[formal]

Having recently acquired a 540i Touring I am trying to track down an air leak on the intake.


The symptoms are :

Misfire - very noticeable around 1200 RPM +

If I stab the throttle whilst the car is idling - it almost stalls before picking up

Very obvious sucking noise which appears to come from under the inlet manifold on top of the engine



Car has 122000 miles - new short engine at 41000


I realise this could be quite a tricky problem to trace - just wanted to see if there were any common failures to check first.


Any thoughts?

 

[Ronnie]

These parts can be prime candidates.

http://www.realoem.com/bmw/showparts.do?model=HE62&mospid=47384&btnr=11_1291&hg=11&fg=15

3, 7, 8. http://www.realoem.com/bmw/showparts.do?model=HE62&mospid=47384&btnr=11_1498&hg=11&fg=40

 

[formal]

Thanks Ronnie,


Does the vent pipe run under the intake manifold?

Unless that non return valve on the seperator has failed it looks like I will have to pull the inlet manifold off to find the problem.

 

[Ronnie]

The vent pipe does yes. :thumbsup

Have you tried spraying some carb cleaner carefully around the pipes and joints and seeing if the engine note changes?