Abstract: An improved method for estimating cylinder flow in an internal combustion engine under all operating conditions is provided. If the MAF sensor is not operational, an estimation algorithm that is independent of a measured throttle flow is used. If the MAF sensor is operational, an estimation algorithm that incorporates a measured throttle flow is used. Further, in order to eliminate abrupt fluctuations that may occur due to switching between two different types of estimates, a “switchover coordinator” algorithm is used to smoothly transition from one type of estimate to another.

Abstract: A method and system for controlling torque disturbances in direct injection stratified charge and lean burn port-fuel injection engines (12) through continuously variable transmission (40). The method and system include using the continuously variable transmission (40) to mitigate the effects of torque disturbances due to a lean NOx trap (22) purge cycle (100). The continuously variable transmission (40) is coordinated with other engine variables, such as throttle (36), fueling rate (Wf), injection timing (&ggr;), and spark timing (&dgr;), to keep the operation near the optimal regime. In periods of trap (22) purge, the engine control variables and the continuously variable transmission (40) are coordinated to maximize purge efficiency for a predetermined period of time. In periods of normal operation (102), the engine control variables and the continuously variable transmission (40) are coordinated to minimize fuel consumption subject to emission constraints.