Another Strange Noise

[fairleymac]

Hey guys, I've got a strange noise that seems to be happening completely at random. Idle, or in the first few gears (cant hear it anymore by 4th or 5th due to engine/road noise).

It sounds an awful lot like a quiet turbo blow-off valve. Generally just sounds like pressure release of some sort. It seems to be happening more often in colder weather (now that the mornings are cold again I notice it almost every day). I've never been able to be at the dealership when the noise is happening, I think because it will stop once the car is fully warmed up.

This is NOT the standard "ticking" noise that your dealers will tell you is normal (I won't comment in whether it is or not), I've heard that noise on other 3's and this is very, VERY different.

Any ideas or suggestions?


Car info:
'07 Sedan GT, MT, approx 25,000 km.

[agm_ultimatex]

Well cold air gives the engine more power, as its denser, so I wonder if maybe it going through the throttle body you hear it time to time. Is it similar to a BOV in the fact you hear it when shifting/lift off gas? Also, do you have a CAI? Ive heard that some CAI's almost have a supercharger similar whine to it.

[dkwan416]

Hey, I'm hearing this as well on my brand new 3, and it sounds like it's coming from the front passenger side am I right? sounds like the release of pressurized air (actually, I personally think it sounds like it's sucking IN air) and it really does sound a little like a BOV. I suspected it was the intake, but the intake manifold is on the driver side of the engine bay.

[sas]

I heard strange noise even on switched off cold engine.
I hope it veapor in conditioner. Wath else it could be?