Ethanol detection with heated fuel injector in flexible fuel vehicles

A method of detecting a percentage of ethanol in fuel used to operate an engine of a flexible fuel vehicle, the method comprising:

• initiating a heating cycle in a heated fuel injector of the engine, the heated fuel injector including a heater that is operated during the heating cycle;
• monitoring the temperature of the heater of the heated fuel injector as a function of time;
• obtaining the heater temperature at a first time t1 at which a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling;
• obtaining the heater temperature at a subsequent time t2 at which the slope of the heater temperature approaches a value of the slope prior to the time t1 and which is greater than the predetermined threshold value indicative of fuel boiling;
• calculating a difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1;
• and
• determining the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1 at which there was a change in slope.

A non-transitory computer readable medium storing a program that causes a controller to execute a method of detecting a percentage of ethanol in fuel used to operate an engine of a flexible fuel vehicle, the method comprising the steps of:

• initiating a heating cycle in a heated fuel injector of the engine, the heated fuel injector including a heater that is operated during the heating cycle;
• monitoring the temperature of the heater of the heated fuel injector as a function of time;
• obtaining the heater temperature at a first time t1 at which a slope of the heater temperature as a function of time reaches a predetermined threshold value indicative of fuel boiling;
• obtaining the heater temperature at a subsequent time t2 at which the slope of the heater temperature approaches a value of the slope prior to the time t1 and which is greater than the predetermined threshold value indicative of fuel boiling;
• calculating a difference ΔT between the heater temperature at time t2 and the heater temperature at the first time t1;
• and
• determining the percentage of ethanol in the fuel as a function of the calculated temperature difference ΔT and the first time t1 at which there was a change in slope.