Patent ID: 8397490

Claim:
A method of controlling an engine comprising: operating an engine in a homogenous charge compression ignition (HCCI) mode, wherein the engine includes N cylinders, wherein N is an integer greater than one; monitoring operating conditions of the engine; generating a first predicted condition of a catalyst in response to the operating conditions of the engine; comparing the first predicted condition to a first threshold; operating M of the N cylinders of the engine in a spark ignition mode in response to comparing while operating a remainder of the N cylinders in the HCCI mode, wherein M is an integer less than N; forming first and second operating patterns with the M of the N cylinders operating in the spark ignition mode and the remainder of the cylinders operating in the HCCI mode, wherein the first pattern is different than the second pattern; and controlling a cylinder firing order of the engine according to the first operating pattern, and thereafter controlling the cylinder firing order of the engine according to the second operating pattern.