This Trooper 2 months ago started a hi pitched squeal in the eng compt. Sounds like vacuum/intake leak. Have checked every vacuumline all intake gaskets finally found if I manually change the pos of the butterfly the squeal stops. Always squeals at idle. If I move the butterfly and it goes into limp mode, Higher idle and reduced power on dash and no squeal. I have cleaned the t-body and replaced base gasket with no change. Butterfly has no rough edges or worn edges that I can see or feel. When driving only squeals at idle. Any thoughts?
Are you using cold air intake?
If not, check the air hose for leaking. Any vacuum noise from throttle body should be dampened by the intake system.
December, 26, 2012 AT 5:02 PM
No cold air, just stock intake and air box. I wondered about the tube and a possible pinhole. I'll check it real close. I've moved the hose around while running and it made no difference. I even unhooked the air box and it made no difference. This squeal is ear piercing. I don't understand the butterfly position affecting it.
December, 27, 2012 AT 2:29 PM
When vacuum is present and causing a wheezing noise, increasing or decreasing the throttle would change the amount of vacuum and this can reduce or eliminate the noise.