I had the gearbox in my 03 4.2 replaced with a secondhand one in October, apparently it had done 62k miles, the software was flashed at the time. Initially the gearchanges were quite clunky but they have improved although it always feels like the box is in sport mode whatever position the switch is in. But more concerning is that is has now started holding on to low gears until much higher speeds, the main one being that it rarely changes up from 4th gear until I am doing 70mph - if I get to that and back off it will pretty quickly change to 5th and then 6th gear, and I can slow down and it doesn't change back down immediately. I can sometimes get it to move to 5th at a lower speed by moving the lever to 3rd or 4th and then back to D but it doesn't normally change to 6th this way.

I've got the car booked in for inspection at the end of next week but would be interested in any thoughts. I wondered about disconnecting the battery for a couple of hours to reset everything and see if it continues but otherwise I'm out of ideas.

 

Does the sport switch red LED come on indicating that it is enabled? Or stay off like the switch is disconnected?

The clunky shifts suggest that the drive cycle was not done after clearing the adaptations. This retrains the clutch pressures so the shifts occur properly.

I think it will eventually learn as you drive the car, but my experience of doing the real drive cycle with the dealer scan tool attached is that it is very unnatural to accelerate in the constant and gentle way needed to get the cycle to finish completely.

You might try warming the car up completely and finding a long strait and empty stretch of road. Accelerate very gently letting the car shift up to 5th at about 50mph, then let off and coast until it downshifts to 4th. Then brake gently to a complete stop. Repeat a couple of times and see if it gets better.

 

Check it's not low on fluid.

 

Thanks Guys. The sport switch indicates correct operation, and it does seem to make some difference but not as much as it did before.

One reason I'm taking it back to the garage is to get the oil level checked - it has smelled of oil occasionally since the box was fitted so may be a little low but they did fill it when it was fitted.

 

Pulling the battery cables only resets the ECM adaptations. It does not reset anything in the transmission. To reset the transmission adaptations, it needs to be done with the dealer scan tool or equivalent and or re-flashed. There is a documented Jaguar process to reset the transmission adaptations and shift points and or pump pressures, I will see if I can locate the document.

 

Here is a link to the TSB, for some reason on my MAC I can't save or export the PDF locally, sorry. Maybe someone can do that.

http://www.justanswer.com/uploads/cr...00145NAS11.pdf

Also, another interesting bit of info here about valve bodies in the 6HP26
JAGUAR 6HP26 Rebuilt OEM Valve Body