Hello,

It's been years (literally) since my last post, I have been busy battling gremlins on two fronts: engine, and transmission.

I wish to thank Avos for his patience helping me with the engine side of things, I think I see the light at the end of the tunnel.

The transmission, however, is drunk. At WOT, it can barely shift from 2nd to 3rd, and it absolutely refuses to shift from 3rd to 4th. As I approach the shift point, say, after 5000rpm, the power artificially drops, and at ~6000, the acceleration stops, and it just sits there. Driving at light throttle, it behaves perfectly.

Any others have this problem, or know what might cause it? To any guys with the Twin Screw and the 6HP26, how does your trans behave at WOT? I spent around 5k in total, first changing the solenoids, then steels & frictions (twice), rebuild the torque converter, and then finally purchasing an entire new valve body. I really need any help from anyone who has any idea.

On another line, is there still interest in having the 6HP26 upgraded? I am really jealous on the BMW and Audi crowd, they have their 6HP26s with lightning shifts, but even after talking to Simon at Nizpro, they aren't able to access Jag TCUs, and due to low interest they can't afford to dedicate 2-3 months just for my project. Wasn't there a thread back in 2015, when someone had limited success in accessing the calibration? I couldn't find it

 

 

Thanks for the input! There aren't any codes, the car has been sitting at a Jaguar dealership for 2 years - head tech is a friend of mine, and he's in on this - I have full access at any dealer-level tool, if it helps. Mine is a 2004, I thought only the 5.0s have torque limits (6HP28), would mine have them as well?

Thank you about your reference, Viezu also pointed me to Tom Lenthall, I wrote him an email, hopefully it will all be good.

 

It may be worth talking to Cambo and his contact Nick, when they did mine and Simons remap he was able to make changes in the tcu so he may be able to pull codes/change the settings.

Did this fault come on after the ts was fitted? If so it may be the trans response to increased torque (possibly over torque limit?) as a self preservation mode. What sized tyres are you running front to back as a mismatch in diameter can also cause issues with stability control/traction.
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it might be worth monitoring the iat2 sensor via ids to make sure its in speck .
yes it has torque limiters . but i'm sure it just pulls timing .
i cant see how this would prevent a gear shift .
i believe cambo's tune can not modify the torque limiters on the early Denso ECM.
or can but is not as much as the later models .
it would be worth PM,ing him .
i have seen him say before it is not possible to remap the TCM .

i have seen testing with turbo Ford barra 6 engines producing 700+ BHP and 1000nm torque
running through the 6HP26 box , reliably , so the box is strong .
any artificial power loss is generally due to IAT2's pulling the timing or traction control .
however it should stop rev'ing past 6000rpm . the limiter is 5800-6200 .

 

I have to make a confession:
Forgive me, gearbox, for I have sinned - I let it coast in Neutral for a couple of months, I guess I really wanted a Darwin Award. And to add insult to injury, on one of those occasions, I revved it to 4000rpms by accident, and slammed it in gear. That's where it began, it was before the TS. I since rebuilt/replaced everything I could think of, and though it's gotten better, it still refuses to go 3rd-4th. This accentuated after the TS install, now it also has difficulty from 2nd to 3rd, and 4th to 5th.

tires are squared, but even when I had the staggered Sepangs, the car was fine. BTW, does anybody know some WIDE 18" wheels that fit the brembos, and are not hideous?

I am currently talking with somebody in Germany who flashes Audi 6HP26s, he told me to send him the transmission flash files, to see what he can do. Anyone have any idea about how to do that? I will certainly contact Cambo once I can figure out how to delete my inbox, which is full... or Cambo, care to chime in? Last I remember, you were in Australia, right? That's where the software was originally cracked for the 6hp26

 

ouch man thats nasty .

have you tried a TCM reflash , and adaption reset ?
if so and its any thing like mine, it took over 1000 kms before the trans relearned .
jaguar says 3-400 miles mine took a bit longer .
but you have to drive with no sport mode and no fun for the whole time it takes .
i got over anxious too early , and it caused some funky stuff to happen with my shifts too. .
and most probably caused my extended learning process .
you really need to be patient .
i thought the car would learn my traits from the start. as i have read ,
i perceived that it was up to me to teach it a lesson . but really it just needs to learn slowly for itself .

