Since day one I had noticed that the starter motor never felt as strong as the S6. By the second or third turn the starter motor seemed to loose strenght.
Also, at the beginning of March I did not drive the car for a week, and I only just managed to get the car started.
Every time that either the VAZ computer or a laptop with the VAG.com program was connected to the car's port, the same fault would always come up:
Terminal 30: battery disconnected
or/and
Low voltage.
At times the car would give excellent performance, whereas other time it was quite dissapointing.
Lately, at times, the RS6 would not rev past 6200 rpm in first, Tip or sport, or 6000 rpm in D.
Also lately I could not go over 230 km/h (143 mph) in either 4th or 5th.
Not being entirely confident that my Audi dealer would find the fault quickly, I went to our local Audi tuner, Chip-Logic.
They went out of their way to help me out and eventually found the fault in matter of hours.
One of the main power cables in the main positive power distribution box was loose......(If I remember properly it's near the DME/ECU box)
They also fully recharged the battery.
Since then, about a week ago, the starter motor feels much stronger, the RS6 performs well all the time, there is no speed limitation and the engine revs into the red without any struggle.
This does not seem to be a limited case, as a friend with an RS6 has a similar problem, with the same symptoms, except that his car goes past 230 km/h, and the fault report is of a low battery voltage.....
The intereting thing is that after the fault was found and fixed, the original software was loaded and the car performs just as well as it did with the re-mapped ECU, in fact even a bit better, 4.74 sec 0-100 k and 12.80 for the quarter mile.
With the (first) original software, back in January my best quater mile was 13.5 sec. only.
It seems that loose cable was causing a loss of performance, as well as causing the chip that learns my driving habits to reset itself to zero from time to time.
If you feel your RS6 is not doing what it should, have your dealer or anyone else with a VAZ computer or VAG.com program, check your car out.
Once the fault is cleared from the computer, it will come back, unless the faullt is attended to, starting with showing a fault in the "alarm" section. With time it will show the same fault in just about all electrical sections.
Another thing; have your DV's checked on a regular basis...., specially aftera few months of hot weather.