Key reason for dropping into neutral is this is when the torque converter really loves to overheat. Knowing this for years, would shift into neutral with an AT if I knew I was going to be stopped for any period of time. Really not much to do with fuel economy, killing the engine when stopped helps this.
Surprised the fix is in the clutch drive plates, deals more with the geek that wrote the firmware. Has two parameters to deal with, Vss will be at zero, and tach speed.
Kind of like the good old days, Supra runs a TB cable to the AT, can be adjusted for glass smooth shifts, TH400 does this with a vacuum modulator for the same effect and is adjustable. Now all firmware with esoteric source code.
When control valves were used, a piston type valve, when one clutch received line pressure, was completely released before the next clutch was activated, completely fool proof. But these were were replaces by valve solenoids control by a microcontroller with software. A far cheaper approach, but forget about the price tag.
They got it right on my 92 DeVille, because the software was burnt into PROM, and non-erasable. But with flashram and easy internet updates, getting pretty darn sloppy.
Seems like clutch problems would relate to other transmission shift problems, a series of plates that are compressed together and do wear out, stick, bind, or don't engage at all.
