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Nottin' like boost...
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i hear a hissing noise at idle, i looked at the vacuum line that goes to the boost controller and that looks fine considering its a new silicone line, and i looked at the boost gauge line, both dont seem to be making the noise but i still hear a hissing sound

the weird thing is though as soon as i give it some gas it goes away, also when i have the ac on and the car revs itself up it also goes away

during the hissing sound my vacuum is like 11 which is quite low to what i am use to but when it revs up a little and the noise stops it gets to about 15

what can this be?
 

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I have a Pontiac Firebird 3.8L and I have the same exact problem. I hear a hissing noise when at idle once the car heats up and once I shift into gear, the hissing goes away. I have seen threads suggesting its a bad throttle body, but thats all I can help you out with im not too tech savvy. The noise is a high pitched steady whistle that I have grown accustomed to. Since it goes away I dont worry too much about it.
 

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Take some throttle body cleaner and spray some in the area of the hissing. If the rpm's change when you spray in a specific spot thats the area of the vacuum leak.
 

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You're aware that you just bumped a 7 year old thread about a Supra to talk about your Firebird on a Supra-based Forum, right?

The F-body forums would most likely be your best source of info for what you need.
 

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I have a Pontiac Firebird 3.8L and I have the same exact problem. I hear a hissing noise when at idle once the car heats up and once I shift into gear, the hissing goes away. I have seen threads suggesting its a bad throttle body, but thats all I can help you out with im not too tech savvy. The noise is a high pitched steady whistle that I have grown accustomed to. Since it goes away I dont worry too much about it.
its the 3.8, all firebirds sound like that.....
 
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