I have a 92 Camaro with a 3.1L V6 MPFI engine (VIN: T) that has a whining/whistling noise. I know it is not the belt, but it sounds like a vacuum like somewhere around the manifold / plenum / throttle body area. I have see previous threads saying it was the throttle body mounting flange gasket so I purchased a gasket set and started to take apart the throttle body and clean it and replace the gasket. The set I got came with a bunch of other gaskets so I took off the plenum and replaced the plenum to manifold gaskets and the throttle body gasket as well. While I had the throttle body off, I decided I was going toean it and the service manual says to remove the IAC valve and TPS sensor before using carb cleaner on it so I did that and snapped off both the bolts for the IAC valve and one of the bolts for the TPS sensor. Luckily I was able to get the rest of the snapped bolt for the TPS out with vice grips and a lot of penatrating fluid. So after that, a new throttle body from the junkyard, and a new gasket the noise if still there. I also blocked off the EGR tube connection on the plenum because my EGR valve was deleted. Please somebody help.

Thanks advance,
Justin

 

I have solved the issue. It was the lower plenum to manifold gasket.