Manifold Absolute Pressure (MAP) Sensor
WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The MAP sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the powertrain control module (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 sensor signal is used by the PCM for EGR system calculations and control.