Variable displacement engine control for fast catalyst light-off

摘要

A system and method for controlling a variable displacement engine include starting the engine with at least one bank of cylinders deactivated to increase load on at least one other bank of activated cylinders and reduce time required for an engine and/or vehicle component to reach a desired operating temperature. In one embodiment, ignition timing or spark is retarded and air/fuel ratio is biased lean for the activated cylinder bank during and shortly after starting to further reduce the time required for catalyst light off and closed loop operation. During activation of a deactivated bank of cylinders, air/fuel ratio of one or more activated cylinders is biased rich with air/fuel ratio of the deactivated cylinders biased lean. In addition, spark is retarded during activation of the deactivated cylinders to reduce the time necessary for components associated with the deactivated cylinders to reach desired operating temperatures.