95 540i, will not idle when cold... stumped! Please Help!
 

Help!

I have cleaned the idle control valve... and it checks out with the VOM and does "buzz" when the car is running....

When cold it idles to low and wants to die..... after 15-20 min the idle is fine and everything is good...

however once warm if I am running the AC and sit at idle for an extended period (i.e. traffic), the idle drops again and the check engine light comes on....

I tried to pull a code with my carsoft program, but it is not setting one.....

Anybody have any ideas????

ask here
http://www.bimmerboard.com/forums/e34/

It's a bit of a job to replace, but chances are, based on your description, your PCV valve is the issue. It is actually the entire back cap of the intake manifold and the easy way to replace it is to remove the intake. I just did 2 of these this week on newer 740iL's that came in with the same issues as what you are describing. This is becoming a more common problem as the mileage numbers climb on the V8 cars. There is a rubber membrane inside the housing that either tears or disintegrates and when it does the intake is able to suck directly from the crankcase. Quick check is to unscrew the oil fill cap with the motor running. If there is vacuum at the cap as you unscrew it, the PCV valve is bad. Check it out... good luck...

BMWmech1

I have the same issue with my 97 540i

Finally....
 

Ok, so finally today, the idle went to crap in a place where I could stop and check to see if I am getting a vacuum at the oil filler..... and yes big time....

So I will order the part and replace it.... hopefully finally this will do the trick!