SubzeroX

it randomly occurs, and when it does it stays for about a minute then goes away..
can occur once a day or a couple times, at different times/hours. Never hear it in the freeway cause engine's too loud so who knows if it's occuring or not.

you hear it a little when i gas it but it sounds the highest when i let off the gas.


sounds like a turbo blow off haha


anyone know what it is or what causes it?? thanks! i am completely CLUELESS


the sound I'm talking about is heard most clearly as my foot gets off the gas pedal (as the RPMs are spooling down)

Hurdigurdiman

Sounds like a healthy engine to my ears.....

Van

Sounds like a rattle to me... perhaps a heat shield on the exhaust loose?

philooo

you have something loose somewhere, certainly a bolt getting loose and a washer playing in the middle. could come from anywhere but check the exhaust line first, plenty of bolts there that could come loose and create a noise that would change with RPM. strange that you don't have it all the time though..

speed rII

Sound's like a intake leak. If you mean that "scoooohh" sound after you lift the throttle?

trapperdog

Timing chain lash maybe. (Tensioner or IMSB?)

SubzeroX

yes the sound as soon as i lift the throttle, that winding down sound

Macster

Put me down in the sounds normal camp too.

However, noises are hard to diagnose even at the car. Have you had a professional tech give a listen?

Sincerely,

Macster.

seanmcr6

air leak gets my vote

try standing next to the engine and listening while someone else revs....you'll get much closer to the source

SubzeroX

i'll have my indy look/listen when i go in for oil change in a week

i'll keep u updated. but do u guys actually hear the winding down whoooosh?

Macster

Hope I'm right but I hear nothing out of the ordinary. There could be a whooshing sound, but I do not hear it.

Have to point out the engine's running at some high(er) rpm, then the throttle is closed.

This creates a big vacuum (well, low pressure) in the intake system, from the TB and its butterfly valve on.

This low pressure -- part of it anyhow -- is used to help remove air from the crankcase.

The crankcase might have some higher pressure due to the engine running at higher speeds, from blow-by and coupled with higher pressure in the intake system, which can approach atmospheric under WOT conditions.

Thus the whoosh sound could be the sound of crankcase air 'whooshing' through the AOS, which is plastic, sits up on the engine and could radiate/emit the noise you report hearing.

Also, the whoosh could be hydraulic power steering fluid coursing through the hoses.

Be safe, though, and let an expert listen to the noise.

Sincerely,

Macster.

SubzeroX

thanks so much

Pac996

After turning up the volume I could hear that semi rattle or chain clacking noise on letting off the throttle. Wouldn't hurt to take the air cleaner off and survey on top plus check under the car like was mentioned for heat shield being loose. Just something to do while the engine is cold with lots of everything in there to finger around with and wrench a little to see if there is something loose.

I'm also thinking it's reflected noises off concrete and walls playing games since you possibly wouldn't hear the noise on the road.

Barn996

It sounded normal to my ears as well, you guys are starting to make me paranoid...

Hurdigurdiman

Its defo the IMS going to explode hahaha. Only kiddin. I must admit I am always listening to my engine as well and imagining things. Very rareley do I drive with the radio on. I had the top down the other day and God forbid I was travelling next to an unseen railway line with good carraiges moving slowly. I was consentrating on the road with an ear open on the engine sound and an eye on the dials when this train must have pulled to a halt and the goods wagons clanged together and I almost **** myself. "For frankfurters sake" I thought to myself. I thought my engine had fallen out. hehehe

You might be as well asking an indy for a second opinion as some of us can't hear anything wrong. We probably could if we were stood behind the car with the lid opened. Anyway hope all turns out well for you.