Abstract: A method of controlling a vehicle powertrain having an automatic transmission coupled to an engine through a lock-up torque converter includes determining when a torque converter unlock is imminent during a deceleration fuel shut-off event, and delaying the resumption of fuel flow to the engine for a calibratable time period to reduce the likelihood of an undesirable increase in engine output torque when the torque converter has not fully transitioned to an unlocked state. The method also includes determining whether one or more breakout conditions exist that require enabling fuel flow to the engine and, perhaps, triggering an active unlocking of the lock-up torque converter.

Abstract: A method of controlling a vehicle powertrain having an automatic transmission coupled to an engine through a lock-up torque converter includes determining when a torque converter unlock is imminent during a deceleration fuel shut-off event, and delaying the resumption of fuel flow to the engine for a calibratable time period to reduce the likelihood of an undesirable increase in engine output torque when the torque converter has not fully transitioned to an unlocked state. The method also includes determining whether one or more breakout conditions exist that require enabling fuel flow to the engine and, perhaps, triggering an active unlocking of the lock-up torque converter.

Abstract: This invention provides a method for controlling a gear ratio in an automatic transmission of a vehicle. The method includes detecting a desired engine braking condition associated with the vehicle. Once the engine braking condition is determined, a decay factor is determined for reducing the gear ratio of the transmission. The decay factor maintains the gear ratio for a delayed period of time before gradually reducing the gear ratio over time. After determining the decay factor, the gear ratio of the transmission is controlled in accordance with the decay factor.

Abstract: A method for controlling a rate of change of speed ratios in a continuously variable transmission (CVT) includes sensing a vehicle speed, sensing an engine speed, and sensing a change in a position of an accelerator pedal. The method includes determining a desired engine speed based on the change in the position of the accelerator pedal, the vehicle speed, and the engine speed. The method includes increasing a target engine speed at a first rate to a predetermined value, wherein the target engine speed corresponds to a speed ratio. The method includes measuring a difference between the target engine speed that is held at the predetermined value and an actual engine speed, and increasing the target engine speed to the desired engine speed at a second rate when the difference substantially equals a predetermined threshold, wherein the second rate is less than the first rate.