Theory Of Operation

The Manifold Absolute Pressure (MAP) Sensor and the Intake Air Temperature (IAT) Sensor are combined into one component. The PCM provides a common 5-Volt Supply and sensor ground that is shared by both sensors. Each of these sensors sends feedback to the Powertrain Control Module (PCM) on it's own signal circuit. The MAP Sensor is a transducer that varies resistance according to changes in altitude and atmospheric conditions. With the ignition on and the engine not running, the MAP Sensor provides the PCM with the Barometric Pressure reading. When the engine is running, the MAP Sensor signal supplies the PCM with the current air pressure within the Intake Manifold. The IAT Sensor signal supplies the PCM with the temperature of the air entering the Intake Manifold. This information is used by the PCM, along with other inputs to calculate fuel delivery, and timing needs.