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Home >> Chevrolet >> 1998 >> Venture Base, Van Cargo Extended >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Control System - Theory & Operation >> Computerized Engine Controls >> Input Devices >> Manifold Absolute Pressure (MAP) Sensor
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Manifold Absolute Pressure (MAP) Sensor

MAP sensor measures changes in manifold pressure. Changes in manifold pressure result from engine load and speed changes. The MAP sensor converts these changes in manifold pressure into a voltage output signal to PCM/VCM (1.5 volts at idle to about 4.5 volts at WOT). The PCM/VCM can monitor these signals and adjust air/fuel ratio and ignition timing under various operating conditions.

If MAP sensor fails, the PCM/VCM substitutes a fixed MAP value, and uses the TP sensor to control fuel delivery. A fault in the MAP circuit should set a related Diagnostic Trouble Code (DTC). If a related DTC is not present and MAP sensor is suspected of causing a driveability problem, perform functional check of MAP sensor. See SYSTEM/COMPONENT TESTS article.

CAUTION: Measure O2S voltage with a digital volt-ohmmeter (minimum 10-megohm impedance) only. Current drain of a conventional voltmeter could damage sensor.
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