Flexible Fuel Sensor
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2000 Mercury Villager, 2000 Mercury Mountaineer, 2000 Lincoln Navigator, 2000 Ford Windstar, and 2000 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The flexible fuel (FF) sensor is a capacitive device with a signal processing stage whose frequency varies with the dielectric constant, conductivity and temperature of the methanol-gasoline fuel mixture in its measuring cell. In general, as the percentage of methanol in the fuel mixture increases, the output frequency of the FF sensor signal will increase. For example, a fuel mixture that is 30% methanol will have a FF sensor signal output frequency between 60 and 100 Hz; 60% methanol will have a FF sensor signal output frequency between 90 and 130 Hz. The PCM uses the percent methanol information to calculate the correct air/fuel ratio and spark advance for the vehicle.