Ok, i've finally cracked a firmware tables/date and vbf file format, so now i'm able to make a SDD flashable tunes.
It is possible to tweak almost any parametr in a f/w, including
-gear ratios (incl. rear end ratio) - not tested yet, since i don't have a 3.0 diff)
-speed limiter can be tweaked to any speed
-ignition and fuel maps (tested, runs awesome, especially if water/meth is installed)
-revert a f/w to any emission standart
-disable any DTC and perfomance restricions
-A/C cut-off speed and rpm
-fuel cut-off rpm
many other things, the complete list may take a few screens, but i can send it in a .csv file.

So, is anyone intrested?

P.S. tables/data are available for aj-27/later V8 engines, 3.0V6, 2.7&3.0TDV6

I'm definitely curious...

Ok, i need your stock calibration ID and your wishlist

YOU HAVE MY ATTENTION!!!!!!

Yes, yes and yes!

Calibration ID and wishlist

P.S. Now i'm in research to have two tunes - for water/meth and stock. For water/meth i can lean a mixture and advance a spark in a main map, now i have an idea to use a spare table (used i.e. in a case of restricted perfomance) to provide a stock mixture/advance. If everything will go the desired route i'll be able to switch tunes by, i.e. interrupting one single wire with a switch.

Diff ratio to 3.58:1
Faster transmission shifts
Remove torque limitations in ECU
Tweak fuel maps

AJ33S in 2005MY XJR, vin G35785

What other information do you need?

1. Possible, but not guarranteed. As i can see a TCM gets the ratio info from a ECM, but i'm not pretty sure if it will work. Anyway, i'll make two files, one with stock ratios, second with modified
2. For that it'll be needed to redice torque decrease demands, it may give some "hard" shifts
3. 1024Nm limitation would be fine, i guess?
4. Water/meth? octane? Should a spark advance remain stock? Desired AFR for a coast/idle/WOT condition?
5. Vin is enough, i'll check a cal-id in a SDD database.

Ok the stock calibration files are:

z65y5656x350row.phx & z65y5656x350row_data64k.dhx for TCM
n19_s42pm.bin for the ECU

1. I have a 3.58:1 ring & pinion here and a spare diff assembly, but I don't have the 3.0L's 3.31:1 so i'm kind of stuck with that ratio. Easy way to test the file is load it & drive with the "wrong" ratio, if it worked then it'll throw up codes P0720, P0730 & P0780 simultaneously.

2. I think tuning the shifts will need a number of attempts to get it "right" so this might be prio #2

3. The goal here is that the ECU does not "hold back" power unneccessarily, obviously during shifts it needs to reduce torque, but not while in gear at WOT

4. Not interested in water/meth for the time being, just to lean out the target AFR a little. This might also need a few attempts to get right.

Ok, you have a ROW car, so the tune will be 6W93-14C576-BBH.vbf, just like mine is.
1. It throws a codes (i've already tested it), but i'm still not pretty sure if everything will work fine. At least it may require some debugging.
2. Mine shift a little harder now, but that's fine
3. There's a limiter, which limits a maximum torque from an engine, and there's a torque reduction threshold for shifting torque reduction. I can change both of them to a higher limits.
4. Not a problem. I thing it will be better to leave coast/idle AFR as a stock (14.6:1) and to lean a power enrichment target AFR somewhere between a 12 to 13 (but it may cause a detonation in a hot weather or if there's a poor quality fuel). I'm running a 13.5 with a water/meth, no pinging (but, again, it's almost winter over here).

Interested, yes - is there a URL or some such?

I would venture to say that I have a very similar setup as Cambo, but I don't know what I have or where I want it to go as I've not had Anya long enough to know where to go. I don't know where to look to get the info you're requesting yet, but I want to learn. My VIN code is: G40095. 2005 XJR with 108,000 miles on her. THANK YOU!!!

Rags

This all sounds good.

Any chance you can fix the temperature gauge so it gives a real indication?

Nope, no URL yet, the most part of the R&D were completed yesterday, so i had no time to make any documents about it. But they'll be on my site, since, in a future, i have a plans to sell the custom-built f/w for a decent price (not as much as eurotoys or other companies)
Feel free to ask a questions.
For now i have to edit a binaries with a hex editor, manually correct a checksums and so on, but during weekend i hope to write a handy s/w to make this job easier (like a tool to compiler/decompiler/crc calc of vbf files).

So, i guess some kind of conservative-enough setup will be fine?

Not for now. The gauge is driven by an IPC, ECM always sends a correct temp.data. So to fix a gauge someone should mess with a disassembler and IPC f/w.

Does anything in the PCM show what parameters it uses to run the fans aside from temperature? The dealer flashed my PCM with some update and it has it running the fan for 3 minutes after shutdown in hot weather, but it's not based on coolant temp. Seems like it's based on the fuel temperature.

A coplete list of a parameters is availabe at flash - XJ's and XJR's (all bodies)

Coolant temp, oil temp, transmission oil temp, fuel temp, engine bay guard mode.
Also there's a forced OFF period.

Think I'll sit in on this thread

Took a quick glance in an IPC f/w. Can't find any visible map of temp vs needle driver. It is still possible to find it by trials and errors, but i'll need to find a spare IPC, since i'm using an XJR as an every-day car and i don't want to brick it