I just took my car out of winter storage. Replaced the plugs, changed the oil, and the O2 sensor. When I got on the highway and hit boost the car stuttered a little. While checking this out in the garage while idling the engine I felt air coming out of the air relief pipe that runs along the Y-pipe and connects to the air filter. Does this mean my ACV or Air pump are going bad?

 

The relief pipe is similar to the BOV for the turbos, but for the airpump. It does push excess air out so the airpump isn't overworked. That part of the system doesn't really have much of an effect on the turbo operation.

 

Thanks Mahjik.

I figured out what the problem was!!! Stuttering occurred at about 4000-5000 rpms. After searching the forum other members who had the same problem reset their ECU. I did the same and my problem is solved! No more stuttering. It must have gone into some kind of limp mode.