Manifold Absolute Pressure

The MAP sensor is mounted in the engine compartment, on firewall and is connected to throttle body with a vacuum hose. The MAP sensor reacts to absolute pressure in the intake manifold and provides an input voltage to the ECU. As engine load changes, manifold pressure varies, causing the MAP sensors resistance to change. A change in MAP sensor resistance results in a different input voltage to the ECU. This input voltage supplies the ECU with information relating to ambient barometric pressure during engine start-up (cranking), and to engine load while engine is running.