I hear an intermittent high pitched whistle/squeal (vacuum leak?) from the engine area. Don't have a clue where its coming from.

I'm thinking its somehow related to very bad gas mileage 10mpg.

Should I just try basic stuff first tuneup and plug change ? Air filter was OK at an oil change last week!

pclaptop



Vacuum whistle and poor gas mileage, 2003 WJ 4.0l

 

Do you have access to a smoke machine?
As an aside, my 01 GC 4.0 has a whistle like sound on cold start for a 1/4 mile or so, almost like a turbo sound-I have no vacuum leaks