Tuning adjustments for different final drive ratios?

[PantsDants]

So I've been running my 4.88 FD on my 6AT for a few months now and I have to say I'm really enjoying it. Shifts in auto mode are still dead on, speedo still works right, and the bump in acceleration was definitely worth the effort.

Enter tuning. I have an OFT and the new 1.5 map is great, but I can't help but wonder if there are adjustments to be made to the tune to take better advantage of the shorter final drive. This stems from the fact that there are unique stock roms for cars in the EU that have different FD ratios; why would they bother with that if there weren't any mapping changes?

Any ideas guys? Are there any parameters in the map to be tweaked to take advantage of a different FD ratio?

[8686]

Interested to discover more about this as I have the 4.55 FD

[arghx7]

Has anyone done a comparison between the ROMs for different final drives?

[PantsDants]

Originally Posted by arghx7

Has anyone done a comparison between the ROMs for different final drives?

I don't have access to those roms, but I know someone who does... *cough* @shiv@vishnu *cough*

[Luckrider]

Everyone has access to said roms thanks to Shiv. I know I saw the table in RomRaider to edit the gear indicator for manual transmissions. I am sure there is more, but some of it might have to be defined and unfortunately this requires hacking at the bin files to determine what things do.

[PantsDants]

Originally Posted by Luckrider

Everyone has access to said roms thanks to Shiv. I know I saw the table in RomRaider to edit the gear indicator for manual transmissions. I am sure there is more, but some of it might have to be defined and unfortunately this requires hacking at the bin files to determine what things do.

The stock roms are in there too? Hmm... need to check my files again.

[Luckrider]

Each set of tuned ROMs contains a stock rom. Just download the 1.42b and you will have every stock ROM that Shiv has.

[jamesm]

You'll want to adjust the gear limits so that your gear indicator will be correct.

[Luckrider]

Originally Posted by jamesm

You'll want to adjust the gear limits so that your gear indicator will be correct.

I'm not sure how the twins work, but I wouldn't think gear display is a calculation with the autos. Then again, it is much easier for a manufacturer to write one set of code and calibrate it for the different setups.

[SpeedR]

Originally Posted by L8Apex

I have the same 4.88 FD setup as PantsDants in my AT6 (actually followed his instructions to duplicate everything, much thanks!!) and I'm loving it. I'm also curious if the tune can be optimized for the higher final drive.

From what I can see the AT has a speed sensor on the trans output shaft in addition to obtaining the VSS (vehicle speed sensor) signal from wheel sensors. My theory is it uses the speed sensor on the trans to shift the AT at correct shift points, and wheel speed sensors for dash cluster speedo and stability control stuff. The separate speed sensors allow shift logic, speedo, and VSC to all function accurately in spite of the FD change.

Gear indicator on the AT comes from the TCM which uses the trans-mounted speed sensor so it should be unaffected by FD changes on the AT6. But current gear is calculated in the MT6, probably from wheel sensors, and might require an ECU change to fix this, not sure.

Engine tuning itself seems independent from gear ratios so I'm guessing there's no difference in actual tune, but I'm hoping someone can confirm. (Shiv?) I'm not familiar enough with the tables yet.

Thanks for the info.
Can any one confirm this?