F 250 4WD Super Duty V8-6.4L DSL Turbo (2008)
Manifold Pressure/Vacuum Sensor: Description and Operation
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
Manifold Absolute Pressure (MAP) Sensor
The MAP sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the PCM and returns a voltage signal to the PCM relative to
the intake manifold pressure. The sensor voltage increases as the pressure increases. The MAP sensor allows the PCM to determine the engine boost to
calculate fuel quantity. In addition, the MAP signal is used to control smoke by limiting fuel quantity during acceleration until a specified boost pressure
is obtained, and is used by the PCM for EGR system calculations and control.
A MAP signal concern (an incorrect signal from the MAP sensor), when detected by the PCM, results in the PCM using an estimated, calculated
manifold pressure that is derived from known engine conditions in place of the signal from the sensor.
An open or short in the MAP sensor wiring results in an out of range high or low voltage, at the PCM.
The output of the sensor ranges from 0.175 volts at 28.6 kPa (4.15 psi) to 4.825 volts at 616.5 kPa (89.42 psi). At an atmospheric pressure of 101 kPa
(14.65 psi) the output of the sensor is between 0.67 and 0.82 volt.
