My wife's 2006 2.5L new beetle convertible started to idle erratic yesterday. The car would almost stall then idle up to 1500rpm then almost stall. It only happened when sitting still at idle. Drive-ability at speed and acceleration felt flat but it was still driving. On the first day there was no engine error code but this morning I managed to pull two.
The codes were
P2279- Intake air leak detected
P0507- Idle speed faster than normal
After some troubleshooting tonight I managed to nail the problem to a ripped diaphram inside a psuedo PCV valve on the front of the valve cover. The part is called the pressure regulator valve for crankshaft housing ventilation. The down side is that I can't seem to buy it separate from buying a complete valve cover. A new valve cover is $136 plus shipping. Check out the rubber piece that's causing all the headaches.
FYI, I could hear this thing leak and could feel air sucking in the little hole in the bottom of the outer cover of the valve. I had the classic air leak symptoms where I couldn't pull the oil cap off with the engine running. When I shut the motor off I could still hear it suck air in for about 5 seconds through the faulty diaphram.
Hope this helps others that might suffer from this problem. The car is just over 3 years old with 62k miles. I can't believe this rubber part might end up costing $150???
I'm experiencing the exact same issue, same codes, symptoms and I found the rubber gasket to have a similar tear.
Did you ever figure out if this really was the cause and did you have to replace the entire valve cover??? I have the valve cover off but I also separated the pieces in question just in case I'm able to find the part numbers for them. Let me know how your problem turned out, I need the car running again if I wanna get my balls back from my wife
EDIT: just fixed the problem. For future reference, in case anyone else runs into this problem, the entire valve cover has to be replaced because the rubber diaphragm cannot be purchased separately
Last edited by flip2jetta; 06-06-2010 at 11:14 PM.
I googled the same trouble codes and ended up at this thread and indeed the diaphragm was torn on my wife's 2005.5 2.5L jetta. HOWEVER, instead of buying a new valvecover from VW for $225 I ended up getting a Dorman Solutions kit 917-064 which is a new diaphragm, spring and cover kit.
Simply bust the old diaphragm cover off (so as not to damage the tangs on the VC) and install the Dorman kit. Make sure it's lined up correctly before you snap it on since you get one shot. Otherwise you'll end up busting this cover off too and have to hold it on with a large hose clamp till you can order a replacement.
It took a while to "seat" itself (probably because the dorman spring is twice as strong as the VW spring) but it fixed the problem for under $20.
Sorry for the zombie thread but VW not selling the diaphragm separate is a complete rip off.
Parts geek now sells just the diaphragm and spring to fix this . 19.95 .if you can not get your oil cap off while the car is running. And it revs up on its own at an idle this is what you need. And it's super easy to change. Remove the engine cover. Look for the round cap on the valve cover. Use a small flat screwdriver to pry the round cap off. There is your ripped diaphragm .replace and put engine cover back on. Worked great on my 2005 Jetta 2.5. Quick and cheap.