I had a problem with my S3 at the end of last year, intermittently it would go into soft limp mode and only boost to 4 PSI, it got worse and worse until the times it did boost it wouldn't hold at all. At the weekend I replaced the N75 valve - the old one fell apart when I removed it so it was definitely the problem. Now the car holds boost but only boosts to 10 PSI. When I bought the car it would boost to at least 15 PSI. I can't remember the exact figure as it was that long ago I started having problems, but it was boosting to 15 PSI while I was having the intermittent issues with it.
The car is a 1999 210bhp model and the previous owner said he had a 240bhp map done. What is standard boost on this model? 12 PSI?
Has anyone had similar problems?