My 2005 G35 has recently been making a whining sound, its very faint, but it's there... its very slight even at idle, you can hear it inside the car when its dead quiet and no stereo or anything.

RPM's control the whine. It happens with both the clutch pedal IN and OUT so i don't think its the transmission. So in turn it happens both in gear and out of gear.

 

When I see the words "Whining" I think of drive belts, when was the last time you replaced or even checked these? The sound of a worn belt would also increase with RPMs, so that fits and it's unaffected by your clutch....Gary

 

Can you pinpoint the whine?

I've heard of whines coming from belts, intakes, and even through the sound system from an improper ground...

 

Could be a bearing in the alternator or power-steering pump, or possibly an idler pulley bearing that is on its way out.

Best bet is to get an automotive stethoscope and start poking around under the hood while it's idling and touching stationary parts that are within close proximity to what you suspect may be making the noise. You should be able to hear it pretty clearly if it's a pulley or the belt-driven components.

 

i just replaced my belts not to long ago.. but i do notice the sound did start happening after i hooked up my AMP.. so it might actually be from the stereo, because you can DEF hear it inside vs. outside... gonna try turning my stereo off today and seeing if that helps.

 

The reason I suspect your system is because back when I had my system in my Trans Am, I would hear this whine that would increase in frequency with the speed of the motor. I went crazy trying to figure out where it was coming from. Finally, when I was wandering around underneath the car, I happened to bump up against the door panel and realized it was coming from the speaker.

Turns out my Alpine amp I had hooked up to the door speakers had a weak ground. Cleaned the contacts, and I was good to go.