Background- M44, 79k miles, DASC since 59k miles

Sent blower out for rebuild, received back, re-installed and everything ran good for close to 800miles. Then...


CEL- 2 codes (Idle Speed Actuator - Open, and another Closed)

No way to hold rpms anywhere between 800 and 2200. Just kiss the throttle at idle and the revs JUMP.

Car may stall when coming to a stop. Clutch in, and it's like the car doesn't know where to stop RPMS, they fall almost to nothing then sputter back up to idle.


FI guys and Z3 group have offered some guidance but I'm still not 100%

Oh I've i've also replaced all clamps/hoses as well as

pressure regulator valve
idle control valve
throttle valve switch

And in between shifts you get a "put pop" sound from the exhaust

It sure sounds like a vacuum leak, but based on the fault codes I say to check for ground and voltage at the idle air valve connector. It's also a good idea to check the crankcase vent valve. I'm assuming it runs good except for the poor idle. Otherwise check cylinder compression.

It sure sounds like a vacuum leak, but based on the fault codes I say to check for ground and voltage at the idle air valve connector. It's also a good idea to check the crankcase vent valve. I'm assuming it runs good except for the poor idle. Otherwise check cylinder compression.

After initial re-install of supercharger there were 2 vacuum leaks which have since been fixed and the car ran great for 800 miles or so. Crankcase vent valve was replaced, I guess I could have a bad gasket between the manifold and the head.....that would suck.

However when I had vacuum leaks they created a rough idle, but did not limit the rpms at which I could hold the car. The fact that I can't hold rpms steady anywhere between 800-2200 makes me think it could be something else.