Hi all;
I have a 98 xk8 convertible. I happen to have a trans from a 2002 xjr with its control box. How hard would it be to upgrade to said mercedes unit?
Thanx,Don

 

I suspect that, at least, you'll run into grief with the ECM. The part for the supercharged 98/99 is different, and doesn't know about VVT. IDK if your existing one can be reprogrammed.

The gearshift linkage is probably also different.

 

+1 on communication errors that cannot be easily resolved.

 

As well as the linkage, there is the driveshaft length and connection to differential (flange or Jurid depending on XK8/XKR/XJR), and rear transmission mount possible differences.

On canbus messaging, there is some commonality across 5HP24 and 722.6 at least for AJ27 ECU (i.e. same canbus IDs are used), but whether all the messages are the same (i.e. if Jaguar was able to get Mercedes and ZF to align on absolutely everything is a big unknown). Since the TCM talks to the ECU and ABS and INST, it is reasonable to think Jaguar pushed for as much alignment as possible, but loading different software in all of these modules would not have been a big deal to Jaguar, as long as the hardware was the same.

Per michaelh the AJ26 XKR ECU software (for 722.6 transmission) is not compatible with an XK8 engine (VVT/no VVT, supercharged or not, totally different compression ratio, different injectors, etc.). So you will have to use the XK8 ECU software load (unless you swap in an XKR/XJR engine).

There are many messages sent from the TCM to ECU across the two canbus IDs it uses (see crbass threads for details). Since 5HP24 and 722.6 are used for both AJ26 and AJ27 ECUs this potential commonality could also also span across AJ26 and AJ27.
So if you have time on your hands, you could try it and see what happens, but it is a total lottery given the amount of chatting between the ECU and TCM (gear positions, oil temps, torque reduction requests, trans input and output speeds, torque converter slip and status, kick down, fault conditions, traction control, shift energy management, etc.). Seems pretty risky to me.

 

It is really easy to do. You just need a matching engine with a blower and its ECU.

 

Hi all;
Looks like another big Jaguar production. Actually I have the engine, I considered swapping the whole unit, but everyone knows what a production that is. Thanx everyone for your input. How about this? Any thoughts on a 6speed zf swap?
Don

 

The 4.2L electronics will be even more of an obstacle for that

 

I agree ^^^, 6 speed ZF I believe was introduced together with the change from AJ27 4.0 liter to AJ34 4.2 - different ECU from different manufacturer (from Denso to Bosch I think). I would guess 6 speed ZF TCM would be really unlikely to work with AJ26 XK8 ECU as everything has the potential to be changed.