Map Sensor: Operation: Notes
WARNING: This page is about a different car, the 2006 Chrysler Crossfire. However, it is still accessible from the selected car via links, so may be relevant.
The MAP Sensor monitors the pressure in the intake manifold. The pressure in the manifold moves a diaphragm connected to piezo resistors which alter their resistance values. The output voltage of the resistors serves as information to the PCM about the pressure in the intake manifold.