Audi Allroad 2.7T lack of power and hissing noise
 

Hi all,

I have the following issue with my Audi 2.7T.

In last 6 weeks car feels very heavy on take off and there is a hissing noise coming from the engine when I accelerate but I can only hear it with the window is up. I checked the car for boost leaks with the smoke pressure tester and there are no leaks, also there are no error codes on the vag com.
My fan belt needs replacing as it occasionally squeaks.
Could it be the case that the hissing noise is from the fan belt as it only happens when the car is under load and that the lack of power is down to MAF.

Any help and suggestions would be greatly appreciated as I am at the stage where I don't even know where to start now.

Alem

um sounds like turbos going bad how many miles do you have?

I am having the same problem with my 2001 Allroad. I purchased my vehicle with bad turbos, so I have no idea if it had this problem before I replaced the turbos, but I suspect that it did. If your problem has been solved, than I would love to hear what the problem was and if it is not solved than I will let you know when I figure it out. This seems to be a common problem with the 2.7 Allroads, so someone must know the answer. My problem is simply (No Turbo Boost). My turbos are low mileage and very tight. I have no exterior hissing or leakage like you mentioned. I just rechecked both waste gates to make sure they are closed properly, because the car runs like they are continuously open. I replaced the N75 valves twice, with no improvement. Last night while driving at 60 mph, my turbos boosted for about 2 seconds until I backed off on the throttle, and the power boost was enough that I missed my exit. I know that this problem is something simple and I can't wait to have it solved.

My 2002 Audi Allroad (2.7T) had the same problem (lack of power and no turbos). Took to local mechanic and they did the smoke test and found an air leak on the Y Shape intake (it was cracked on the bottom). They replaced the part and all the power came back. They said the car had all kind of unusual codes thrown and luckily the smoke test discovered the air leak. Now back to normal.

Hissing Sound is an air leak have the engine smoke tested or boost leak testing and hunt down the problem could be bad intake pluming a cracked inter cooler blow boost coupler a crack in the intake pipe going from the mass air to the hard plastic Y- tube on the top of the engine. i would boost test it as far up the system as you could right after the mass air would be the best spot.

That's good you know what it is now. Mine gets boost and does good to around 3000 rpm then the boost goes and the car like jerks, and pops then if you keep the fuel going to it and not let up it will regain boost and get moving very fast. Almost like it's to much boost or it floats the valves or something. I've checked diverter valves and wastegate. I'm thinking of replacing all c clamps on the air hoses. Although i don't hear any bad noises like they are loose when on boost. It gets around 3-5 psi before not boosting at all. If it is under load as in more weight in car it does worse. As noticed very easily when trying to pass other cars or going up a hill and maintaining speed.