4LinkS4

I have a stock 2000 S4, and recently it doesn't feel as strong as it used to. Occasionally second gear is a little late the with surging power like it used to.
Is there a way to check to see if my turbos are boosting properly? I dont have boost guage. Could BP valves be the answer? Should i invest in some aftermarket ones. Thanks.

NewYorkS4

on mine, power just seems inconsistent. there sometimes, not there others.

Could always be a torn TBB as well.

Shredster

This could very well be the problem and by all means, be the first thing you check (stock TBB or not).

DSCI4

took it in for my 32k service and told them it felt like it was hesitating and surging. the dealer said that both BPVs were failing to hold vacuum and they replaced both of them. car feels MUCH better now.

my only worry is what this may have done to the turbos....

4LinkS4

How would I check to see if this was the problem?

4LinkS4

Thanks i will mention it when i take it in for its 25K service. What could it have done to the turbos if it was the BPV's?

Andy Hedin

There is a detailed write-up in the Tech Section of AudiWorld.

DSCI4

if the BPVs are failing to hold the boost then the turbos are going to have to work harder to make the requested boost. so in a way it's like running with a chip (makes the turbos work harder) and according to Audi that will kill your turbos.

also, when we did the blown turbo poll awhile back it seemed like boost leaks (TBB, BPVs, f-hose,....) was a common condition prior to turbo melt down.

we'll see....

s4bi4 X5

Get some Samco hoses, I had the same problem

dpd

could be loose charge pressure hose clamps,vacuum leaks,air leaks,old style injectors,bad maf[or one on way out],faulty by-pass valves.if a by-pass valve is going bad or bad,you should hear a loud hissing noise in front of the motor and you might even hear one vibrating.new style injectors have pink tops[old style is gray].would need more info to help better