 

unfortunately not the jag software .
, that was for the ford falcon .
there are remaps available for BMW ZF 6HP26's as well .

although with that glimmer of hope and invested interest . cambo may send a jag ZF file to your man for you . i wish you the best on that front .
i think it would be grate to have the jag trans a bit zippier .
but i would also like to be able to switch back to jag lazy mode . because jag

 

Datsports, I was writing the reply while your comment appeared, sorry, and thank you for your input. You brought an interesting thing into discussion: if, par example, I am in 2nd or 3rd, and punch it, the car goes like a bat out of hell, no power decrease, till 6500rpms (not the usual 6100 shift point). Try the same in Drive, and it does what I described earlier. I think the IAT2 would do the same, regardless of manual/automatic mode. If I am wrong, please correct me.

 

ok 6500rpm thats not right
i would not know which module or sensor to blame for an over rev like this .
i would monitor all the sensors for accuracy , mainly MAP ,for load firstly.

jaguar and ZF say adaption reset and consequent relearn process is required if any hardware is replaced .but i guess you did this ?
knowing you must have programed the new TCM when fitted .
and
knowing the ECM and TCM work closely together to orchestrate gear shifts . you may need to update your ECM to match the update on your TCM .?

i agree that may rule out IAT2

also ,i bet it does . i can only imagine .

 

Datsports, if you are ever in Transylvania, I'll treat you to a nice meal of traditional blood sausages and beer, I'm sorry, seems again, you posted as I wrote the last reply

My theory is this: you cannot rev the engine to the limiter in Neutral, like you would a manual car; so you can only watch the gear shift point in each gear (~6100rpm), or take it in manual, and see where the rpm stops. Do this test: while in 2nd (manual), go as far as the rev limiter kicks in - it is an abrupt stop in acceleration, as opposed to the thing that happens in Drive - from 5000rpms onward, power slowly shrinks, until it's the size of a beagle. Is it 6500, or 6200? I'm curious. Our engines are meant to rev, and a 7000 redline would benefit greatly, even for a ported eaton.

So I think those are the trans limiters (the 3.0 V6 is at 6800!!). By the look of the torque curve, at 6000rpms you have the same level as at 4000, so in theory, if you would raise the rpm another 1000, your 600hp motor would be like 700, at the same boost level. If we would fix the ECU / TCU combo, the STRs, and X350s would rule.

I did the adaptations, the head tech at the Jag dealership did everything he could for my car, and I hugely appreciate what he did.

I will try and contact Cambo for his advice on this, I feel like a small fish in a tank waay out of his league

 

 

 

I'm not sure of the specifics of Tom's management yet, I have only got to the enquiry stage with him at the moment, but I do know he has the management in at least one X350...
(at some point I'll have to do a build thread)

 

I'm not so scared of raising the limiter another 1000rpms, I think the engine can handle it. Only worry would be the rods, which are not forged (?), but they are miles ahead of the ones in the 440cui '68 Charger R/T that I am restoring - max power at 4600rpm, but many actually want it to rev to 6000 (bad 3 spd ratio spread, overrev needed in 1st and 2nd for fastest overall acceleration); this close to 40% more - so I think a small increase of 8-900rpm would be safe.

On the fuel side, I have uprated injectors & MAF, so I think I'm safe - only caveat would be the stock, aging pump, thanks for pointing out these safety concerns, it doesn't hurt to also take support mods into consideration.

I spoke to Tom, and I was pleasantly surprised to hear that the standalone ECU he uses interacts with the Jag's CAN network in such a way that you keep all your functions, INCLUDING the ZF 6HP26!

 

 

Alright, well you've got two problems....

#1 you damaged your transmission with the shift into gear at 4000rpm thing, and as you say it was never right since then. So you need a replacement or rebuild, no amount of software fiddling will fix mechanical damage.

#2 there is a torque limiter in the PCM of the 03-05 XJR, S-Type R and XKR. This limiter is defined by Mass Airflow (MAF) vs. engine RPM and throttle position. When you put a twinscrew on the MAF rate goes up, and sooner rather than later you hit that limit. Avos was getting around this by changing the MAF, injectors and a few other things. It can be tuned out, however, I am not going to do any remote tunes on 03-05 cars anymore. These cars are too problematic when it comes to flashing the PCM with IDS/SDD, out of six cars in the last couple of years, only two of them have been smooth sailing. So no more, sorry.

As for the TCM...

