Engine control system and methods

A method of controlling a two-stroke internal combustion engine, the method comprising:

• determining a base nominal exhaust gas temperature using a measured exhaust valve position;
• determining an exhaust gas temperature differential by comparing a current exhaust gas temperature to the base nominal exhaust gas temperature;
• generating a short-term ignition correction based on the exhaust gas temperature differential;
• comparing a plurality of measured engine parameters against respective stability criteria, the plurality of measured engine parameters comprising at least a measured engine speed compared to an engine speed gradient, a measured input parameter selected from a measured throttle position compared to a throttle position gradient or a measured crankcase pressure compared to a crankcase pressure range, and the current exhaust gas temperature compared to an exhaust gas temperature gradient;
• incrementing a time-in-correction-zone counter when the plurality of measured engine parameters are within their respective stability criteria;
• applying a long-term ignition correction to the two-stroke internal combustion engine when the time-in-correction-zone counter satisfies a time criteria;
• and
• controlling an ignition angle in the two-stroke internal combustion engine using the long-term ignition correction.

A method of controlling a two-stroke internal combustion engine, the method comprising:

• determining a base nominal exhaust gas temperature using a measured exhaust valve position;
• determining an exhaust gas temperature differential by comparing a current exhaust gas temperature to the base nominal exhaust gas temperature;
• generating a short-term fuel correction based on the exhaust gas temperature differential, the short-term fuel correction being updated at a short-term interval of 50 milliseconds or less;
• simultaneously comparing each of a plurality of measured engine parameters against its respective stability criterion, the plurality of measured engine parameters comprising at least a measured engine speed compared to an engine speed gradient, a measured throttle position compared to a throttle position gradient, and the current exhaust gas temperature compared to an exhaust gas temperature gradient;
• incrementing a time-in-correction-zone counter while each of the plurality of measured engine parameters remains within its respective stability criterion;
• resetting the time-in-correction-zone counter to zero in response to any one of the plurality of measured engine parameters falling outside its respective stability criterion;
• applying a long-term fuel correction to the two-stroke internal combustion engine only when the time-in-correction-zone counter satisfies a time criteria during a continuous interval in which all of the plurality of measured engine parameters remain within their respective stability criteria;
• and
• controlling a fuel injection amount in the two-stroke internal combustion engine using the long-term fuel correction.