babins4

I have just had a full system and panel filter fitted to my 1999 S4 which has realy improved the throttle response and low down power. I have a problem with it holding boost the diverter valves have been pressure tested and all appears ok. Some times it boosts well but alot of the time it seems to fade out between 3500rpm and 5500rpm? It also sounds as if it has a dump valve to atmosphere from the n/s of the engine bay, i have checked the hoses and the all appear in good condition but it only seems the whoosh under load when changing gear and not when it is simply revved up standing still (only under load)? It is booked in for a remap in 2 weeks but intend to at least find the issue before it goes into the garage! I will fit Samco hoses throughout eventually but the labour cost for the job is more than the parts and dont fancy taking the front end off the car in my front garden?! Help me out guys any suggestions?? Also boost gauge in the centre air vent has any one fitted one and how easy/long does it take. Cheers.

jaimesonlee

That strange and sounds like it could be a PITA to diagnose. Here is what I would recommend; since it only vents under load, either put in on jackstands or on a lift and have a buddy go through a couple gears while you are observing under the hood. Remember though since the car is off the ground the gears will run very quickly so have the person inside be cautious of this.

Although you say the DV's passed a leak test I would still pressure test the whole system anyways. It's easy to do and if you don't have one, they are cheap. you can get one here

http://www.awe-tuning.com/pages/shar...ssure%20tester

If you decide to get one and do it just make sure you unplug the PCV valve and securely cap off tube on the Y pipe that it disconnected from and open the oil cap.

This is all the advice I can offer but I hope it was somewhat helpful.

Good luck with the problem.