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Discussion Starter #1 (Edited)
What’s going on impala family I have a 2003 Impala Ls 3.8... I been having this turbo like whistle for a min now & I could never pin point where exactly it was coming from. If you rev it you can hear it a lil bit but when you drive that’s when you hear it. I cleaned the throttle body before I started hearing this noise btw & while I was cleaning it did kickback on me like a pop or something... Okay now I have a Jmb fender well Intake & and now you can hear it louder. It sound like a lot of air is being released when I press the pedal a lil hard... the intake helped me out a lot because now the hissing sound is coming from under the car the only thing I didn’t check to see where the hissing sound coming from yet that’s causing this noise... Any Ideas? It makes my car clunk when taking off a lot now ever since I put the Jmb fender intake in
 

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So it was not doing this before cleaning the tb? With what you post, it sounds like maybe something is not seated right with the tb or something not tight with the new intake setup and it is drawing unfiltered air from that opening.
 

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Discussion Starter #3
I replaced the throttle body gasket twice that didn’t change anything but when but when you rev car under hood you hear the whistle but not as much but if you sit in car when door open & rev it you can hear it coming from under the car... you can hear the hissing sound ( not the sound from the intake)
 

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Discussion Starter #4
And I do have a coolant leak but not real bad but it drops a lil when running at normal temp it even started raising a lil
 

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What’s going on impala family I have a 2003 Impala Ls 3.8... I been having this turbo like whistle for a min now & I could never pin point where exactly it was coming from. If you rev it you can hear it a lil bit but when you drive that’s when you hear it. I cleaned the throttle body before I started hearing this noise btw & while I was cleaning it did kickback on me like a pop or something... Okay now I have a Jmb fender well Intake & and now you can hear it louder. It sound like a lot of air is being released when I press the pedal a lil hard... the intake helped me out a lot because now the hissing sound is coming from under the car the only thing I didn’t check to see where the hissing sound coming from yet that’s causing this noise... Any Ideas? It makes my car clunk when taking off a lot now ever since I put the Jmb fender intake in

I recall working on my son’s 2004 Grand Prix GT with the non-supercharged 3.8 engine (now gone) - fully stock with no modifications. This was the W-Body, like your Impala.

There was a hard black plastic, curved air tube, which went behind the engine (near the cowl / firewall). I recall it being loose or knocked-off when we did some work on it. It was somewhat centered between the two fenders, at the rear of the engine. The fitting was somewhat sloppy and not tight, and it was easy to dislodge.

Perhaps check there?

Also - are you aware of the PCV valve set-up, under the black, hard plastic fitting? The PCV valve has two different size o-rings, which if not present, would cause an air sucking sound.
 

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Discussion Starter #7
Talking about the curved air tube btw.... I Did the PCV valve with the new o rings and all like 2 weeks ago so I know it isn’t that
 

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Okay thank Now do it have a name?

Working from distant memory - it was some type of fresh air or vacuum tube (may 1/2 inch or less in diameter). It could be seen and reached while standing by the driver (left) side fender, and reaching behind.

I wish I could remember more to help, but I recall the hiss noise when it was dislodged.
 
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