i just got this 2000 audi s4 and heard thay where pretty fast stock well mines not i knew somthing is wrong i hooked a boost gauge up to it and when i floor it, it jumps to about 8 or 9 psi then drops to about 5 then slowly loses more psi . and this is when im flooring the whole time..??? what with that?

 

Sounds like a boost leak to me. You should be peaking around 12 and sustaining around 9 psi. If your sustaining 5psi, your car may be running in safe mode. First I would check the throttle body boot. They have a tendoncy to tear. It's pretty easy to remove, and you can find diy fixes for it on this forum.

 

agree on where to look for boost leak and thats probably the problem, but mine never spiked at 12, it always hit right at 7-8psi and held..

OP, whats your boost/vacuum at idle?? just let us know if your car is running good BESIDES when its in boost...

 

I'm actually in the same boat as well. Mine has great pickup at low RPM then about 4K it just drops off. I'm trying to figure that out right now. Is your check engine light on?

 

Def do a leak test first. What I did when I got my s4 a year ago is replace the things that commonly leak: turbo hoses and DV's.

 

the vac on the boost gauge is about 20 at idl

 

I just made a pressure test kit from this site and hooked it up to realize there was a large tear in the throttle body boot (big surprise). I just replaced it and now it rips!!