Help-acceleration problems!!

[ned]

Can any one help.
My Leon 20Vt (W reg)is having problems accelerating. When putting my foot down the turbo kicks in around 3500 revs. It then very quickly dies. There is no acceleration at all and it feels like the engine has stopped working.Then a couple of seconds later,it kicks back in and I am off until I change gear when I then have to go through the same scenario. The car drives fine when driving normally!
What might this problem be as I am worried that it might be something expensive.!

[Magnus_Anderson]

Not sure if this is the same problem but I had a similar problem with my Leon Cupra R. The difference beeing that my turbo would run fine until I turned the engine off, for example filling up with petrol etc. When the car was restarted I had no turbo whats so ever, no acceleration etc. This only happened though when the car had time to warm up if I stopped the car and restarted it whilst it was still cool then I had no problem.... Talking to Mark Sheerin he advised me to pump my accelerator pedal whilst driving and that would 'kick' the turbo back in to life again as it could be a dump valve problem. It worked! Anyway the point I am getting to is that when the car was taken in to the garage to be checked out for this problem it was discovered that it was the Dump Valve was at fault and that it was leaking air when it shouldn't have been. Try taking it to your nearest Seat dealer and get them to check the dump valve (these sort of problems do not turn up on their diagnostics). The problem I guess with you is that you are not under warranty anymore so the garage might charge you for their time :(