Exhaust gas control using a spark plug ionization signal

A method of controlling exhaust gas re-circulation comprising using a measurement of minimum best time for best torque timing to control exhaust gas re-circulation, said measurement of minimum best time for best torque timing comprising a spark timing at which maximum torque occurs for a given set of engine operating conditions wherein said step of using minimum best time for best torque timing criterion to control exhaust gas re-circulation further comprises the steps of:

• running an engine at an exhaust gas re-circulation minimum best time for best torque spark timing when said engine is not knock limited;
• and
• running an engine at an offset from said exhaust gas re-circulation minimum best time for best torque spark timing when said engine is knock limit, wherein said step of running an engine at an offset from said exhaust gas re-circulation minimum best time for best torque spark timing when said engine is knock limited comprises setting the exhaust gas re-circulation rate to a knock limited exhaust gas re-circulation rate.

A method of controlling exhaust gas re-circulation comprising using a measurement of minimum best time for best torque timing to control exhaust gas re-circulation, said measurement of minimum best time for best torque timing comprising a spark timing at which maximum torque occurs for a given set of engine operating conditions, wherein said step of using minimum best time for best torque timing criterion to control exhaust gas re-circulation further comprises the steps of:

• running an engine at an exhaust gas re-circulation minimum best time for best torque spark timing when said engine is not knock limited;
• and
• running an engine at an offset from said exhaust gas re-circulation minimum best time for best torque spark timing when said engine is knock limit, wherein said step of running an engine at an exhaust gas re-circulation minimum best time for best torque spark timing when said engine is not knock limited comprises setting the exhaust gas re-circulation rate to an optimal exhaust gas re-circulation rate.

A method of controlling exhaust gas re-circulation comprising using a measurement of minimum best time for best torque timing to control exhaust gas re-circulation, said measurement of minimum best time for best torque timing comprising a spark timing at which maximum torque occurs for a given set of engine operating conditions, wherein said step of using minimum best time for best torque timing criterion to control exhaust gas re-circulation further comprises the steps of:

• running an engine at an exhaust gas re-circulation minimum best time for best torque spark timing when said engine is not knock limited, wherein said step of running an engine at an exhaust gas re-circulation minimum best time for best torque spark timing when said engine is not knock limited comprises setting the exhaust gas re-circulation rate to an optimal exhaust gas re-circulation rate;
• and
• running an engine at an offset from said exhaust gas re-circulation minimum best time for best torque spark timing when said engine is knock limit, wherein said step of running an engine at an offset from said exhaust gas re-circulation minimum best time for best torque spark timing when said engine is knock limited comprises setting the exhaust gas re-circulation into to a knock limited exhaust gas re-circulation rate.