rough idling and gunk on dipstick housing

[SuperChimps]

Hi all,
Aside from the exciting plans to get a downpipe fitted in the next few days, I've noticed something a bit more worrying. The car (2008 polo gti, 72k) has started idling rough at the lights. It'll give a bit of a shudder and then drop the revs down.

Did a bit of googling and I think it might be the PCV valve? There is also an oily residue on the back of the yellow dipstick housing, which I'd never noticed as pronounced before.

Anyone have any more info or suggestions or recommend a good VW mechanic? (Brisbane north side)

[louis19]

Someone here might be able to give you more info before needing to head to a mechanic, might be something you can sort out yourself but worst case scenario I'd recommend "Prestige and Performance" in Coorparoo.

Theyre workshop is clean enough you could eat off the floor, they're European specialist and pricing is very fair
They're workmanship is also great.

[SuperChimps]

Cheers Louis. Might wait and see what I get here then give them a call. I've read the PCV is a fairly straight forward replace... but people's ideas of straight forward sometimes vary! Plus would like know exactly what it is

[h100vw]

Cheers Louis. Might wait and see what I get here then give them a call. I've read the PCV is a fairly straight forward replace... but people's ideas of straight forward sometimes vary! Plus would like know exactly what it is

Send me or post a decent picture Jack. I have some PCV bits at home.

Gavin

[sambb]

Superchimps - if changing the PCV fixes your problem let us know. I've been chasing that very same idle issue for ages and was beginning to think the PCV could be it. You can be the guinea pig!

[seangti]

On the subaru's (early 2000 models), you could diagnose a dying PCV by driving in a high gear at way too low revs - e.g coming to a stop in 5th gear at 20kph. The car would jerk, kick and buck if the valve wasn't working. If it worked, the car would stall out or try to stall without the lunging feel. Never tried this on a VW and some things work differently on the VW's so may be a sure comparison.

[SuperChimps]

Thanks Sean.gti - I might give that a go. I also found some threads around the place talking about feeling for suction from the oil filler or dipstick if you try and open them at idle (Rough idle).

Anyway, n the process of taking some pictures for Gavin, I discovered my PCV the hoses going in and out are totally covered in gunk - probably years worth. So Gavin's sensible suggestion was just to clean it up and keep an eye on it for the next few days - which is exactly what i'll do. I also found a couple of articles on general PCV workings - this one has a few ideas for checking methods, so I might give them a go too Positive Crankcase Ventilation (PCV)

Still going to go ahead with the downpipe tomorrow.. hopefully it doesn't make things worse.

[sambb]

What happened mate. Did sorting the PCV issue help with the idle stumble?

[SuperChimps]

I dunno, I've been slack with it - gave it a bit of degreaser, and have kept an eye on it. But with work and family stuff I haven't had a chance to do much else yet. This weekend I will try and actually pull it out and have a proper look at it. The day after cleaning it the problem seemed to go away but it has come back again just today. There's a bit of fresh oil on it now, but nothing crazy.

I'm no expert by any means - oil changes are about the extent of my abilities, but hopefully I can see if there's anything drastically wrong when I get in there properly

[SuperChimps]

Had a go at it on Sunday, but my weak hands couldn't wrestle some of the bigger spring clips off. I'm going to get a bigger pair of pliers and have another go.

But while I was at it, someone suggested I look for vacuum leaks by spraying some carb cleaner around my hose fittings and check for changes in idle. So not knowing exactly what I was doing I tried basically spraying every hose fitting. When I sprayed where the crankcase breather hose elbows down onto the metal piping (away from the airbox side) I got a big change. Is that a significant leak? Could that be the cause of the idling issue?