High-pitched noise at 1000-1500 RPMs

[lchrzan]

Rather annoying high-pitched whiny noise that happens under these circumstances in my 2003 Vibe AWD:Warmed up, driven at least 5 miles.Only at 1000-1500 RPMs - it stops at normal idle (around 800 RPMs) and it stop when I hit gas. Most noticeable when deccelerating at a light or stop sign.Appears to come from the alternator side of the engine compartment, but it's not the alternator.AC on or off, no difference.Anyone having any similar experiences?Any bulletins about this that I haven't recognized?Thanks for all help!

[JohnC]

Sounded like a vacuum related noise until you said it does not whine at idle rpm. Have you tried listening thru a small diameter hose or sounding bar/stethoscope to pinpoint the location.? I wonder what emmision controls componets change state after warming up and at those rpms? Good luck and let us know.