First let let me introduce myself, My name is Jake Koenig and its awesome to meet you all.

I have a 2000 Audi S4 that I am the third owner of. It has 100,000 on the clock. I just had the timing belt done and added new HyperBoost DV's. The car has a chip but I am not sure what one as it was installed by the first owner. I also have installed a K&N and Denso IK22 plugs as suggested by Neuspeed.

The Problem
The car pulls well pre boost at full throttle, but somewhere around 4000rpm the car just stops accelerating like there is a huge vaccume leak. If I feathre the throttlte I can get it to pull through however if full throttle (or anywhere near fullthrottle position) it will drop power until it falls to around the four grand mark.

Any suggestions? thoughts? or concerns? Please, as this is the first turbo car I have ever worked on, or owned my thought proccess may be a little different.

Thank you,
Jake

you need to narrow the possible causes by deductive reasoning.

did you notice it at all before the timing belt being done...?

was the timing belt and the DV done at the same time...?

your not getting any ESP or MIL lights when this happens....?

have you checked the fault memory...?

i would steer away from vacuum leak cause, well when your boosting... there is no vacuum. there is positive pressure

to me, if you noticed it when you got it back after getting the DV installed. I'd say there is a problem w/ the DV and to take it back and complain.

vacuum leak would mean boost leak when going full throttle like that

Noticed a surging that occured durring down shifts
Timing Belt was done
Noticed full throttle problem
Associated them with a bad DV
Surging issue was resolved
I replaced the DV's, all hoses and fittings
Still had the full throttle problem
I dont have any lights or other problems

Thanks for the input, keep it coming,

Jake

I disconected the battery over night and the problem is no more.

glad to hear you got it fixed. thanks for posting the solution in case others have the same problem in the future.