ZF are sneaky, they scrubbed the part numbers off the CPUs in the Transmission Control Modules to make it virtually impossible to reverse engineer the files.
Been through this years ago with SCT, and the other tuners who's been able to tune ZF transmissions. Long story short the first 6HP26 in the 03-05 Jags has an orphan TCM, not the same as the Fords, BMW's, or any other makes which have been cracked.
Reverse engineering the files is not feasible.

Flashing the V6 TCM files to the V8 cars doesn't work.
There are two files which are loaded into the TCM, the .phx is the generic file from ZF for that Jaguar-series of 6HP26, and then the .dhx contains the specifics for the particular engine/diff combination.
.phx file appears to be identical for all 03-05 6HP's, the .dhx is model specific. I flashed an X350 3.0L V6 .dhx file into my XJR, had faults up on the dash and it wouldn't even get out of Park. Flashed the correct .dhx file back in and everything was fine again.

 

You can run the jaguar takoba 20" wheels i have on my 04 and run 295/30/20 rear, and 265/35/20 front. They do not rub anywhere but close

 

Simon, isn't cylinder pressure affected by boost, more than rpm? I don't pretend to have expertise on the matter, but I'm thinking that pressure is a reaction to the expansive force of the gas + air mix - don't you have about the same number of molecules at 1000rpm, as you would do at 6000, when all the valves are closed, and the spark ignites the mix? About what you plan to do with forged rods, I also have a little devil on my shoulder, whispering Arden stroker... you know you want to ) But at this stage, I have too many things to sort out, and they're taking a toll on me, gotta do it one at a time.
In any case, thank you for the pointer, I will look into it, I'm glad when I'm given the opportunity to learn something new! I think I have some photos on my old hard drive from 2015, I'll look them up

Cambo, thank you for sharing your experience! I think I may have rushed into writing all the problems I have, and what I wish to achieve, and mixed them up pretty bad. I do not intend to use software as a band-aid; I opened up the transmission two times, the last time I rebuilt the converter, I bought a new mechatronic unit, and again changed all frictions - funny they were Exedy ones, and they were all burnt when I opened the trans again. I have no idea about what else could be wrong. Oh, I also put in a Sonnax Zip Kit. Still having trouble with 2-3, 3-4, 4-5.

As to the torque limiter, right now I am using 50% larger injectors, along with a ProM calibrated for them to fool the ECU (computer shows 45mpg, horay!), so I think that's not the issue. I'm really at a loss as to what's wrong.

The software part was for trying to get the Jag the performance it deserves - at the same power / weight ratio it gets eaten by just about anything else. I'm so sorry you say it failed in 4 out of 6 cars... but that also means you could get the software out of the transmission, have been able to modify it, and then reflash it. Would it be too much to ask you to share how you managed that? The Jag dealer is open to help, but even though they used the original flash tool, they couldn't get the files on a separate storage unit, so that it can be analyzed. I'm willing to take a chance on this project again. Since all 03-05 ZFs are past their warranty, don't you think there's a slim chance that if one would simply ask Jag or ZF for their numbers, they would reveal them? I know it's a long shot, but.... ?

To sum up, could you please tell me, as a first step, how did you get the data to a PC, and such what must I do for that?

Brutal, thank you for your pointer, those wheels look good on the X350! I was thinking of a hybrid Sepang setup, with 10" XKR barrels, and XJ centers, along with a 20mm spacer (can it be done?) - but my priority is parity with the 4wd cars, and I don't think 20s stand a chance for great 60ft times, that's why I'm looking at 18s - to keep with the RS7s etc, I think we'd need something with as much sidewall as possible, and deep in the 3x5s width wise. Something like 345/30R18, or at least 325/35R18, and something like Pilot Sport Cup 2s, if we exclude the drag radials.

 

Well i brought that up cause i know we have people in the 10's with 20's. I run the ken bell 2.6 on my v6 frontier 4 litre and have for 6 years . Factory ecu and tuned for that and 1000cc injectors up from the factory 375's. Its my off road truck as in rock crawling in moab utah but i like to emabarass people on the road that get beat by a lifted 4x4 on mud tires 4.56 gears and 475hp.
I know on my truck that even though you "turn off" traction control it is still there to intervene. To prove the point to a few people i turned off traction and lit up the tires. Then pulled out the abs module fuse(lights up instrument cluster like a christmas tree, no speedo but still shifts correctly) then proceeded to smoke the tires at will non stop till i tool my foot on the gas way more than with traction off.. So maybe youre still getting intervention. Worth a try. I know people on here have run the twin screw without issue on the factory injectors and ecu without issue. So maybe something is being over looked???