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Phimosis · 07-15-2009, 07:01 PM

I have a similar, completely annoying situation, but my description is different. Let's see if this jives with what others are hearing.

The sound is a high pitch, but not a squeal... Mire like a human voice humming at high pitch. It's not a stereo ground loop, because it's not coming from the speakers. It sounds like it's coming from the engine compartment, left side, maybe around the brake booster. At idle, the sound completely goes away. Above 2500 rpm I can't hear it either, maybe because the engine is making exhaust noise plus the thrashing about from the vvel. The sound is most prominent from 1000-2000 rpm under light load or no load. Driving slowly it's the worst. Once stopped, if you blip the throttle from idle to 2000 rpm you can hear it, but that only lasts for about 30 seconds. I tried trouble shooting it and prolonged idle time made it go away, despite blipping the throttle multiple times.

I thought it might be a vacuum leak, so after letting my car cool down, I thoroughly checked all the rubber hoses and everything seems to be fine. Could it be a vacuum diaphragm humming and that is it's normal functioning state?

I took my car to the dealer before I saw this thread and described what I was hearing. They looked at my car and said nothing was wrong with it.

07-15-2009, 07:01 PM	#9 (permalink)
Phimosis Enthusiast Member Join Date: May 2009 Location: Oildale, CA Posts: 412 Drives: 2013 911 4S Rep Power: 416	I have a similar, completely annoying situation, but my description is different. Let's see if this jives with what others are hearing. The sound is a high pitch, but not a squeal... Mire like a human voice humming at high pitch. It's not a stereo ground loop, because it's not coming from the speakers. It sounds like it's coming from the engine compartment, left side, maybe around the brake booster. At idle, the sound completely goes away. Above 2500 rpm I can't hear it either, maybe because the engine is making exhaust noise plus the thrashing about from the vvel. The sound is most prominent from 1000-2000 rpm under light load or no load. Driving slowly it's the worst. Once stopped, if you blip the throttle from idle to 2000 rpm you can hear it, but that only lasts for about 30 seconds. I tried trouble shooting it and prolonged idle time made it go away, despite blipping the throttle multiple times. I thought it might be a vacuum leak, so after letting my car cool down, I thoroughly checked all the rubber hoses and everything seems to be fine. Could it be a vacuum diaphragm humming and that is it's normal functioning state? I took my car to the dealer before I saw this thread and described what I was hearing. They looked at my car and said nothing was wrong with it.