I have an 02 A6 Quatrro with 4.2L with 155,000. I had an irritating front knocking noise when I would turr, drive over uneven surfaces, or hit speed bumps. I inspected and noticed the control arms and tie-rod ends had play. I replaced all those things and still had knocking. I discovered the steering rack 10mm bolt under the battery was way loose. I tightened that and the knocking is gone. My problem now is when I drive I have a lot of swaying going on. When I am driving anywhere from 20mph-70mph and turn slightly the ESP engages thus causing the car to sporadically brake and stall. All good things if the roads were slick but its 100 degrees here in Arkansas so that is not the case.
I had a new set of Cooper tires put on yesterday as well as the four wheel alignment done. That helped a little, but the ESP problem and swaying persists. I called Audi to see if something with the electronic steering needed reset and they said no. I did notice when the Audi is up on the rack the front wheels both turn inward pretty drastically. When the weight is back on the car they go straight. Not sure if that is normal or part of my problem (or the problem). I feel like when weight is shifting around in driving the wheels may be turning in a bit causing the problem. There is nothing loose though when the weight is off the car or on the car. I am leaving tomorrow on a road trip and would really enjoy and much more stable ride. Any help and ideas appreciated!