Variable displacement engine operation with NVH management

A system for reducing vibration associated with cylinder firing frequency when operating a multiple cylinder internal combustion engine in a reduced displacement mode with fewer than all cylinders combusting fuel, the system comprising:

• an engine controller in communication with the engine, the engine controller operating the engine in a first mode having a first cylinder firing frequency, and a second mode having a second cylinder firing frequency with at least one of the cylinders deactivated;
• a transmission having an input component;
• and
• a device for substantially non-compliantly coupling an output component of the engine to the input component of the transmission so that the input component rotates in a direction opposite to the output component of the engine and to reduce torsional vibration associated with the second cylinder firing frequency while operating in the reduced displacement mode.

A method for controlling a multi-cylinder internal combustion engine operable in at least one reduced displacement mode with fewer than all of the cylinders combusting fuel, the method comprising:

• operating the engine with a first number of cylinders at a first cylinder firing frequency;
• deactivating at least one cylinder to operate in a reduced displacement mode at a second cylinder firing frequency;
• and
• rotating at least one closely-coupled drive train component in a direction opposite to rotating inertia created by operation of the engine to reduce torsional vibrations associated with the second cylinder firing frequency while operating in the reduced displacement mode.