Hi Gents, I'm new to this forum and have only just returned to VAG ownership after 5 years or so.
Basically I have recently bought a 2001 Audi S3, it was advertised with approx 300bhp and a hybrid turbo, the guy I bought it from didn't know much about it but it pulls well, everything seemed in order and he had a lot of receipts including one for the turbo from CR turbos for the hybrid and extensive work from a company called Quick Motorsport.
So as I said everything is running well boosting to 1.5 bar and still holding 1.0 - 1.1 bar at the redline but thought I would check everything over and today was the first chance I had to have a good poke around under the bonnet....
First thing I noticed is it has a turbo tip fitted and the tube that the N75 valve is supposed to be connected to has a bung in it and the N75 is just cable tied up. Second thing is that the N75 has manual boost controller type thing attached to it (only the bottom of the three connections was connected on the MBC so can't believe it was actually doing anything)
So I thought I would remove the MBC and install the N75 on to the tip as it should be... I took it out for a drive and now the boost seems out of control (I was careful on the throttle and it quickly boosted beyond 1.6 - 1.7 bar so backed off immediately). I am now running it with the N75 disconnected which gives me 5psi as I'm now concerned I have no idea what map this thing is running and if its fuelling properly etc.
Anyone got any ideas?? Is this a faulty N75 ..? What would be the correct way to install a MBC and do most people just use purely the standard N75 boost control ?