Since I bought my last car in August of last year, I haven't driven the Camaro much. It needs a lot of work and I just haven't been able to do anything yet. I drive it once in a while. I can't remember when it started doing this, but probably within a year.

I'm terrible with describing things so I'll do my best here. When I first put the blower on (ATI P600b), the bypass valve would make a normal air noise. At steady high rpms, it would stay open and just vent into atmosphere. No fluttering. If you were in boost and let off the throttle it would flutter like normal, but still making just air noise, like ts ts ts ts ts ts ts very quickly. Now it makes a whistling noise. Still flutters but makes a very different whistle. Also, at steady high rpms, it is fluttering and engine shakes a bit due to it. Then engine isn't missing btw.

I haven't had a chance to look at the bypass valve and vacuum lines yet so I'm hoping that is the cause. Have you guys ever heard of something like this?

 

Do you have a boost/vacuum gauge on the car that you can monitor when this condition is occuring?

 

Yeah, I don't notice a difference compared to before though.