Abstract: Method and systems are provided for operating an engine having a hydrocarbon retaining system coupled to an engine exhaust and an engine intake. One example method comprises, during an engine cold start, routing exhaust gas to the hydrocarbon retaining system to store hydrocarbons in the hydrocarbon retaining system. The method further comprises, during a first purging condition where the exhaust gas is at a first temperature, purging the hydrocarbon retaining system with at least exhaust gas, and during a second purging condition where the exhaust gas is at a second temperature, said second temperature being higher than said first temperature, mixing the exhaust gas with an amount of fresh air to form a purging gas mixture, and purging the hydrocarbon retaining system with said purging gas mixture.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.

Abstract: A system for diagnosing an exhaust temperature sensor in an engine exhaust, the exhaust further including an emission control device, the system comprising an exhaust temperature sensor disposed in the exhaust pathway for indicating temperature; an air/fuel ratio sensor having a heater, the air/fuel ratio sensor disposed in the exhaust pathway; and a control system, the control system enabling and disabling the air/fuel ratio sensor heater based on operating conditions, the controller further adjusting fuel injection to provide a desired air-fuel ratio based on feedback from the air/fuel ratio sensor when the heater is enabled, and determining degradation of the exhaust temperature sensor based on a signal from the air/fuel ratio sensor when the heater is disabled.

Abstract: A system for diagnosing an exhaust temperature sensor in an engine exhaust, the exhaust further including an emission control device, the system comprising an exhaust temperature sensor disposed in the exhaust pathway for indicating temperature; an air/fuel ratio sensor having a heater, the air/fuel ratio sensor disposed in the exhaust pathway; and a control system, the control system enabling and disabling the air/fuel ratio sensor heater based on operating conditions, the controller further adjusting fuel injection to provide a desired air-fuel ratio based on feedback from the air/fuel ratio sensor when the heater is enabled, and determining degradation of the exhaust temperature sensor based on a signal from the air/fuel ratio sensor when the heater is disabled.

Abstract: A method of controlling an engine having a lean NOx trap in the exhaust is described. The method comprises during a first mode, at a first temperature, storing NOx at a lean condition and then purging stored NOx from the NOx trap at a rich condition without concurrently supplying oxygen to the trap during the purging and during a second mode, at a second, lower temperature, storing NOx at a lean condition and then purging stored NOx from the NOx, where an exothermic reaction is generated to temporarily raise the temperature of the trap by supplying oxygen and reductants with an overall rich mixture to the trap during the purging.