A method for controlling valve timing of a continuous variable valve duration engine may include: classifying a plurality of control regions depending on an engine speed and an engine load; applying a maximum duration to an intake valve and controlling a valve overlap between an exhaust valve and an intake valve by using an exhaust valve closing (EVC) timing in a first control region; advancing an intake valve closing (IVC) timing and applying a maximum duration to the exhaust valve in a second control region; advancing the IVC timing and the EVC timing in a third control region; controlling the EVC timing in a fourth control region; controlling a throttle valve to be fully opened and controlling the IVC timing in a fifth control region; and controlling the throttle valve to be fully opened and advancing the IVC timing in a sixth control region.

A method for controlling valve timing of a continuous variable valve duration engine may include: classifying a plurality of control regions depending on an engine speed and an engine load; applying a maximum duration to an intake valve and controlling a valve overlap between an exhaust valve and an intake valve by using an exhaust valve closing (EVC) timing in a first control region; advancing an intake valve closing (IVC) timing and applying a maximum duration to the exhaust valve in a second control region; advancing the IVC timing and the EVC timing in a third control region; controlling the EVC timing in a fourth control region; controlling a throttle valve to be fully opened and controlling the IVC timing in a fifth control region; and controlling the throttle valve to be fully opened and advancing the IVC timing in a sixth control region.

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.

Methods and systems are provided for integrating a bi-fuel engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain usage of a current fuel or transition to an alternate fuel based on the cost efficiency of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a fuel transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

Methods and systems are provided for integrating a bi-fuel engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain usage of a current fuel or transition to an alternate fuel based on the cost efficiency of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a fuel transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

Methods and systems are provided for integrating a VCR engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain a current compression ratio or transition to an alternate compression ratio based on the fuel economy benefit of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a compression ratio transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

Methods and systems are provided for integrating a VCR engine with a CVT transmission. Responsive to a driver demand, a controller may determine whether to maintain a current compression ratio or transition to an alternate compression ratio based on the fuel economy benefit of the transition and further based on any engine limitations that may be incurred at the engine speed-load following the transition. To improve the net fuel economy benefit while addressing the engine limitation, a compression ratio transition may be combined with a CVT adjusted engine speed-load regime, while maintaining engine power output.

A stop/start hybrid vehicle includes an engine configured for stopping and restarting during travel, a multiple-ratio transmission, a brake pedal, and an electronic parking brake. The transmission can be shifted into reverse gear either when the brake pedal is applied or unapplied. At least one controller is programmed to control the vehicle under these scenarios. If the engine is off and the brake pedal is applied when the transmission is shifted into reverse, the controller restarts the engine. If the engine is off and the brake pedal is unapplied when the transmission is shifted into reverse, the controller inhibits the engine from restarting until the brake pedal is applied. The controller can also be programmed to apply the electronic parking brake while the brake pedal remains unapplied after a predetermined time from the transmission being shifted into the reverse gear.

A stop/start hybrid vehicle includes an engine configured for stopping and restarting during travel, a multiple-ratio transmission, a brake pedal, and an electronic parking brake. The transmission can be shifted into reverse gear either when the brake pedal is applied or unapplied. At least one controller is programmed to control the vehicle under these scenarios. If the engine is off and the brake pedal is applied when the transmission is shifted into reverse, the controller restarts the engine. If the engine is off and the brake pedal is unapplied when the transmission is shifted into reverse, the controller inhibits the engine from restarting until the brake pedal is applied. The controller can also be programmed to apply the electronic parking brake while the brake pedal remains unapplied after a predetermined time from the transmission being shifted into the reverse gear.