MAP sensor (manifold absolute pressure / air pressure)

The MAP sensor (Manifold Absolute Pressure, sometimes also called Manifold Air Pressure) is used to measure the pressure (floor) in the intake manifold. The sensor transmits information to the control unit (ECU), which uses this information to adjust the fuel dosage for the most optimal combustion.

This sensor is usually located in the intake manifold in front of the throttle valve. In order for the MAP sensor data to be as accurate as possible, a temperature sensor is also required because the MAP sensor output is not temperature compensated (this is only pressure data). The problem is a change in altitude or a change in the temperature of the intake air, in both cases the density of the air changes. As the altitude increases, as well as the temperature of the intake air, its density decreases, and if these factors are not taken into account, the engine power decreases. This is solved by the aforementioned temperature compensation, sometimes with a second MAP sensor that measures the ambient atmospheric pressure. The combination of a MAP and MAF sensor is also rarely used. A mass air flow sensor, unlike a MAP sensor, measures the amount of air mass, so pressure changes are not a problem. In addition, the air can be at any temperature, as there is temperature compensation at the exit from the hot wire.