I did make another thread earlier this month but the problem persists.
When giving it full throttle, the car sputters around 5000 rpm as if it were bouncing on the rev limiter. When giving it gradual throttle, it doesn't happen. Only when accelerating hard. It's very frustrating this.
I've changed the following. Bank1/sensor1 oxygen sensor. Checked camlobe and cam follower for wear. No wear and cam follower was replaced. Changed the piston in the HPFP to a vis one. The car was fine when all that was changed. I believe the oxygen sensor made the difference. But the problem is back! And this time it seems worse than ever. A mechanic said he graphed the fuel pumps and turbo and they are all running fine. I'm lost for what this could be. He said that he reckons it could be a stretched cam chain but I'm not too sure. It's a lot worse when the engine is hot!!
The car is 290bhp stage 2 with S3 intercooler, downpipe, Vis piston and ramair induction.
Please, if anyone has any idea of what this could be, I would appreciate it greatly if you could let me know.
Many thanks.