I thought I'd post up my experience to help others who might be suffering from this same problem.

I recently purchased an 06 A4 Avant S-line with the 2.0t, and shortly after getiing it home, I started having intermittent problems with a check engine code that I was told was related to the intake manifold runner, and really only effected emissions. I had been dealing with a VW shop, as I don't live near an Audi dealer, and was told that they did not have the proper equipment to reflash my ECU, which they claimed may not be up to date.

Shortly after getting it back from the shop I started to notice a slight (and sometimes severe) hesitation at wide open throttle everywhere above 4500 rpms. The problem was also intermittent, and seemed to be getting worse. The car was acting as though it was running too rich, and I wondered if the previous owner had maybe gotten an aftermarket ECU tune, that was not up to snuff. After all, the car feels more powerful than a large 200hp car should.

I had been checking all the forums, and none of the solutions seemed to fix the problem. I tried resetting the driving history, I changed the plugs, and coil packs, but no deal. I was still getting the occasional check engine code, but the problem persisted even when the code did not.

Finally, my wife and I were in Vancouver for our anniversary, and decided to drop the car off at Capilano Audi. They managed to sort out the problem quickly. It turns out there is a flap in the air intake that is controlled by a motor that reacts to a calculation based on throttle position, rpms, load, etc. This motor was malfunctioning, and therefore not opening fully under WOT. They replaced it, and the hesitation is gone. They made sure the ECU tune was up to date, and it was. I guess 200 horsepower feels faster if they're German. (do they use clydesdales or what?)

Anyways, I'm just glad to have the car running properly. It was the second best anniversary present I've gotten...

 

Cool, thanks for the info and congrats. What was your first best anniversary present?

 

Uh... something my wife gave me.

 

That is because of the torque!