Gearshift Maps

[b3lha]

I've figured out the maps for the Torque Converter Lockup. I'll post the technical details of how to decode them on my website in due course.

There are 52 maps in total: 3 modes (Normal, Power, Overheat) multiplied by 4 stick positions ("D","3","2","1") multiplied by 4 gears ("1st","2nd","3rd","4th") makes 48 plus Cruise mode in 4 gears = 52 total.

Each map has a lock curve and an unlock curve. The TC will be locked when the speed rises above the lock curve and unlocked when the speed falls below the unlock curve. The x scale is tps and the y scale is speed. This is the opposite way around the the gear shift maps earlier in the thread. I have converted the scales to a percentage and mph for the picture below.

Most of the maps, for example 1st,2nd and 3rd gear are a straight horizonal line at 159mph. This effectively means "do not lockup the torque converter" because the car is unlikely to ever exceed 159mph in those gears.

If you look at the top left map in the picture below, this is Normal-StickD-Gear4. You can see at 50% throttle, the TC will lock as you accelerate past 77mph and unlock as you decelerate past 55mph. If you were drag racing at 100% throttle, it would lock at 92mph on the way up and unlock at 86mph on the way back down.

It has been mentioned in the "Power Mode Mod" thread that the TC does not lockup in power mode. This is not entirely true. As you can see from the top right map: In 4th gear, it will lock at 92mph and unlock at 86mph in any throttle position.

In the bottom left corner you can see the cruise map, the TC locks up at lower speed and lower throttle for smooth driving and economy.

Finally, in the bottom right corner is a sample of the overheat maps. When the TCU is in overheat mode, it locks up the TC even in 2nd and 3rd gear, not just 4th like the other modes. It has often been said that the TC generates a lot of heat. When the transmission gets too hot, the TCU locks it up whenever possible to try and stop the temperature from rising any further.



These maps were taken from a 1992 USDM TCU.