Has anybody solved the whistling Jeep problem? My 01 4.0 GC whistles at me while driving when I release the throttle. Under acceleration its quiet. It's annoying as hell.

I wouldn't mind it so much if I could teach it a tune!

 

Sounds possible that its air passing by the throttle plate. Its just a guess, I have heard this kind of thing before. It usually seems worse with modified air boxes, CAI's and throttle body spacers. Might also try cleaning the throttle body. Im sure you have eliminated the possibility of a vacuum leak.

 

yes, no vacuum leaks, even tried an unlit propane torch at idle. Car is completely stock with no mods. I'll try cleaning out the throttle body and see what happens.