Car revving in idle

[Rocknrolla84]

Hi,

My golf has just started revving itself when in idle to about 1500 rpm then a few seconds later drops back down to normal tick over, I've heard it maybe the crankcase breather valve however I'm not sure and don't want the dealership having my eyes out like normal.  Any help would be massively appreciated

[bacillus]

Checked for a vacuum leak?

[mattchaps]

Have been looking into this myself. Do you get a hesitation when accelerating as well? Does your idle change when you pull the dipstick out?

Sounds like the PCV valve or "Positive Crankcase ventiliation" valve.

[Kiwi]

Also check your DV, as it maybe split, and this causes the same issue.

[Rocknrolla84]

Is it likely to be an expensive job? As I'm having my cam-belt and water pump change next week would it be worth getting them to have a look at it as I've heard of mk5 gti's being recalled for this problem in the past

[Boothy]

I recently had a fault fixed and then developed a very similar issue to this. I took off the engine cover and found a breather pipe from the PCV completely off so if I were you I'd be having a looksy mate. Could be a cheap fix. I also had an air leak on the pipe running into the throttle body so maybe check that too?

[h4rdy]

PCV or G247 or both.

Get a BSH PCV deletion kit from Dubtek on here for £70 delivered and never have the problem again!

There is a way to check yourself but if your not mechanically minded, don't bother.

[Rocknrolla84]

Happy days, I'm not mechanically minded at all!!! So I think I'll be seeking professional help on this one, however thanks for the tips and I'll have a look to see if anything is visually loose, thanks again!!!

[h4rdy]

There is a way of temporarily blocking the outlet from the PCV to the inlet manifold to test the PCV.

If you want to try it I can talk you through it but I have to warn you I have no idea if it is frowned upon on here or not.

I would also get it VAG COM'd this will give you a better idea.

[Rocknrolla84]

Yeah I've got my mate doing it tomorrow so should defo get an answer 

[h4rdy]

It will probably say 'air leak in fuel system' or 'lean/rich at idle'.

Let me know if you want a quick PCV diagnosis.