2000 E46 330ci - bouncing revs, vacuum leak?

[Aceface]

Heyup guys
I think I might have an air/vacuum leak somewhere but can't find it... Have taken off the intake pipe and air box and had a good poke around the the small pipe that looks like bellows under the DISA but can't see anything wrong with them...
The symptom is, the revs bounce when at idle but it only seems to happen when parking of stop/start driving. for example, if i'm edging forwards or backwards, when put the clutch down the engine will rev on it's own a couple of times before settling, somethime it nearly stalls when the rev fall again. Does this sound like a leak somewhere and is there an easy way to find it?
Thanks

[StK]

Sounds like it could be a sensor fault too

[Paddy2bsure]

I think this might be an Idle Control Valve issue. Apart from the ICV itself, it plugs into a rubber grommet which can perish / split over time.

It's not a big job to remove the ICV, clean it out, maybe even replace the rubber grommet 11611437453.

Link to realoem page: http://www.realoem.com/bmw/showparts...79&hg=11&fg=40

[Aceface]

cheers for the ideas, I've got no fault codes stored so I don't think it's a sensor, will take a look at the icv.
cheers

[Paddy2bsure]

Any update on this?

[Aceface]

yep, I replaced the elbow pipe into the throttle body and the little gray one that comes out of the icv and I cleaned the icv too and it's definitely reduced the rev bouncing issues but not sure if it's gone completely, will have to monitor it.

[Dev]

Hi mate, I had a similar problem when i first bought my car. The revs would be hunting up and down. Do a little test...with the engine on and just idling pull the dip-stick out and look out for a loud gasp like sound (like when you switch a hoover off) this is what was happening to mine so I changed a breather on the back of the block at the top which looks like a hockey puck. it cost £26 to buy from euro.

[topboy8384]

hi ya i have same problem ,, how much would this cost at a garage to get dne is the ivc hard to get and his breather hard to get to ?? cheers

[Paddy2bsure]

Have a read of this DIY I've done relating to vacuum leaks: http://www.bimmerforums.co.uk/forum/...-leaks-t40634/

[Paddy2bsure]

Just to revive this thread a little! Vacuum leaks are (in my opinion) the no.1 cause of bouncing revs. I just swapped my DISA for a spare one I had lying around, and no more bouncing revs. The newer DISA is a lot quieter too, not as much whooshing noise from it. The ICV made a difference, but it got progressively worse again.
I still have to look at my injectors, I also have some spares lying about that I may swap in there. Will be interesting to see the condition of the O-rings on each injector, as they can also leak.
HTH