LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2003 >> Impala Police >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation - 3.8L >> Computerized Engine Controls >> Input Devices >> Manifold Absolute Pressure Sensor

Manifold Absolute Pressure Sensor

Without Supercharger (VIN K)  - The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure which gives an indication of the engine load. The MAP sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. With low MAP such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high MAP such as ignition ON, engine OFF or Wide Open Throttle (WOT), the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 10-104 kPa. The MAP sensor is also used to calculate the Barometric Pressure (BARO) when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is intermittently high or low, a DTC sets.

With Supercharger (VIN 1)  - The MAP sensor responds to changes in intake manifold pressure which gives an indication of the engine load. The MAP sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM supplies 5 volts to the MAP sensor on the 5-volt reference circuit and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. With low MAP such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high MAP such as WOT, the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 8-208 kPa. The MAP sensor is also used to calculate the BARO when the ignition switch is turned to RUN position, with the engine OFF. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is intermittently high or low, a DTC sets.