Cambo, like Brutal is saying, what you want IS possible. I think the hard part for you will be finding someone that can take your ECU and TCM, alter their programming to make them work with the new gearing. Places like Roush, Hennesey, Langendorpher (sp? - the vette modifiers) do this all the time even on the latest and greatest vehicles. Your trick is finding someone that is willing to mess with your Jag. But, any reputable shop should be able to do it for you since the programming is very similar to that of say a Mustang. So, if you have the money to the modification, go for it. If you have done other modifications, this is the prime time to incorporate them too so you can get the most out of your car.

 

Actually what I THOUGHT I was saying Chris, is I dont think there is going to be an issue with programming even being needed
Forgive if I wasnt clear in what I was trying to relate.

 

Brutal, you may be correct in saying that new reprogramming is necessary. But, as I was saying, if the programming is necessary, any speed shop should be able to take care of it as the programming that is necessary is generic to any vehicle.

 

I appreciate your input gents.

I have asked a number of reputable speed shops, hackers, geeks, experienced people and even the manufacturer of the transmission if the software can be modified, the answers have all been no or simply no answer at all. So there are two possibilities;

1. It'll work without re-programming.

2. It won't work at all.

I'm in favour of the big-BRG-***** approach (Brutal you should be a football coach) but i need to have done my homework, so if for whatever reason it doesn't work & i burn a heap of cash, at least I can sleep easier knowing it was worth a shot, based on all the information available.

The software in the Jaguar ZF box is so tightly locked nobody wants to touch it...

Now, if I can confirm that the software file for the 4.2 S/C is the exact same file as the 3.0 and the 2.7D, then that's a good enough indication that "it should be fine"...

 

1st of all you will get an error if you just swap the diff without the TCM programming, this is documented by Jaguar, see attachment.

The 2.7D files will have a totally different shift pattern, and lower rpm, so that’s not an option. The V6 3.0 will be closest, but you need to tune the ECU so it revs at least 100 to 150 rpm higher than the shift point of the V6 files. I would guess that you can increase the max rpm to 6800 or so but you will lose some good torque in that area, maybe diminishing the results you are looking for. I am also a guy that just does things and applaud people doing it as well, but I would do a little bit more preparation here.

1st is upload TCM software form the V6, if that works you will then also find out if the TCM will throw an incorrect gear ratio error which would be good news than ;-). Then reload the original one again, to make the car drivable again, and go to step 2.

2nd tune your ECU so it revs higher than the shift point. You can test this by putting the gear lever in a fixed gear, as then the tcm will not shift down. You can also then test on a dyno how the power delivery is in this new band. Only if that is acceptable, you can actually change the diff imho.

 

Well there goes that plan...

Unless some wizard tuner capable of re-programming the TCM appears out of nowhere, this one is as good as finished.

I don't think it's possible to flash the V6 software into a 4.2 S/C, as it turns out, when you look in the parts catalogue the "Transmission control module & valve assembly, Mechatronic unit" has the exact same part number from VIN G33553 to G49700, for all engine options 3.0L, 3.5L, 4.2L, 4.2 S/C and 2.7D. So yes it seems the file is the same. I'd wager that the TCM talks to the ECM, and bases the diff ratio & shift program on the engine type...

Oh well...an LSD is still on the cards though...

 

Keep writing to SCT Performance - More Power! Less Fuel!, their tool is used for instance in australia by herrod:
Australian Ford Forums
Look at what can be adjusted ;-)

 

Sent SCT an email already and also wrote to Herrod, lets see...

 

No, the programming is only in the TCM and is specific for an engine type, where the TCM does instruct the ECU on power levels during shifting of course, and also exchange some more info.

The My2004 4.2 SC ROW has as main file z65k5662x350.phx, and the 3.0 one z66k5662x350.phx, so they do have different programming. You could maybe send it off and see if others can make something out of the data.

Now if we can find 10 or 20 more people to write, that may help ;-)

 

Ok another thought ide like to know then. How is it that i know people with jeeps, trucks, cars that have regeared and not had issue with trans shifting. I know the trans in my own nissan is adaptive and the tcm is flashed based on vehicle. I dont think jaguar is out there all by themselves in a world of shared parts and technology. Come to think of it on magazine article read on the subject concerning this modification i ve never read about an issue. Change tire diameter yes. Speedo is off and there are programmers for this issue to correct accuracy and a change in size because a tire change throws off the accuracy of the abs and speed. And why is that customer ive seen that have big balled some way bigger tires and wheels than factory do not have issue with shifting only speedo accuracy.(im thinking of 2 cars in particular, 1 with larger 20's and one with a set of custom 24's. Now granted this is like moving down in gearing numerically not up. But you get the point

 

Are you sure about the file names? I reflashed my trans & it used z65y5656x350row.phx

I know what you're saying Brutal, but as an example i've been through the Aussie Ford Forum and it seems every time someone did a diff change on a Falcon with the 6HP26, they had to get it re-tuned. Cruise control stops working, ABS & DSC errors, and so on...

 

Well thats one site im not on

 

Brutal, with trucks, from my experience, they have a box that gets wired into the ABS system to trick the ABS computer into outputting an indication that matches actual. In short, if you can imagine, the ABS sensors are say sending 5,000 pulses per minute to the ABS unit, when in reality, it should be sending say 8,000 pulses. With this box, you can input 5,000 pulses, but the box will spit out 8,000 pulses.

In the case of my truck with 37" tires and 4.56 gears (from the factory 30" tires and 3.73 gears), it just happens that the RPM after gearing is about the same with the larger tires for a given speed as it was in completely stock form. Granted, I ran 35's with the stock gearing and the truck seemed to work fine too. Granted, it did shift alot. I think a lot of it depends on how tight the programming is and how much slop it may allow. Now, keep in mind that my 1997 truck has a 4 speed tranny.

 

The one you mention is listed for the MY2005. To match the MY/Config for the 3.0 you would need the z66y5659x350ww.phx (and z66y5659x350ww_data64k.dhx of course).

 

SCT have replied!

They want to look at the ECM files as well as the TCM files.
Any idea what the 2005MY ECM files for the XJR and 3.0L would be called?

 

That sounds very good, you can send them n19_s42pm.bin for the 4.2 and Xbe_n30Pm.bin for the 3.0

 

only option you have i ids/sdd is wheel size that just changes the rotating circumference

 

A couple of things:
1. they use a slightly different ZF variant I think (has paddle shift)
2. notice the comment about "thud" in the first post - that's "the lurch", i.e. they don't have as standard a fix like we do

However, it's still a step forward and may help those who want to tweak their ZF/diff/PCM.

 

According to SCT Ford has their own TCM and software for the 6HP26 and that's the one they can tune. ZF's own TCM can't be tuned by SCT. I don't know if the Jag unit is ZF or something different altogether.

SCT said once they saw the files they could pretty much give a yes or no answer if it would be possible, I sent them the files 2 weeks ago and a gentle reminder 1 week ago asking if they needed any more information. No reply, but I know the email was read.

So who knows? Yes, No, Maybe, I have no idea what's going on....!!!!

 

SCT have replied;

So reading between the lines, I wonder if they might be able to do something with the later models maybe the "2nd gen 6HP26" used in the X150 as mentioned by Avos HERE