Method and system for controlling an engine with enhanced torque control

A method for controlling an engine comprises establishing a torque correction coefficient (KA) to compensate for reducing effect of available engine torque in operating range of different excess air ratios ( lambda ) that are lower than a predetermined value (unity = 1). An initial base desired in-cylinder air mass (tQacb) is determined based on a requested engine torque (tTe). A desired excess air ratio (t lambda ) is determined. The initial base desired in-cylinder air mass (tQacb) is adjusted with at least the desired excess air ratio (t lambda ) and the correction coefficient (KA) to generate a desired in-cylinder air mass (tQac). A desired injected fuel mass (tQf) is controlled based on the desired in-cylinder air mass (tQac) to deliver the requested engine torque (tTe) with the desired excess air ratio (t lambda ) held accomplished.