Thanks,
@yrwei52. From what
@edmole1 describes, if I did not know the Mazda's transmission, I'd assume he's describing DCT-tranny behavior as the internal clutches wear. Though Mazda's tranny is not a DCT unit, there might be a very similar root cause. There are several sets of clutches internal to any auto transmission that change the gears, and then there's the lock-up clutch pack, which is the one I'm casting a suspicious eye at.
I would expect that after injection of new PCM (powertrain control module) firmware, the vehicle calibrates itself to accommodate stack-up clearances in the mechanics etc. This would explain why new firmware cleared up edmole1's issues and mine. In other words, it might not be the firmware but the update process that benefited the car. Until next time.
It would be good to know how to trigger that reset/recalibration process. You know how disconnecting the battery for a while puts modern cars (including the CX-5) into learning mode? Same idea. In fact, I wonder if that same trick would recalibrate the transmission. Or maybe there's a step or two displayed on the screen of the programming computer that could be performed separately. If not, as a test, it would be interesting to flash the PCM of a misbehaving car with the same firmware rev as it currently contains.
I hope Mazda is monitoring this issue, as the fix could be really simple.
By the way, per the service documentation my 2020 Sig was flashed with firmware PX2K-188K2-B per
TSB 05-002/20 ...oddly, that states "This TSB only applies to US spec vehicles with cylinder deactivation" which the turbo engines don't have. That is additional evidence it is the update process and not the firmware itself that is curing the problem ...perhaps temporarily if edmole1's experience turns out to be typical.
Does anyone know the PCM firmware update process? Is there a step that includes some sort of learning mode?
UPDATE: Per this
post in a Mazda3 forum (relating to jerky acceleration), a user describes their unsuccessful attempt to reset their PCM by disconnecting the battery. Of course, who knows if they did that correctly, but on the face of it there may be another trick or procedure necessary.