I have a whistle coming from the cab of my truck that is definatly not audio related. It is really noticeable and goes away when the gas pedal is pressed. It is becoming really annoying and I would like to know what it could be. Thanks.

 

Check the large circular gasket where the air intake tube connects to the throttle body...those have been known to rot away and cause whistling sounds at certain engine rpms.

 

Yeah it's not that because I replaced it about 2 years ago and I looked at it and its fine. It sounds like it is coming from somewhere in the passenger side of the dash.

 

Only other thing I can think of would be the vent hose that runs from the air tube to the valve cover on the passenger side. When I first bought my truck, mine was split...wasn't causing any sounds yet but I fixed it anyway.

 

Hmm. This is very weird.

 

It's a vacuum leak somewhere. You say it's inside the cab, check all the vacuum lines in the cab for a split. Try the different vent positions to see if all are working OK, might help narrow it down. Goes away when you step on the gas because manifold vacuum drops then.

 

Okay, I will start checking around. My dad said that's what it could be also.

 

And my truck has a power issue. Especially in OD. Could fixing the possible vacuum leak fix my power issue? I have heard that vacuum can do some weird things.

 

It won't hurt in any event. Have you fixed your plenum yet?

 

No. I don't think it is bad because I looked in the intake and there wasn't any oil or anything dirt related. It was as clean as a whistle. And I have done a couple tests on it such as spraying PB Blaster and smoking the whole intake and the rest of the motor and lines and the only thing that had smoke come out of it was the air box.