Lack of Punch (boost)

[gavsteryoung]

Guys,

I need your help. I have just had my S4 service at QST. They carried out a pressure test on the engine (im guessing this is to test the troublesome pipes on the intake) well everything was fine. Also Turbo's were fine.

Well, now I have got the car home I have noticed a lack of boost. Before if I floored it the car would really push you in your chair. But now it feels decidedly flat.

The car still runs very smooth, just when I floor it I come to expect the surge!

Is there something this pressure test could have broken (a weak part maybe)

I cant go back to QST as I live 100miles from them.

Any ideas would be appreciated....

[Dippy]

Yes, a pressure test is not a simple procedure so something could have gone wrong.

Surely under the circumstances you have no choice but to go back to QST?

[belgianS4]

Best thing you can do is go back.

Can be a broken or misplaced connection or hose clamp...

Best thing to do is going back to QST my guess.

Grtz

[gavsteryoung]

Ok, I called QST, obviously nothing can be done without taking it there for them too look at. But they suggested I take a look at the diverters.

He also said that car would probably be less perky in the heat!

Anyway took the diverters off and blocked the pipes with a dry cloth. I set about sucking in the bottom hole and both seem completely sealed. This is correct yes? The right one, if look at the engine from the front had a little oil in it.... but I noticed the braided pipe going into the top had frayed and felt very soft compared to the rest of the pipe.

Is the suction that goes through this enough to make the pipe collapse under acceleration.

Sorry to sound dumb, I am, and im only just getting to know how the car works.....

Look forward to your replies.

Regards

Gavin

[Mik]

I had QST test my car for airleaks with their test equipment earlier this year and give all clear....only for me to find airleaks a few weeks later when the car still wasnt running properly - even after they had the car down 3 times.
I would get it checked out at AmD.

Mik

[Morpheous]

The Test Kim carries out would not have damaged your car, all they do is remove the air mass meter and fit an adapter to the intake pipe, remove and block off the breather in the Y pipe and pressurise the intake system with compressed air, and listen for leaks, this is how we used to check the intake system when I worked at Porsche, Audi recommend spraying carb cleaner around the sealing surfaces when the engine is idling, an increase in engine speed indicates a leak.
Both simple but I prefer Kims way. You can here where the leak is from.
Might want to check air mass meter plug is fitted correctly though.
Could be a duff meter, they are proper crap and can now be purchased as an exchange for a shade over £80 odd squid.
You need a 5052 0r vag com to check the MVB, mine now goes upto 200g/sec with a new meter on snap boost.
Fault will show bank 1 bank 2 lean mixture if its bolloxed but not always, a faulty meter can go un noticed as the driver fails to detect the drop off in performance over a long period of time.
A faulty meter on the new stuff won't always bring the check light on, you have to verify the g/sec to tell if its functioning correctly.