Sponsored by The Tire Rack

[bmac27]

Just returned from a quick stint around town tonight - didn't run the car extremely hard but did a few quick 3-4 second pulls in between stoplights towards the end. Upon parking in my garage I noticed a generator-type sound coming from the rear right side of the car, and as I got closer it was definitely coming from the wheel well area. It almost sounded as if it was coming from within the tire itself. The sound occurred with the car off, and lasted about 90 seconds, and was only in the right rear wheel. There was a small "hiss" sound right as it stopped. I hopped back in the car quickly and didn't start up but toggled into the TPM system to check and make sure nothing was wrong, and everything showed green. Could this be the TPM system measuring tire pressure post drive? I honestly don't know much about the system at all, and had always figured it was a pressure measuring tool for while the car was in use, vs. standstill and off. I have the standard RFs and am positive I didn't clip any sort of pothole/debris in the road but may have snagged a lose screw or nail someplace. Appreciate any thoughts on what this is/could be

[1QuikWS6]

TPMS system does not make any noise - it's basically a small module connected to the tire valve stem with a pressure transducer that reads pressure & sends an RF signal to the receiver (small black box contained in wheelwell area)

By 'right hand side' do you mean the rear driver side?

If it is the rear passenger side - could be the Evap System that includes a pump and charcoal filter (although I have never heard a noise coming from that either).

http://www.realoem.com/bmw/showparts...19&hg=16&fg=10

Can't be the fuel pump as it should shut down as soon as car is turned off, runs quiet, & it normally holds the line pressure and does not release. Unless there is something wrong with the pump...

The hissing sound might be explained several ways - but coupled with a 'generator type' noise for 90s is somewhat of a mystery. The fact that you hear ANYTHING like you explained after the car is off tends to make me think something is up, as I don't hear any noises after my car is off.

[bmac27]

Originally Posted by 1QuikWS6

TPMS system does not make any noise - it's basically a small module connected to the tire valve stem with a pressure transducer that reads pressure & sends an RF signal to the receiver (small black box contained in wheelwell area)

By 'right hand side' do you mean the rear driver side?

If it is the rear passenger side - could be the Evap System that includes a pump and charcoal filter (although I have never heard a noise coming from that either).

http://www.realoem.com/bmw/showparts.do?model=WC33&mospid=49567&btnr= 16_0619&hg=16&fg=10

Can't be the fuel pump as it should shut down as soon as car is turned off, runs quiet, & it normally holds the line pressure and does not release. Unless there is something wrong with the pump...

The hissing sound might be explained several ways - but coupled with a 'generator type' noise for 90s is somewhat of a mystery. The fact that you hear ANYTHING like you explained after the car is off tends to make me think something is up, as I don't hear any noises after my car is off.

Sorry should have been more specific, it was the rear passenger side of the vehicle. I'm used to noise in the cabin upon shutting off the car as the navi and electronics do their thing but this was totally new. Hopeful that this is not impending hpfp fun

[ChasVS]

Originally Posted by 1QuikWS6

If it is the rear passenger side - could be the Evap System that includes a pump and charcoal filter..

[bmac27]

Appreciate the help, did a little more searching at work this morning and found these threads helpful. Sounds like its the system checking for leaks and is normal

http://www.e90post.com/forums/showthread.php?t=53175

http://www.e90post.com/forums/showthread.php?t=458990

[gunnerxq]

It's normal I have it on the left side.