BMW Blog

Hello,

I just bought a used 2000 328ci with 63,000k. I've had it for like 3 weeks, and now I don't know what the h*** is up. Problems:

1. The car makes a hissing/squealing noise with light throttle. It sounds like a brake squeal. I think it's a air leak or something somewhere. It more so just annoying than anything. I had it checked out and they couldn't find anything wrong with it. Vacuum Leak?

2. The check engine light is now on and my car is idling roughly on occasion and will stall during idle sometimes. It sometimes feels that there's no low end power and will stall off the line. Also, sometimes it takes few cranks for the engine to get going. For my first 3 weeks with the car it started faster than any car I've ever owned. I think it may just be an o2 sensor, not sure though.

3. The car makes a sound in 1st gear when you get going. Not sure if it's normal (if someone could verify that would be great). But, it sounds like a blow off valve or something. A Psssst. It makes the sound the second the fuel gauge meter jumps up. Also, do your cars' fuel gauge slowly raise even with little gas, or does it just kick up after gassing it for like 3-4 seconds? Fuel pump problem?

So I'm not sure if all this could be related somehow. Any help or tips would be very beneficial. I need to buy a Bentley manual and a Fault Reader, but I'd like some insight. Please help!

Thanks!

Sound like it's ALL related to a vacuum leak to me. It's odd that they couldn't find anything, though. If the check engine light is on, scanning for codes would be a good place to start.

Hello Bungy,

I think you're right with the vacuum leak. Just today my car got worse, stalling and idling roughly. I popped the hood and heard a loud hissing sound coming from around the intake. I had my friend give it some gas and the sound is very noticeable when giving throttle (like a blow off valve and squealing) I tried to look around for a loose hose but couldn't track it down myself.

For now, the car is just parked and my mechanic friend is going to look at it tomorrow (the BMW dealer is booked up for the week) as I'm not as experienced greatly at repairing cars. I'll keep you updated.

Thanks!

Problem turned out to be a bad camshaft sensor. Costed me about $200CAD to fix it. 100 for the part and 100 for inspection and work to replace it. Now the idling is back to normal, no more CEL, and no more stalling.

But now, did I ever have a vacuum leak. When I pop the hood, I can still hear a significant hissing. Is that just a regular intake sound, or should that be closer to inaudible when just idling? I guess I should take a can of brake cleaner and spray it around to confirm.

Also, when I just start going, still in first gear, I still hear that whoosh sound, pretty quiet but still there. And when cruising in 3rd or 4th I still hear a high pitched whinning noise that only happens with light throttle. Anybody know what this could be?

Thanks,
Alex

hey man..dont worry about the hissing..if you have an intake, that's what it is..I have a Dinan CAI, and when I first start up my car, it makes a slight hissing sound until it warms up..and at any gear, I lightly gas it, it hisses at light throttle...it is no biggie.....glad to see you go your other issues fixed..

there is a crank case oil air seperator found under the manifold (p.c.v. valve) if the diaphram is torn it will create a wistle noise. pull off your oil cap with the engine running and see if there is a noticeable change in sound. if it is really bad it kind of sounds like you are strangling a duck every time the idle dips or surges. with the intake kits on the cars the vacume changes and makes it a little more pronounced. some noise is normal but if it is making the idle fluctuate you may need to replace the valve and the plastic hoses that attach to the valve because they will break when you remove them. some times if the car is cold and you come off a higher rpm than idle the car may have a noticeable dip in the idle rpm. hope that helps ...