The DSG tune turns out to have more influence on the driving experience than I was first aware of. Acquiring an already modified Mk7 GTI meant that the normal driving experience was with an APR Stage 2 TCU tune and the variation in transmission response experienced came with selecting either Drive or Sport mode.
With the acquisition of a second pre-modified GTI, this second one arriving with a Eurodyne Stage 2 TCU tune, how the tuning of the transmission management affects the driving experience became something to investigate.
The difference in behavior of the TCU tunes was not something that was purposefully brought up to investigate but rather by detecting that the car with the Eurodyne TCU tune behaved differently than the GTI with the APR TCU tune.
My expectation of a Drive setting is to lean toward economy and a more laid back driving experience. The Sport mode should live up to the name. From the driver’s seat I was detecting a difference in approaches between the Eurodyne and APR TCU tunes and decided to log each tune to try and identify how they differed.
Eurodyne Stage 2 TCU Tune
First to be recorded was the Eurodyne Stage 2 TCU tune. For the datalogging sessions an area where a range of gear changes could occur was chosen; this requirement fits well with in-town stop and go driving. The recorded data was filtered to exclude conditions where the accelerator pedal was not being depressed.
The gear selection versus vehicle speed is shown on the chart below:
The next chart shows the range of vehicle speed and engine speed over which a particular gear is engaged.
The charts illustrate what was perceived from the driver’s seat, that the Eurodyne Stage 2 TCU tune shifts at fixed engine speeds.
Eurodyne Stage 3 TCU Tune
Interested to see if changing to the Eurodyne Stage 3 TCU tune would change the transmission behavior that software was flashed to the car and another drive was made.
The Stage 3 gear selection versus vehicle speed is shown on the chart below:
Engine and vehicle speed for each gear is shown below:
Overall the Stage 2 and Stage 3 tunes appear to perform similarly. It is unknown how precise the VCDS datalogging software is at capturing gear changes. It is possible some of the variation in the charts is a result of imprecise measurements.
APR Stage 2 TCU Tune
Switching to the GTI operating with the APR TCU tune it was immediately apparent from the driver’s seat that the transmission control logic was different.
The APR Stage 2 gear selection versus vehicle speed is shown on the chart below:
Notably the speed range for 3rd and 4th is wider for the APR tune as well the APR tune reaches 6th gear which did not happen during the datalogging with the Eurodyne TCU tune.
The APR TCU tune vehicle speed and engine speed for a particular gear is shown below:
This chart confirms what is experienced when operating the car, gear changes are a function of more than engine speed.
The transmission control logic employed by APR and Eurodyne produces perceptible differences both as a vehicle operator and in the data recorded during this test.
Understanding how a vendor has programmed the Transmission Control Unit, and the effect on vehicle operation, would be a good subject to research prior to purchasing a TCU tune.