I have a 2002 F-150 and lately I've been getting a whistle in the engine bay somewhere.
I've tried to find it but I can't seem to track it down.
So I WD-40ed all the pullys and it still comes and goes.
It's louder when I let up on the gas and seems to be quieter when I step on the gas when I'm driving.
Anybody ever have this noise?
BTW, it seems to happen more when it's cold outside.

 

when you letup on the gas, the manifold vacuum is greatest.. When you step on the gas, the vacuum is reduced.. Is the whistle a vacuum leak ? Any abnormal operation or code ?

 

I'll have to let you know tomorrow. I'll put the code reader in in the morning.
No performance issues though.

 

I researched this when I had the same issue a long time ago.
PCV and the expensive motorcraft OEM-bend house fixed mine.

 

Rslvstr,
What is expensive?
How much was the part and can I do it myself?
Thanks for your reply,
Murf

 

Sorry, I meant rsylvstr.

 

Expensive for a bent hose.

Get the motorcraft PCV valve and the PCV hose.