I have a very high pitch whistle noise coming from (I believe) the back of my engine area. A friend of mine who's a mechanic said it sounded like a vacuum leak. He sprayed carb cleaner around everywhere but we couldn't find anything. He said not to worry about it unless it gets worse. I don't seem to have much of a performance problem, but the noise is a little louder. What should I do? How can the leak (assuming it's a leak) affect my car?

 

Does it increase as RPM increases? If so, then sounds like alternator whine.

 

I think its normal, mine makes a very very slight whine thats noticeable when in the low rpm range such as 1100 to 1800 rpm and its usually heard when picking up from 2nd to 3rd gear on my automatic 6th gen LX. I assume its the the air passing through the throttle body when the valve is opened at the slightest angle to let the least amount of air in as possilbe rather than a big quantity when the gas pedal is engaged more.