vhermently tell you that crankcases NEVER work on a vacuum.  Just like the oil pump is NOT driven from the camshaft, as it claims.

Not saying i'm right, your wrong or anything childish, but your opinion towards the way this component operates seems to have changed.

I certainly don't have any 'hangup' about changing my opinion.  But I do need to work on engineering facts.  Because I'm sure we all need no reminding that the Yanks systematically come out with BS . . . .

Genuinely interested to hear of  exactly how this works as it has raised heated discussions on 2 forums now and most people just like to know about the facts.

Huh, TWO forums?  Linky please. 

[sambo]

Don't think you need a link to the other forum, your in it!  re: catch can's and there purpose/use. Admittidly it is a slightly differant discussion but it involves the same component.

Like what has been said earlier, your knowledge is very valuble to forums like this. It is not a matter of who is right or who got it wrong. My input to this topic was based on info I had picked up from having a similar problem and trying to find an answer. I am by no means experienced enough to be able to comment on technical details, just come to a conclusion using the various drib's and drabs of info out there on the net and available to me via a friend who is a master tech at Vdub.

Hopefully we/you can find a definative answer to this failing PCV valve issue (which VW have tried to combat with this updated part) and find the best solution to the problem it causes. This may just be fitting said updated part, or the use of a catch can or something completely differant.   

Presumably the PCV valve only allows deposit's to build up on the valve stems etc if it has failed? Or is there a fundimental issue with the design (current or updated version) which allows this process to take place? If the later then I can understand why people are looking at using a catch can set up.

I may be seeing my VW mate later tonight anyway, so will ask for his opinion on the matter if I remember! 

[ukdub]

I believe its the one way valve in the 'front' PCV that fails and leaks boost pass it.  The signs of this is a slight loss in boost and oil being blown out of your oil filler cap due to boost pressure not being stopped by the one way/non return valve.  The crankcase vents through the 'front' PCV and 'rear' PCV when no boost is present and only the 'rear' PCV when there is.  I am sure it is more complicated than that but you get the basic idea.  This is the reason I have had my catch can on for over a year now was to remove altogether the 'front' PCV and therefore not having to worry about the failing one way/non return valve.

Technically the crankcase still vents out of the 'front' but through the catchcan then back into the PCV system for the 'rear' PCV to deal with.  So now the PCV system is not directly connected to the inlet manifold.

I stand to be corrected though.

Oh and the catchcan has the added benefit of LESS deposits on the valve stems.  Whether the fsi engine needs it, that is still under discussion,  but certainly doesn't make it any worse.