TunerPro - Limiting torque on 4.0T platform

There are multiple ways to limit torque on the C7/D4 platform using the DS1 and TunerPro RT software.


Quick Refresher on DS1 map tables

Any table in TunerPro RT that exists in the "Flex Fuel/Map switching" folder is copies of maps from other tables in other categories. These overwrite the data in the base map tables based on what "map switch" you are on. Modifying the base tables will have no effect as they are being replaced. Edit the table in the "map switch" you are running. If you want to edit the data in all maps, copy the table to all other "map switches". Some tables are duplicated again, once for gasoline, and once for ethanol.


Bosch table names (codewords)

Notice in the above picture the phrase "KFVNTUXS" was searched by description and found the tables. This is the Bosch name for that particular table in the ECU. These will be mentioned as they are easier to search for than by the description of what the table does. This can be found for any table with "F2" on keyboard or right clicking and choosing "Edit Parameter XDF info".


Torque Control

Since torque is a product of both air mass (boost pressure at a given temp) and ignition advance, limiting boost alone will have the effect of limiting torque.... somewhat. If the ECU can run additional ignition advance due to intake temp, the engine can end up making more torque than what was intended by the limiter. I would not consider boost torque limiting as a "direct approach". However, it can have some advantages if the goal is to only limit torque on specific maps.

The most direct approach to limit torque is to modify the following tables:
  1. Tra_trqMaxGear1_CUR - Characteristic curve (n / trq) gear 1 (Tra_Prt)
  2. Tra_trqMaxGear2_CUR - Characteristic curve (n / trq) gear 2 (Tra_Prt)
  3. Tra_trqMaxGear3_CUR - Characteristic curve (n / trq) gear 3 (Tra_Prt)
  4. Tra_trqMaxGear4_CUR - Characteristic curve (n / trq) gear 4 (Tra_Prt)
  5. Tra_trqMaxGear5_CUR - Characteristic curve (n / trq) gear 5 (Tra_Prt)
  6. Tra_trqMaxGear6_CUR - Characteristic curve (n / trq) gear 6 (Tra_Prt)
  7. Tra_trqMaxGear7_CUR - Characteristic curve (n / trq) gear 7 (Tra_Prt)

And if you are running a RS7 / A8 / S8 with the ZF trans:
  1. Tra_trqMaxGear8_CUR - Characteristic curve (n / trq) gear 8 (Tra_Prt)


Each one of these tables are called "2D". They have only an X axis (engine rpm) and a Z axis (torque in newton meter). The value in red is the output of the table. The table itself is for what gear the transmission is in.

These tables are NOT map switched. Any changes to these will affect torque limiting in ALL maps.


Torque Control by boost - map switched

So maybe you only want to limit torque in a specific map. Because the above tables are not being map switched, limiting boost and therefore torque is an alternative.

  • KFVNTUXS - Max compression ratio from compressor map to protect against overspeed of the turbo (BGRLXVD) Gasoline 0

This is one of many boost limiting tables in the ECU. This table is being both map switched and is duplicated for ethanol. So changes should be made to both ethanol and gasoline tables if your goal is to limit torque for both fuel types. If you are not running ethanol, it is good practice to copy and paste values into both tables anyway. The number at the end of the table description is for which "map switch" the table is being used for. In the above picture, this is for map 0.

If the values may look unfamiliar. This is because of the units. They are not psi, bar, kPa, etc. It is pressure ratio. 

This is a "3D" table. It has an X axis (atmospheric pressure in hPa), a Y axis (engine rpm), and a Z axis (output in pressure ratio).

The downside of adjusting boost pressure in KFVNTUXS will be it is not gear dependent. It will limit boost and therefore torque in ALL gears equally. The ability to limit boost by gear requires utilizing SABRE in the DS1 to create custom caller tables and is outside the scope of this guide. However, Gary Matthews wrote an excellent guide for setting this up here:

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