Controlling downshift questions....

[Jackpine]

Calo, your Dad may be experiencing something that other users of that model year truck don't like, and it seems to be tied in to the new, 6-speed transmission. I think a 4.10 rear end with 35" tires is about equivalent to my 3.73 gears and OEM tires, so I imagine it's geared properly.

As Tico said, the Edge/Gryphon for that model year does not program the transmission, yet, so I doubt he'd see anything MUCH different with it. The engine would produce more power though, and that might be enough to fix things somewhat.

The problem is, he is getting a "part throttle" downshift that is controlled by both engine speed and throttle position. (It's really kind of a "load" commanded shift.) The TCM "sees" a need to drop down two gears to provide the needed power to get up the hill. I see this once in a while in my truck too, especially when towing. 3rd gear isn't quite enough, so it drops into 2nd, which is "way overpowered" for the task. I kind of wish my 3rd gear had a slightly higher ratio than 1:1. It seems like there's not enough difference between it and 4th.

Since I can change the part throttle shift characteristics in my model year, I've corrected this tendency to shift too quickly a bit, but you don't have that option in a 09+ truck.

It's possible that Bill can write a program for the X3 that will adjust the transmission though. You'll have to ask him.

- Jack