Does your ICV "buzz"?

[colin86325]

Can anybody go out to their car and test whether the idle control valve buzzes or hums when the engine is off but the key is in the Run position? If you can't hear it, test with your hand and see if you feel a vibration.

On my E30 M3 you can hear the ICV buzzing clearly.  But my 318iS does not buzz.  Likewise, on my girlfriend's 318i M42 there is no buzz either.

I'm wondering what is supposed to be normal.

[DesktopDave]

My M42 units buzzed when I tested it with 9VDC...but the one on the motor never did.  I don't recall the M20 units doing that either.

[colin86325]

Thanks Dave, so it did not buzz on the car.  This seems to confirm what I have experienced.  Maybe Motronic 1.7 uses a diffferent control mechanism (like a stepper motor) vs the Motrolic 1.0/1.3?

Anybody else?

[deansweet]

I did the turn the key to on and check for buzzing and neither (91' M42 318i and 318is) of ours do this buzzing you speak of?
We need to find another E30 M3 owner to check?

[colin86325]

Thanks Deansweet!  So we have 5 M42 samples where there is no ICV valve buzz.  I think this confirms for me the proper behavior for the M42 ICV.

For the E30 M3 I'm about 95% sure that it is supposed to buzz.