I pretty much never use the J-gate and just keep the card in D, but I do find it to be a bit of a pain as the various ECUs conspire to get the transmission into as high a gear as possible with the end result that the rmp ends up at around 1500rpm where there is very little torque.


Now if you want a bit of power, anything more than a tickle on the throttle causes it to immediately drop a gear or two before doing anything, so just when you need a bit of power, what you get is a delay then a lurch into a lower gear. As a result I have started to use the J gate a bit more often.


Is it just me or could we all do with a better transmission algorithm.

 

You described exactly a problem I have ... but for me it's only when going back and forth between 5th and 6th gear.

To minimize it, I stay out of 6th gear altogether (by selecting 5 on the J-gate when I anticipate speeds where 6th might happen) unless I'll be able to stay in 6th for an extended period.

Hoping a reflash will address this as well as the 2nd-to-1st thunk.


I wonder if these issues could be related to the ZF6 being able to lock the torque converter in all gears?? That was new, for ZF, with this box, I think.

 

Try keeping it in Sport mode unless on the highway cruising at a steady speed.

 

Yep, tried that. Sport mode moves the problem up to a higher speed range, about 65-70 MPH vs. about 50-55 MPH in Cruise.

If traffic makes you drift around in that range, it's 5th ... bump-6th ... bump-5th ... bump-6th ...

 

Perhaps they should have included a "Super Sport" mode, but then, that is probably why they did put in the J Gate for the aggressive driver.
I suspect that the thinking when programming the transmission was that the lower the revs, the less fuel being used and the fewer overall revs on the engine.

 

Strange, my 03 XK8 will not shift into 6th when in Sport mode.

 

That's interesting. On my car, in sport mode, it's at about 67 MPH or higher, depending on throttle.


How is the quality of your 5th-6th (up & down) shifting in Cruise mode?

 

Well first I live on an island and hardly ever go over 60 mph. My shifts in all gears up and down are very smooth other than the A drum squeal every now and then when going down from 4th.

The reason I say it does not go into 6th with Sport engaged is I live at elevation 1200' and drive down to sea level routinely on a divided 4 Lane road about 10 miles long. I normally keep the car in a Sport other than on this road as it's just a cruise and no need to keep the revs up. Either up or down hill if I'm in Sport at speed, 55-60, and turn sport off the car up shifts and the revs drop. If I turn sport back on it down shifts and the revs increase. This only happens at speed.

 

That is my thinking also, they sacrificed drivability for fuel economy/emissions.

 

This thread made me interested so I read the jtis on Trans Programming, just appending here as tourist info

Special Shift Programs
These specific condition shift maps are available to enhance the operation of the vehicle under specific driving conditions. and are listed below in order of priority / title and operating condition.
Traction: When traction intervention is active
Hot mode: Extreme engine / transmission temperatures
Gradient: Under specific speeds and loadsCruise: During cruise control
Manual: Shift map when the LH side of the 'J gate' is used

Three specific condition shift maps have a higher priority than the two base shift maps and will intervene when appropriate conditions prevail for traction, gradient or cruise.When traction control (engine or brake system derived) is operational the TCM will implement the traction map to maximise control of wheel slip.The gradient maps are intended to enhance vehicle drivability when towing or climbing a gradient. The TCM will implement the maps when increased driving resistance is detected and enhanced drivability, cooling and increased performance is appropriate.The cruise map is intended to minimize unwanted gearshifts and 'hunting' and is activated when cruising near to the set speed, or resuming.