DUAL FUEL COMBUSTION CONTROL BASED ON COVARIED SPARK PRODUCTION AND PILOT SHOT DELIVERY

Operating a dual fuel engine system includes igniting a main charge of gaseous fuel in response to combustion of an early pilot shot of liquid fuel and production of a spark. Operating the system also includes covarying a spark timing parameter and a pilot shot delivery parameter, and reducing an error in a phasing of combustion of another main charge based on the covarying of the spark timing parameter and the pilot shot delivery parameter.