Ranger 2WD V6-3.0L VIN V Flex Fuel (2001)
Flexible Fuel Sensor: Description and Operation
FLEXIBLE FUEL SENSOR
Flexible Fuel (FF) Sensor
The Flexible Fuel (FF) sensor (Figure 30) is a capacitive device that detects the dielectric constant, conductivity and temperature of the fuel being fed
to the engine. From this information, the FF sensor generates a duty cycle frequency that it supplies to the PCM telling it the percentage of ethanol in
the fuel.
In general, as the percentage of ethanol in the fuel mixture increases, the output frequency of the FF sensor signal increases. The relationship between
ethanol alcohol percentage and duty cycle frequency is as follows:
Frequency Table
All duty cycle frequency values are +1/-5%. It is important to note that currently no fuel with greater than 85% ethanol alcohol content is being
produced. The PCM uses the percent ethanol information to calculate the correct A/F (air/fuel) ratio and spark advance for the vehicle.
Beginning in the 2001 model year, not all vehicles are equipped with flexible fuel sensors. On vehicles without flexible fuel sensors, the PCM
calculates the A/F ratio based upon Heated Oxygen Sensor (HO2S) input signals.
