Dubie79

Hey guys, got a noise squeal in synch with throttle advancement. When coasting high speed nothing, as soon as I touch throttle squeal noise is back. Had a similar C5 do a similar noise that turned out to be a crack in the intake manifold. Could this be the same??

dadaroo

If sitting still and advancing the throttle makes the noise I would get an auto stethoscope and try to find the source.

Dubie79

. Noise only heard while driving and accelerating....

wcsinx

If it changes with throttle position but not necessarily engine speed, then that is almost certainly a vacuum leak. Check every hose for cracks/pinholes. Replace any that feel stiff.

Sometimes you can track them down with smoke (matches, cigarettes, etc.) I usually just grab things until I feel air moving through my fingers. Vacuum is highest at idle, so you can usually find them without someone playing with the throttle to make the whistle hit a frequency you can hear.