Does anyone know for certain whether the XKR-S TCM is programmed differently than the TCM in the XKR? Does it have a different set of shift points for the gears due to its increased torque?

Also, if you do know for sure, what was the source of the information?

Cheers,
Rick

 

Good question. One that I always wanted to validate. It has been mentioned on the forum the XKR-S has a beefed up torque converter to handle the increased torque of the XKR-S tune. The ZF transmission shifts extremely quick and hard for a slush box.


It would also be good to know the inherit limits of the ZF transmission for members looking at ECM tunes.

 

From what I heard the answer is yes. I just saw a youtube the other day by a English test group that stated the changes of the XKR vs XKR-S. I also believe I saw it on a car and driver road test.Other then the difference in the exhaust system they stated most HP improvements were due to fine tuning the engine controller as well as the transmission.

 

When I researched my XKR 75 article, Jaguar confirmed that the 75 (and by extension, the R-S that was developed from it) has a stronger torque converter. Magazine articles at the time of the 75's release claimed that the standard torque converter was the reason the XKR had always been limited to the standard power/torque levels.

Since the TCM has to select the correct gear & lockup settings to match the engine output and road speed (and a load of other parameters), my assumption would be that it must have at least slightly different settings to accommodate the different converter. However, my notes contain no mention of a different TCM map. That may be because that side of the upgrade was handled by ZF rather than Jaguar.

Anyway, bottom line: I would not try putting the XKR-S TCM firmware onto a standard XKR, even if you could figure out a way to do it, because the gearbox is actually different.

 

I knew Ngarara would chime in on this. Is it the ZF gearbox or just the torque converter that is different?

 

Here was one of the reviews.

It appears the additional 40HP has been gained by improved fuel mapping and freer exhaust.

 

All 5.0 XKs have the same ZF 6HP28 gearbox. The XKRs have a stronger multi-plate clutch system, and the 75 and R-S additionally have the uprated torque converter.

 

Found the reference about the standard XKR being 'limited':

 

Pages 1822-1823 of the 2010 workshop manual provide an exploded view of the torque convertor and a detailed explanation of how it operates. It is a sealed, non-serviceable component, but maybe it would be possible to buy a replacement part for the XKR-S and install it in an XKR to get the beefed up torque handling.

I'm somewhat surprised there's a need for a beefed up part when the overall torque increase at peak is only in the neighborhood of 10%. It's really hard to know what the machine needs versus what sounds good in spec sheet discussions.

I have been reading every discussion of XKR tuning I can find, and so far nobody has complained that they've messed up their transmission by running with increased horsepower post-tuning.

Cheers,
Rick

 

Although the absolute increase is less than 10% the XKR's TCM may be further restricting the full release of any extra power. The XKR-S may have a more aggression TCM tune enabling the full delivery of the extra 10%. If the TCM map on the standard XKR is more conservative than the TCM map on the XKR-S this will translate to 10% plus the TCM map difference. The available dyno charts on this forum should highlight any TCM effect by comparing the run charts of a tuned XKR-S compared to an XKR with the same tune installed. Is this available? Also, very unlikely the numbers will be directly comparable because of different dyno machines and environmental conditions.


However, there is evidence from some dyno runs the power delivery to the wheels has been bled off. What's causing this power to be bled off is unknown. Is it from the SC pulley upgrade or is it the TCM telling the ECM to back off? Has this bleeding off of power been witnessed on XKR-S models or only witnessed on XKR models? If it is only evident on XKR models this will support the conclusion the TCM's map is restricting the power. We also must ascertain if the TCM does indeed function in this manner or simply just maps out shifting behaviour.


Without discounting the above, I think it is safe to assume the XKR has enough over engineering in it's drivetrain to safely accommodate an ECM remap adding another 100hp, as long as the operator doesn't abuse the extra power on a regular bases.


It will be nice, and convenient, to find the answer to your question in the technical documentation. Is there 2 different TCM maps with one only for the XKR-S and it's beefed up torque converter? There is a thread on the XFR forum where, I believe, the TCM has been remapped by some members with the XKR-S or XFR-S map: https://www.jaguarforums.com/forum/x...x-pipe-111588/

 

Just as you can update the XKR with the standard XKR-S software, you could do the same trick for the TCM

Its just finding the right files, renaming and go for it!

Chances are indeed that the TCM is holding back the power, even when all limiters are out of the ECU.

I can have the files checked to see if they are tunable, but I need to know what's in the XKR and in the S model. This you can see with the IDS tool, so if someone could check this would be great!

 

It's possible, I guess, but the ZF transmission looks like a can of worms that would be damn scary to mess with. If you had a spare one to play with, it might be worth a try. Alternatively, you could get the 'box out of a wrecked R-S, but you'd need someone with access to the Jag diagnostic system to 'tell' the car it has new cogs. That's the problem with modern cars - everything talks to everything else, and you can't just swap stuff around.

Manufacturers (normally) have to go for reliability rather than out-and-out performance. I suspect there's a design limit that Jaguar uses, e.g. 85% of maximum rated capability, in order to ensure that they don't end up with thousands of warranty claims. So there's 'slack' in the system that you can exploit when you increase engine output.

Also, it may not be a binary thing, i.e. the situation isn't that it's fine up to a given point and then explodes if you go past that point. It may just lead to increased wear and shorten the gearbox life.

 

I'm expecting to meet with ETG's local installer here in NC tomorrow, so I will ask if he can identify and pull the files from my XKR. My understanding is that the ECM files are checksummed and digitally keyed to each specific vehicle, so I wonder if this would also be the case for the TCM files?

Do you know exactly what I should be asking for? Do we have comparables from any other vehicles? We'll need to get the XKR-S files too.

Cheers,
Rick

 

I'm really interested in what they find as I'm not happy with my current tune and am about to switch. I'm going to hold off to see what you find, but my current tune also changed the TCM parameters.

I'm about to order the Drewtech Mongoose JLR tool so if I'm able to retrieve that information I'll post it.

 

Ask ETG if they use the same ECM tune when they remap an XKR and XKR-S? Both cars have identical engines and the XKR with the dynamic pack/performance exhaust is the same as an XKR-S. If they don't, why? If they do, and I can't see why not, the XKR has substantial gains on the table. They should have lots of info on the TCM, after all this is their business.

 

I do not need the files as these files are already on the IDS, all I need to know is the software partno for the XKR and for the XKR-S , then I can start digging into it (well lets say have people who understand software dig into it, checksums can be adjusted as well).


This partno will be shown when you check it with the IDS tool.

 

Even a clone Mongoose will say and is now about $45.

 

Please point me in the direction of a quality cloned mongoose kind sir

 

JLR Mongoose,JLR Jaguar Land Rover Mongoose--AutoTool-Mall

Although many speak against the use of these cheap knock offs, I have no experience with the clones.

Here is another one:

http://www.aliexpress.com/item/JLR-M..._3282091&vd=30

Also there are some specific requirements for the laptop OS & software versions, etc.

 

try and remember that most parts have operating levels and maximum performance levels. You will not exceed or damage these parts with any of the current tunes available. safety parameters will allow 10-20% more output from any given part. Not to include extended period use and wear in harsh conditions