Ok, so I noticed this little issue one night when it was nice and quiet. Every few seconds, I hear a sound that is similar to a long exhale. It's audible while in the car, but barely audible anywhere else. At first I though it was some small creature that got hit and/or caught up in the axle somewhere, but that was free and clear. Has anyone else come across this? What the Hell is it?

 

I can think of 2 things that would build and release pressure... The fuel system and the cooling system. Either one of these might sound like a sort of exhale when purging fuel back into the tank or coolant into the overflow bottle (or coolant into the radiator from the overflow bottle)...

Also the vacuum operated plenum doors will sometimes bleed off vacuum and might sound like that as well. Thats all I can think of

 

could be leak in vacuum system for heater. why it would only do it once in a while is the kicker.

 

Well, I decided to sit in the car for a few minutes to listen to it, and I tried hearing it under the hood with no luck. Sounds like it's definitely coming from the back, so I'm assuming it's the fuel system regulating itself. If anyone else has any suggestions for me to try, I'm all ears

 

test evap system, it may be as easy as gas cap in need of replacing. look at number 8 here https://camaroforums.com/forum/93-02...62/#post557634