I got my audi A4 2.8 just few days, still playing with it. It's a little rough on idle, so yesterday, I cleaned throttle body, then found that idle keep revolving about 50-100rpm. Check the Bulletin, yep it's need a TB re-adaptation. I still have a vag-com for my long passed away passat, figure out it'll work on Audi as while. so just follow the procedure from vag-com website. Engine warm, KO-E-Off, no pedal, engine-basic setting-060(yours maybe 098), right on. Adpt run to adpt ok. all green. later I check the procedure, found I turned the controller off right away instead wait 30 sec(actually not necessary). So I tried again. now it's show Adpt error/ no Adpt function. then gave me code:
2 Faults Found:
17967 - Throttle Valve Control part (J338): Fault in basic settings
P1559 - 35-00 - -
17973 - Throttle Actuator (J338): Lower Stop not Reached
P1565 - 35-00 - -
I tried a OBDII scanner, Vag-com, snap-on and launch X431, all just can do nothing. some time these code will set the CEL, but after you tried clear it, codes are still there, but no CEL. Car still run smooth, but lake power and you can never go full throttle. I don't belive the TB gone.
So google, found only one article described the solution, not pretty write up, but works. This procedure will work on many Audi/VW cars
So I use his procedure and explain a little, On A4 it's pain of axx to remove the intake hose adapter to TB, A6 will be no problem at all.
Step1 on 2.8 remove beauty cover, intake flex hose, vacuum plate with 3 10mms and bolt, then disconnect vacuum line(don't brake them, they are quite fragile) and elctronic connector.One 5mm Allen bolt connect intake adapter to tb, You need proper allen key and a small hand to do this. One 2.8 it's not necessary to remove throttle body from intake manifold.
Step2 leave the plug on TB in and remove the 6 torx (think it's torx-10) that hold the protective plastic cover onto the TB and remove the plastic cover.
Step3 the problem lies in the potentiometer. there're two set probe contact to circuit, one for main shaft(controlled by gas pedal), not the problem here, problem is the one under the spring, with drove by a small motor on TB, which will only turn throttle plate in very small angle, I've seen it's only 0.0-0.4 degree, and normally it's park near 0.0(not on 0.0). when you computer initial the TB adapt, the motor will turn back and forward to reach both limit, and computer will read both, I'm not sure it's dirty contact point or loose probe spring, I just don't have time to do further research, but I think, just because computer did not get enough feedback from TB, then either hang it on somewhere or stop working. so be very carefully clean the board and contact point a little and press the probe spring a little to make better contact. and learn how to run two portenttiometer, One by throttle cable, which undernearth TB, we don't need do sth wih it. another by motor, we can turn it by move a white/iovry plastic sector gear wheel, when you monitor it by vag-com measure block(060/098), you can see the angle it changes, this one is what we need. then go next
Step4 hook up vag-com or what every scan tool u ca use, K-On-Engine-Off and go to engine module and set vag com to do a throttle body alignment. I use basic setting and 060/098. if possible bring the laptop to engine compartment for easy operation. When you hit go on computer, tb Motor will run, in good case, it'll back and forth one or several time, and then finished adapt. But when it's problem, it'll stop in certain point and can not finish the setting. So if above press job or cleaning job won't help, let’s go next.
Step5 go back TB. don't force anything, you may brake something, after press go on computer, while motor turning, us a small flat screw driver press the probe to circuit board, and another hand try help motor turn CC direction. And watch the computer, if goes to Adpt Run-Adpt OK. If does, then finish, if not, the motor many stop running, and you'll get one more code, then go back and clean the code, and come back to adpt it again, try few times more, when you hit the sweet point, motor will turn right direction and finish adapt. at this point the fault code will be gone. you need a verify.
Step6 try to read code, if nothing there, the finished, if still there, try clear your fault code it won’t clear yet so do Step 5 again.
Box your car back up and enjoy your now perfect tick over.
You can find some pic in above link, I just lazy to take pics. Good luck and use the guide on your own
Modified by projects at 7:00 PM 1-24-2009