I'd have to see what you are talking about, but I don't think it's broken, just the 9 speed and the firmware fixes to avoid certain problems. For fuel economy, it will try ot get to 5th as soon as possible. Because the 4-5 shift is one of the ones with a dog clutch, it takes longer. Based on owner complaints some things were changed about the firmware's shifting strategy. A couple of things that it definitely does differently now is if it detects deceleration, it avoids a downshift for longer, especially the longer shifts that involve a dog clutch, so that you are at least in a gear if you get back on the throttle. It'll also hold gears longer before upshift under certain conditions compared to early revisions.
In general, it has always been willing to get into the area of lugging the engine to hit the right numbers for fuel efficiency. I suspect owners would be happier if they just bumped up the target cruising rpms a bit and avoid getting into that near lugging zone. But I suspect that would worsen their problems with the EPA.
Never said anything was broken. When I get to a speed change of say 55-65 to 35-40 sometimes it hangs in 5th and i get this rumble/growl and slight vibration through the pedals when I start hitting the gas again. I pull the shifter to Manual and drop the gear to 4th and problem solved. 30-35 is too low of a speed for 5th to be engaged and get slow gears or some mismatch I think.
I need to pay attention to the RPM i know the needle was below 1500 when this happens.
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