Quote:
Originally Posted by SomeRandomer123
But how? What does it change? It must only implement its knowledge of the driver in "D" and "DS" musn't it? Can't change much in Manual mode can it!?
What could it learn? I need to learn it firstly!
Applies for both Standard Auto and Sport Auto.
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Automatic transmissions use hydraulically applied clutches. Shift timing can be controlled by hydraulic pressure, increasing hydraulic pressure will make the shifts faster (clutch application faster). Modern automatic transmissions use input and output speed sensors on the gear set(s) that allow the transmission controller to “know” the amount of slippage and when the shift has completed. The ECU can adjust the hydraulic pressure using an electronic pressure control valve (EPC).
As the transmission friction clutches wear the “fill time” for the shift to complete will change, but with the “self-healing” ability the transmission should shift the same. When the transmission is replaced or rebuilt the adaption values are cleared to allow the ECU to begin the correction process again and the transmission will go through the “relearn” process. Through the process of sensing and adjusting the ECU will create adaption values to allow the transmission to shift consistently during its life.
Having electronic pressure control also allows the transmissions to have several personalities with the push of a button, movement of the shifter, or full throttle signal. The old days transmissions only used two inputs, Vehicle speed and Load (throttle position) which didn’t provide much adaptability. If you wanted a snappy shifting transmission you had to install a shift kit and live with that mode…..today you can just select the mode for your mood.
See also:
http://www.thetruthaboutcars.com/200...transmissions/
Ken Welch
Instructor Automatic Transmissions
Saddleback College