Recently my 2.7 has been having boosting issues. At slightly hard acceleration I'm barely holding 0psi. If I really step on it I can hit 4-5psi at around 4k rpm for a second while it begins to lose boost really fast. Shifting has also become rough. Also the rpms increase a lot slower than usual, and at WOT at 4500rpm the rpm needle will stutter, go down a bit, and then go back up. For testing purposes I disconnected the wastegate line from the n75 before starting her up. Once I started it up and began to drive things felt very different. Rpms shot right up at lighter acceleration and shifting was a lot smoother. The one thing I did notice was that boost was a lot more constant and holding all the way through. I made sure not too drive to hard so I wouldn’t mess anything up. Now here is the interesting part. After the drive, I pulled into my garage with the engine running, connected the wastegate to n75 again and went for another test drive. Things felt really smooth and boost was holding strong at 5-6psi around 3000rpm. If I really punched it I would get 10-11psi. I can clear up the problem by driving around the block with the n75 disconnected from the wastegate and then connecting it again. But after a couple of days of driving it will gradually the problem will come back. Does anybody have any idea what could be going on? I'm thinking maybe carbon build up on the wastegate actuator, or the n75 valve. I would really appreciate it if someone could give some input. I'm not quite ready to head to the shop just yet.

 

Anybody?