At random points of acceelration in my 323, I will hear a ringing noise that comes from the from left of the car. It seems that if I push harder on the gas while the noise is occuring, the noise will go away. The noise never happens during coasting or braking, definitley during acceleration. It could be coming from the tire well area, im not sure what control arms do, or what their symptoms are...also, when I brake at low speeds, I get some type of a rubbing noise coming from my left rear tire well. That brake also squeals. None of these noises are noticible if I have the radio at "average 16 year-old" levels. Any ideas would be greatly appreciated.

the ringing noise could maybe possibly be a synchro..my friends i-roc used to make a squeelling noise when he accelerated as well.......the brake noise might be from the rear pads wearing down???.......but im no bmw tech so dont take my words for golden lol

a syncro? Is that expensive?

I have no idea other than some sort of loose part that is vibrating at a certain frequency. I doubt that it's a synchro. That would be internal to the transmission, and yes, it would be expensive. Does it shift smoothly? The synchros synchronize the speed of the various parts of the transmission/clutch.

I have no idea other than some sort of loose part that is vibrating at a certain frequency. I doubt that it's a synchro. That would be internal to the transmission, and yes, it would be expensive. Does it shift smoothly? The synchros synchronize the speed of the various parts of the transmission/clutch.
I read about syncros, and it seemed more like they delt with downshifting. It dosent seem like an engine part, because it is only on acceleration. Is there some hose going from some throttle thing that could have a leak? And yes, shifts are smooth...sometimes there is a little *clunk* when shifting from 1st to 2nd though....

First, www.howstuffworks.com (http://www.howstuffworks.com) is fantastic for providing pretty detailed descriptions of how things like synchros etc... basically work. As far as your issue, is it a ringing, like a vibration, or is it a whistle type noise? A loose vacuum line could definitely have a whistling or hissing noise. it would most likely be very strong at idle or closed throttle however, as that is when there is the greatest manifold vacuum. Open throttle (which I would assume while accelerating) would minimize vacuum. I wouldn't worry about a little clunk. You'd know if there were an issue. Check ever thing you can where you think the noise is coming from. It can be very hard to find noises like that.

Ok...It is a whistling noise, not a rattling. No noise at idle, but it seems to be at early acceleration to the gear. Not just going from 0-20. It makes this noise in all gears. If I push harder on the pedal when I am accelerating and the nosie is occuring, It will go away. Hope this helps

do you have a cold air intake?

Left side near footwell on acceleration? The fuel filter is around there and would be used when you're on the gas. I don't know about a "ringing noise" though.

No, i dont have a CAI, I bought it used, and I havent put one in...there is kind of a whooshing noise sometimes though, but it might just be air going over the car. And yes, it is on the left side near the footwell. I hear it louder if I have my window rolled down too.

Hope this helps.

Things to look at:

1) Aftermarket glass? If your windshield has been replaced and not properly installed...this can happen. My mother has a corolla...they replaced the glass and ever since, the wind whistle is awful.

2) Brakes dragging...I would jack it up, pull the left side calipers and caliper mounting brackets and clean everything, then reinstall with some anti squeal applied properly.

3) Put the car on a lift and rev it up in gear...this will tell you if the noise is wind/speed related or a drivetrain/brakes issue.

Old thread revival...I had an older friend who working on his engineering degree, and he thought it was my air intake system. I assume it is stock...does this sound reasonable? If it is, what might cause my system to make this noise? Torn filter, leak between sealing, low oil on filter? What do you think?

pphilo9,

I've been asking similar questions.

So far, I've come up with

Air intake boot has a hole in it or a crack.

Vaccum leak ( which I doubt )

The obvious thing to do is to bring it to the shop and have it checked to be

sure it's not something serious.

Just because you don't trip a code, doesn't mean all is well.

Let us know what you find.

There is plenty of info on the forum about this whistling noise.

It is very common with the E46 it seems.

So yours is doing this? How much would a torn intake boot be?

My 330xi has the same issue. I don't think it's anything engine or tranny related. It sounds more like an electrical piercing sound, and it only occurs at half throttle. It drives me mad if I don't have the radio on.

It ended up being a torn intake boot FWIW

It ended up being a torn intake boot FWIW

Thanks for giving us the update.

Mine is doing the same thing. I have a K & N intake though. So it was the boot between the TB and the engine? What is the best way to remove it as I can't even see it very well.

The boots are after the intake, after the MAF, before the Idle Control Valve (ICV) and the throttle. If you replace them, it's also a good time to clean the throttle and ICV.

Here are some useful links:
http://forums.bimmerforums.com/forum/showthread.php?t=693261 (scroll down to Post #14) (http://forums.bimmerforums.com/forum/showthread.php?t=693261)
http://forums.bimmerforums.com/forum/showthread.php?t=900798