Engine control for low emission vehicle starting

A method for operating an engine with an emission control device in an exhaust system of the engine, and an air introduction device coupled to the engine exhaust system, the method comprising:

• after an engine start, operating the engine with ignition timing retarded from optimal torque timing and combusting a lean air-fuel mixture;
• continuing said operation until an exhaust system temperature reaches a pre-selected value;
• and
• after reaching said pre-selected temperature value, operating the engine with a rich air-fuel mixture and commencing adding of air via said air introduction device, wherein said exhaust system temperature is an exhaust manifold temperature and said pre-selected value is an auto-ignition temperature.

A method for operating an engine with an emission control device in an exhaust system of the engine, and an air introduction device coupled to the engine exhaust system, the method comprising:

• in response to an indication that exhaust temperature is below a first threshold, operating the engine with ignition timing retarded from optimal torque timing to combust a lean air-fuel mixture;
• in response to an indication that exhaust temperature is above said first threshold and below a second threshold, operating the engine to combust a rich air-fuel mixture and adding air to the exhaust system via said air introduction device;
• and
• in response to an indication that exhaust temperature is above said second threshold, operating the engine near stoichiometry.

A method for operating an engine with an emission control device in an exhaust system of the engine, and an air introduction device coupled to the engine exhaust system, the method comprising:

• when exhaust temperature is below a first threshold, operating the engine with ignition timing retarded from optimal torque timing to combust a lean air-fuel mixture;
• when exhaust temperature is above said first threshold and below a second threshold, operating the engine to combust a rich air-fuel mixture and adding air to the exhaust system via said air introduction device;
• and
• when exhaust temperature is above said second threshold, operating the engine near stoichiometry.