Abstract: An internal combustion engine's start-up torsional disturbances are reduced by drawing down intake manifold pressure prior to engine cranking. In a preferred arrangement, a secondary air injection reaction pump is adapted for evacuating the intake manifold to effect the desired draw down of the intake manifold pressure.

Abstract: A propulsion system designed for hybrid vehicle's utilizing a first torque path from a coupled motor generator system and internal combustion engine through and automatically shifted manual transmission having a secondary torque path from a secondary torque source to the wheels. The system incorporates the high-efficiency of a manual transmission with the smoothness of the most advanced automatic transmissions by utilizing a second torque path to maintain driver requested torque during shifts. The system is also capable of performing shifts without opening the clutch by utilizing active synchronization of the input shaft RPM combined with the force control of the shifting actuator. This results in fast and smooth shifts that disengage and reengage without unpleasant torque pulsations.