Abstract

A system (10) for controllably disabling cylinders in an internal combustion engine (12) includes a throttle (18) controlling air flow to an intake manifold (14), a number of cylinder deactivation devices (1001 -100K) and an engine controller (28) controlling fueling (90), ignition timing (94) and throttle position (86). The controller (28) is operable to activate only the minimum number of cylinders required to achieve a desired engine/vehicle operating parameter value, open the throttle (18) to a computed throttle position, control ignition timing sufficiently to drive the current value of the engine/vehicle operating parameter to the desired engine/vehicle operating parameter value, and to then control the flow area of the throttle (18) while also controlling ignition timing to maintain the current value of the engine/vehicle operating parameter near the desired engine/vehicle operating parameter value. The engine/vehicle operating parameter may be engine output torque, engine speed or vehicle speed.