Erratic idle 523i Auto E39

[DuncanThomas]

I hope you can help

My car BMW 523i has not got an erratic idle.




Before I really stick my head under the bonnet I thought I would ask for help

The symptoms are:

When revs drop to idle sometime it nearly stalls or very lumpy 9around 200rpm

This can be rectified (most of the time by blipping the throttle) – not always easy with an automatic

When it happens there seems to be a sucking noise from under inlet manifold (black) under the + point should I be jump starting the car

(sorry not that technical) but always willing to learn and get hands dirty

Other than that it seems to run fine



Any pointers for me when I get my head under the bonnet and what should I look for

Thanks in advance

[M3Nate08]

Sorry man I don't know about that one

[Bimmer M.D.]

Please give more details, and be more specific.

[darkhorse737]

sucking noise you hear is indicative of an intake leak.

look under you hood and check your intake hoses for obvious cracking. In case, you can't see any visible signs, easiest way is to use a can of brake cleaner to aid you in your quest for finding the leak. spray around the intake area - AFM, rubber parts, especially where rubber joins to metal.

while you do that, notice the change in idle while you spray. There will be a marked change in idle the moment the brake cleaner soultion touches the break/crack

[p528I]

Dont know about the sucking sounds but its displaying signs of a dodgy vanos system. Google 'vanos problems' to find out more info