Flexible Fuel (FF) Sensor

FF sensor is a capacitive device with a signal processing stage. FF sensor is located in engine compartment, high-pressure fuel supply line between fuel mixer and fuel rail. FF sensor frequency signal varies according to conductivity and temperature of methanol-gasoline mixture. As percentage of methanol in fuel increases, output frequency of FF sensor signal will increase. For example, a fuel mixture that was determined to be 30 percent methanol will result in FF sensor signal output frequency being 60-100 Hz. Sixty percent methanol will result in FF sensor signal of 90-130 Hz. The PCM uses FF sensor frequency signal to calculate correct air/fuel ratio and spark advance.