I have a 2000 audi a4 with a t3/t4 on it full exhaust and tuned on GIAC. Everything was running fin then all of a sudden wouldn't make boost. Shut it off and waited 30 min started making boost again but dropped from 15 pounds to 10 and sounds like the turbo is just whining not blowing off either. Could it be a cracked exhaust housing on the turbo? Any more ideas?

 

I would imagine so, but is your dv upgraded? Maybe it's dying either way or the wastegate actuator is jammed or sticking...?

 

No the dv is replaced when the front mount was done with a new blow off valve. Checked the wastegate and it appears to be working right except for opens fully at 2500rpm is that right?

 

How do you have a blowoff valve with a stock dv? If you use a blowoff it would replace the dv (which isn't a good idea on an Audi - at most, a hybrid valve that vents part and recirculates most should be ok).