MAP sensor off car

Manifold Absolute Pressure (MAP)

Does the map sensor match the manufactures specifications, why or why not?

The map sensor match the manufatures specification nearly because the voltage drop within the specification when the vacuum increase.

Does a map sensor read vacuum or pressure?

Vacuum

Explain the internal operation of this sensor and why the output voltage changes

In the MAP sensor, there is a silicon crystal changes in manifold absolute pressure.This silicon crytal change the resistance of the sensor, also in pressure and in resistance.That affects the voltage which allow to flow back the PCM.More pressure is less vacuum which means more voltage output to the ECU and less pressure means more vaccum which means less voltage output to the ECU.