[jakuum]

So I took my car out for a late night drive since she's been sitting parked for about 4 days now. Also wanted to take care of a low tire issue. Drove the car about 20 miles mostly freeway so it was warmed up when I got back.

When I got back and turned on the car power (but not the engine) to power the air compressor I noticed a buzzing sound coming from the engine bay. It sounded like either an electrical buzzing or a high pitched fan. If I took the key out of the ignition it went away after about 5 seconds, and then if I turned on the car's electrics again it came back. This is the vid I took:

Now, when I turn the car on and it idles I don't hear the buzzing. Instead it's replaced by a rather loud rattling sound that sounds like it's coming the OFHG area which was recently replaced along with the VANOS recall work. First video is with the engine bay open, and the other closed:

Any idea what the sounds could be? I've never heard them before coming out of my car and a search doesn't turn up anything similar. At least not that I an find :/. Only engine/exhaust mods that I've done are the PPK, PE, and Cobb charge pipe.

[e36addict]

I see you're located in DFW.. Car still under warranty? Interested in bringing it over to BMW of Dallas? Shoot me a PM.

[SUPAN]

Ratting is wastegate? Normal

Buzzing is the pressure convertor.

[jakuum]

Originally Posted by SUPAN

Ratting is wastegate? Normal

Buzzing is the pressure convertor.

Hrm, I thought this was an issue with the N54 motor and not the N55? This is the first time I've heard the noise and I've had the car on with me outside of it several times before in the past couple of months (CP charge install, PE exhaust install, speaker install to make sure they all work) and had not heard the rattling before.

Is the pressure sensor only activated with the electrics on and motor off? And is it activated every time the car's electrics are turned on?

I went out this morning to replicate the noises after warming the engine up (also listened to the car after a cold start at idle) and the buzzing noise was no longer present but the rattling still was. It could hear it a lot more though after the engine had been warmed up.

[ashmostro]

Buzzing could be HID transformer. Do you have xenon headlamps?

[SUPAN]

Originally Posted by jakuum

Hrm, I thought this was an issue with the N54 motor and not the N55? This is the first time I've heard the noise and I've had the car on with me outside of it several times before in the past couple of months (CP charge install, PE exhaust install, speaker install to make sure they all work) and had not heard the rattling before.

Is the pressure sensor only activated with the electrics on and motor off? And is it activated every time the car's electrics are turned on?

I went out this morning to replicate the noises after warming the engine up (also listened to the car after a cold start at idle) and the buzzing noise was no longer present but the rattling still was. It could hear it a lot more though after the engine had been warmed up.

Buzzing sound is on and off ...

On idling, try rev hard a few times ... i guarantee u the buzz will come back and it is irriating ...

complain twice at dealership and they change the pressire convertor and all goes well .... reckon i got it at 50k km

rattling is the wastegate ... if you want new dme the sound goes softer but shitty car performance.

your choice noisy vs performance ?

[jakuum]

So an update. The noises ended up stopping on their own so I didn't take it in to the dealership. Really odd but hopefully they don't reappear. Or if they do they are consistently reproducible.