Weird sound coming from engine when getting window up

[95Mx3GS]

I have power windows and just recently I noticed that when I press the button to get the windows up and I am not driving (just parked in neutral and car is running) the engine begins to make a low growl like sound that it usually makes when on the verge of stalling. I even tried testing this out with the windows closed and pressing the up button but it still made the same sound. I am a little worried.


Please tell me what this is!

[Mad Cow]

Your alternator or IAC (Idle air control) could be bad. Do you get a check engine or low battery light when it happens?

[95Mx3GS]

I do not get an engine check light, And I recently got my alternator replaced with a new regular duty one, and all my air sensors and such have been checked and fixed this summer due to a previous different problem.
I am getting worried that this could be a problem as I am getting subs put in this weekend and I am afraid the battery will die very quick.

[Mad Cow]

It's not an air sensor or anything, it's a little valve in the TB that controls the idle speed.

[95Mx3GS]

Oh, okay thanks, and how much would this approximately cost to fix?

And also, its funny that you mention idle speed because since the first day i bought the mx3 the rpm's in idle when starting the car would be from 1500-2000 then would go down to 1000 after a couple of mins. I dont know if this is relevant or not.

[Mad Cow]

That's normal, it idles high when it's cold. But I don't know how much one costs.