RPM stays at 3000 during idle....why?

[BMWZ4ANDE30]

I recently had my a/c repair because it was not cold. After the repair, the RPM started to stay at 3000 even though the car is idle and neutral (and foot not on the gas pedal) at the stop light. it would go from 3000 to 2700, and rev up to 3000 again, and then slowly go back down to 0, the process takes about 15 seconds. it almost feels like the car is possessed by ghost, just revving by itself. anyone had this problem before???

[RobertK]

Sounds like a big vaccum leak or possibly a bad AFM.

Is your CEL flashing?

[BMWZ4ANDE30]

do you think that is relating to the a/c repair?

[HST]

Could be if they damaged a vacume hose when they serviced it. Along with the AFM it could be a idle control valve.

[BMWZ4ANDE30]

what is AFM?

[HST]

AFM = Air flow meter
The big box thingy between your air fliter and the throtle body.

[BMWZ4ANDE30]

which part are you referring on this picture?

[HST]

none.

Part #1 here

http://www.realoem.com/bmw/showparts.do?model=1413&mospid=47322&btnr=13_0597&hg=13&fg=15

[brewerbrandon]

You ever resolve this problem? Im having the same problem with my 1984 318i.

[selturk]

Mine is stuck at 2500 and it works randomly. I'm thinking SI batteries.