People who are more knowledgeable should know that in the torque converter a lock-up clutch is installed. For example, when cruising at a constant speed, the lock-up clutch operates automatically and directly engages the engine and the transmission to reduce power loss. The lock-up clutch is an electronically controlled clutch designed to handle this role.

Torque converter slippage is important during acceleration, but it becomes a liability once the vehicle reaches cruising speed. That's why virtually all modern torque converters use a lock-up clutch.

The purpose of the lockup clutch is to directly connect the engine and the transmission once slippage is no longer needed. When the lockup clutch is engaged, a plate attached to the turbine is hydraulically pushed up against the front cover (which, you will recall, is connected to the impeller), creating a solid connection between the engine and transmission. Having the engine and transmission directly connected lowers the engine speed for a given vehicle speed, which increases fuel economy.

If a vehicle has a heavy enough load, its possible for the lockup clutch to slip, which can cause excessive heat and wear.

WOT TCC: The torque converter clutch can be programmed to lock at Wide Open Throttle (WOT), this usually improves performance and track times. The lockup speed can be programmed from 50 Mph to 105 Mph in 4 mph increments.