Patent ID: 8443587

Claim:
Method for operating an internal combustion engine selectively operative lean of stoichiometry, the method comprising: fluidly coupling a first aftertreatment device to exhaust ports of a first set of combustion chambers of the internal combustion engine; fluidly coupling a second aftertreatment device to exhaust ports of a second set of combustion chambers of the internal combustion engine; fluidly coupling a third aftertreatment device including a first supplemental heating device to outlets of the first and second aftertreatment devices; starting the engine after an extended off period; and only when the temperature of the third aftertreatment device is less than a minimum threshold temperature defining a minimum acceptable temperature for the third aftertreatment device to effectively oxidize NOx in the exhaust gas feedstream and only after the first and second aftertreatment devices achieve respective temperature thresholds where each respective temperature threshold defines light-off temperatures of the respective first and respective second aftertreatment devices, enabling a lambda split fuel injection strategy comprising operating the first set of combustion chambers at a rich air/fuel ratio and operating the second set of combustion chambers at a lean air/fuel ratio and operating the first supplemental heating device to transfer thermal energy to an exhaust gas feedstream and only retarding spark timing of the first set of combustion chambers.