im assuming it might be my Blow off Valve, but sometimes (not all the time), when i dont have my foot on the gas (either decelerating or sometimes at idle) this whistling noise is coming from the engine bay

and for christs sake i dont mean the actual blow off valve whoosh, i mean a whistle ...

its the only thing in the engine that i would assume could make a whistle noise, unless maybe a vaccum cap has cracked and for some reason can make a whistle noise??

it wont whistle while idling at home (that would make things too easy), it will only do it while driving (SOMETIMES it does it at idle, but vary rarely)

has anyone else ever had a whistling blow off valve, or had anything under the hood make a whistle noise while your foot isnt on the gas????

 

check all the vacume or air taps on the intake upstream of the turbo. Sometimes air taps on the intake pipe will whistle kinda like when you blow on the top of a bottle. Just wiggle any of them a bit or pull them out or in some. See if that makes it go away.

I had a nissan that did that because one of the hoses from the intake pipe would whisle like a bottle.

 

Check for exhaust leaks too.

 

how would that effect anything?

 

bump

 

Still have the ACV on the car? The internal ports, being as small as they are, can whistle when one of the solenoids "kicks in" during different engine conditions. I think it's my split air solenoid port that whistles a bit on mine...

 

anything with air flowing thru it could do that. it is probably npot the blow off valve, as that is a large pipe and would cause your car not to run if it popped loose. check all your rubber lines for cracks, dry rotting, and loose hoses. if you dont easily find something, get a can of starting fluid, and spray it around the engine bay at idle when the car is COLD. (starting fluid+ hot exhaust=bad) look for a place where it causes the car to idle up when you spray it. once you find that place, look around for a vac leak.

pat

 

also check tension on belts and their condition.

 

its not the belts, as its not a squeeling like a loose or bad belt ... its a for sure whistle ...

and yeah ... i bet its an old shitty vac cap or something ....

i know i got a vac leak or two, they have just never whistled before

damnit

 

I say vacuum leak. My truck did the same thing that you are talking aboutuntil I found a cracked lineand replaced it.