Technical & Maintenance  |  Upgrades & Style  |  Used A8 Buyer's Checklist

Marketplace  |  On Track  |  Gallery  |  Links |  Contact |  Home

Coding the A8 Transmission
By Paul Waterloo

What Does Recoding Do?
U.S. specification A8's come with transmission coding suitable for a very leisurely driving style. It upshifts early and does not support "spirited driving" like most A8 owners would like to see.

One thing it does not do good is matching engine power and RPM's to the driver's need. When the driver wants to pass or accelerate requiring 40 or 50 additional HP, the transmission does not cooperate. If it did, it would drop one or two gears immediately with a slight depression of the gas pedal. Instead, the transmission stays in gear, and adequate power is not transferred as the driver needs or wants. The driver then depresses the gas pedal further, and finally the transmission downshifts two or three gears and close to 300 HP is applied to the drivetrain.

This lurches the car forward and does not result in what the driver wants; a slight increase in power, in a controlled manner. This surge of power after downshifting two or three gears can cause the car balance to be upset, and if the power is needed to avoid a potential hazard, the transmission is too slow in responding.

By recoding the transmission to the sport mode settings outlined below, the car becomes much more smooth when requesting additional power. The following explains how the TCU controls these shift points and the different software codes already built into all A8's.

The transmission control unit (TCU) controls the transmission by adjusting two position and proportional (throttling) solenoids in the transmission. These solenoids determine gear position, torque converter settings (open, locked and throttling), kick down, etc.

The TCU "learns" the driving style of the driver by summing the way the gas pedal is pushed, i.e. how hard the car is driven. It then develops a dynamic shift program (DSP) index number from 0-256. This is display group 12 under transmission. It has the following four display fields:
  1. How car is driven, load (flat ground - no load "E", hill - load "B")
  2. Dynamic index number (is calculated using driving resistance index and driver evaluation) 0-256
  3. Driving resistance index (is used to calculate dynamic identification number) 0-256
  4. Driver evaluation (Is used to calculate dynamic identification number) 0-256
The following table is from the Bently manual. These measuring blocks can be monitored in display group 12 in the transmission module using the ross-tech software.

The dynamic index number controls how the transmission shifts. If your A8 has the stock transmission coding of 00002, then it sums dynamic index number closer to "old man mode" versus "sport mode".

There are built in software coding that came from the factory that will allow you to shift the software to "sport mode". It differs for the 97 without tiptronic, the 98 and 99 with tiptronic, and the 00 and later with tiptronic. The following explains each.

Transmission Coding for 1997 to 1999 A8's
2000 and later A8's have additional codes explained below.

97 without Tiptronic
If your car does not have tiptronic, it won't hold first gear with the "sport" setting (00011 or 00012). From the factory it came with the coding of 00002, which is the stock setting for U.S. and Canada. 00001 is for the rest of the world. It appears that there is little to no difference between the two "DSP on" settings.

If the transmission is recoded to 00012 (DSP shut off U.S. and Canada), you will find that the transmission holds gears slightly longer, and learns quicker than with the stock coding. It is a slight improvement over the 00002 coding.

It will also take code 00011 (DSP shut off rest of the world). This coding makes the car more of a "European touring machine". It really makes a huge difference in the way the engine and transmission responds. It will shift at higher RPM's and downshift with much less throttle input that the 00002 or 00012 code. The transmission matches the engine speed to the driver's needs, where with the 00002 and 00012 code, the engine speed is too slow for the driver's needs.

98 and 99 with Tiptronic
There are two ways the 98 can be recoded to sport. If recoded to 00012, it acts just like the 97 recode above, with just slightly higher shift points than stock and it learns faster. However, it will not hold first gear to redline in tiptronic unless the driver starts from a stand still and holds the gas pedal to floor. Doesn't solve most aggressive driver's problems.

If coded to 00011, it acts much differently. The following are characteristics of the 00011 code:
This is very different than the 00012 coding. Remember, once you have the ross-tech software, you can always change it from one to another!

00 and later with Tiptronic
The 00's and later have different options than the 99's and earlier. They can be coded as followed: 2002 A8L
The 2002 A8L (from at least one source) came from the factory with transmission coding of 00002. The owner recoded it to 00032, reported as better, but it still did not shift as soon as they would like.

After the car was returned from the Audi dealer after the first service, it was coded as 01002. The owner then recoded it to 01032. The car holds 1st gear to redline and shifts to second.

This coding is very similiar to the S8 coding from the factory.

If you have a S8 and can determine what stock coding is, please email me and report your results. I will update this page.

How to Recode
First, you will need the ross-tech software. It's $200 for the cable and software license. Once you have it, follow these instructions.

  1. Open software and connect to the car.
  2. Turn the ignition on, but leave engine off. The transmission cannot be recoded with the engine running.
  3. See Main Screen, and click on Select Control Module: Select.
  4. See Select Control Module screen, and click on 02-Automatic Trans.
  5. See an Open Controller Screen, and select Recode-07.
  6. See Recode dialog, where you can enter new numbers for transmission software coding (and workshop code). Select "Do it". More information on the codes can be found here.
  7. You should again see the Open Controller Screen, with the new code showing.
  8. The transmission is recoded. You can exit the windows by selecting Go Back two or three times.
  9. Turn off car and disconnect.
It is as simple as that. Enjoy your A8 in sport mode!

Technical & Maintenance  |  Upgrades & Style  |  Used A8 Buyer's Checklist

Marketplace  |  On Track  |  Gallery  |  Links |  Contact |  Home