A method for obtaining an estimate of air charge entering an engine and a method and system for diagnozing a sensor used in such a method

A method for obtaining an accurate cylinder air-charge estimate is presented. First, a sensor-based powertrain. torque estimate is obtained. Next, a torque converter-based powertrain torque estimate is obtained when the torque converter clutch is unlocked. The two estimates are compared, and if they differ by more than a predetermined amount sensor drift can be diagnosed and corrected.