Electronic throttle control of snowmobile with two-stroke internal-combustion engine

A method of controlling a starting mode of a snowmobile having an electronic-control unit (ECU) with a processor, and a 2-stroke combustion engine with an electronic throttle body having a first throttle valve, a second throttle valve, a throttle-position sensor, and an actuator for actuating the first and second throttle valves, comprising:

• determining whether an electronic throttle body drive-voltage generated by the 2-stroke combustion engine is above a threshold voltage;
• determining whether an engine speed of the 2-stroke combustion engine is above a first engine-speed threshold;
• when the generated voltage is at or above the critical threshold voltage and the speed of the 2-stroke combustion engine is above a threshold engine-speed threshold, setting a throttle position of the first throttle valve and the second throttle valve to a neutral-throttle position;
• after a predetermined period of time, determine whether the engine speed is greater than a second engine-speed threshold;
• and
• when the engine speed is greater than the second engine-speed threshold, changing a position of the first throttle valve and the second throttle valve from the neutral-throttle position to an initial throttle-operating position, by controlling the actuator with the processor of the ECU.

A method of controlling a snowmobile having an electronic-control unit (ECU) with a processor, a memory storing one or more throttle-control translation maps, and a 2-stroke combustion engine with an electronic throttle body having a first throttle valve, a second throttle valve, a throttle-position sensor, an actuator for actuating the first and second throttle valves, and an engine-speed sensor, the method comprising:

• storing a predetermined idle-speed throttle-valve position and the one or more throttle-control translation maps in the memory;
• determining with the ECU a throttle-demand valve position, the throttle-demand valve position corresponding to a throttle-demand valve effective area of the first and second throttle valves;
• comparing the throttle-demand valve position to the predetermined idle-speed throttle-valve position;
• receiving at the ECU, an output of the engine-speed sensor indicating an actual engine speed of the 2-stroke internal-combustion engine;
• comparing the actual engine speed with a predetermined engine-idle speed;
• selecting a throttle-control translation map stored in the memory when the throttle-demand position effective flow area is greater than the predetermined idle-speed throttle position effective flow area and when the actual engine speed is greater than the predetermined idle engine speed;
• controlling the actuator using the ECU to set a first position of the first throttle valve in the first throttle bore and a first position of the second throttle valve in the second throttle bore based on the selected throttle-control translation map;
• determining whether an engine fault is present and controlling the actuator using the ECU to set a second position of the first throttle valve in the first throttle bore and a second position of the second throttle valve in the second throttle bore when a fault is present;
• and
• determining whether a ground speed or engine speed exceeds a maximum speed limit and controlling the actuator using the ECU to set a third position of the first throttle valve in the first throttle bore and a third position of the second throttle valve in the second throttle bore to reduce ground speed or engine speed to be less than the maximum speed limit.