A method and apparatus configured to maintain a desired engine emissions level

The present invention is configured to maintain a desired emissions level of an engine having an intake manifold (118) and an exhaust manifold (122), and an exhaust stack (124) is disclosed. The method includes the steps of establishing a desired emissions level, establishing an engine speed, establishing an engine load, establishing at least one characteristic of one of an intake air and an exhaust gas, and determining a fuel command in response to the engine speed, the engine load, and the desired emissions level, the fuel command resulting in the engine maintaining the desired emissions level.