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happen if my map sensor went out on my 2005 gmc envoy 4.2 4wd

Customer Question

what would happen if my map sensor went out on my 2005 gmc envoy 4.2 4wd
Submitted: 7 years ago.
Category: GM
Expert:  MPMoore replied 7 years ago.
If the Map sensor was bad, the check engine light should come. The engine would lack power and run erratic. You would get a hesitation or stumb when accelerating. Fuel milage would go down.

This is a desribtion of how the engine computer uses the map sensor.

Circuit Description

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:

A 5-volt reference circuit
A low reference circuit
A MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also 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. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide-open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs 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.

The PCM calculates a predicted value for the MAP sensor based on throttle position (TP) and engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. If the PCM detects that the MAP sensor signal is not within the predicted range, DTC P0106 sets.

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