MAP sensor DTC problems
MAP sensor, depending of the type (see Automobile electronics & 4-stroke engines), changes the output voltage as the vacuum changes in the engine inlet manifold, and it is the one of the parameters that ECU uses to determine the moment of ignition and dosing fuel. Malfunction of this sensor will affect the engine performance and may be manifested by slow acceleration, lack of power etc.
As it was the case with the O2 sensor, here we can also look for problem in a vacuum leaks. If the engine is equipped with TPS sensor, we can compare the values of voltage oscillation on both sensors, which should be proportional. Regardless, whether on one of these sensors value rises or falls during acceleration, the value must be proportional on both sensors. Suppose, that by opening the throttle at the engine inlet manifold TPS sensor indicates voltage deviation by plus or minus, the same situation we should meet at MAP sensor.
As it was the case with the O2 sensor, here we can also look for problem in a vacuum leaks. If the engine is equipped with TPS sensor, we can compare the values of voltage oscillation on both sensors, which should be proportional. Regardless, whether on one of these sensors value rises or falls during acceleration, the value must be proportional on both sensors. Suppose, that by opening the throttle at the engine inlet manifold TPS sensor indicates voltage deviation by plus or minus, the same situation we should meet at MAP sensor.
Vacuum is the strongest when engine is running at minimum RPM (idle). By opening the throttle vacuum is reduced, and the MAP sensor registers it by stronger or weaker voltage signal. If there is not TPS sensor installed, we are measuring MAP sensor output voltage at different engine RPM. If after these checks, there are doubts about the accuracy of the sensor, we should check the power supply on the connector and per- form the identical test previously described.
Disconnect the vacuum hose from the intake manifold and monitor the changes of output voltage values. If the power supply is correct and we do not notice the change of sensor output voltage at this test, we can conclude that the sensor is defective. If we use the OBD II program for such test and choose the option Sensor data we can read the pressure values at different engine speeds (RPM). The value of pressure is shown in row Intake Manifold Pressure.
On the shown graph we see the reaction of the MAP sensor when vacuum oscillates in the engine inlet manifold. By increasing the engine speed, or opening the throttle, the vacuum in the engine inlet manifold drops and sensor output voltage increases.
Disconnect the vacuum hose from the intake manifold and monitor the changes of output voltage values. If the power supply is correct and we do not notice the change of sensor output voltage at this test, we can conclude that the sensor is defective. If we use the OBD II program for such test and choose the option Sensor data we can read the pressure values at different engine speeds (RPM). The value of pressure is shown in row Intake Manifold Pressure.
On the shown graph we see the reaction of the MAP sensor when vacuum oscillates in the engine inlet manifold. By increasing the engine speed, or opening the throttle, the vacuum in the engine inlet manifold drops and sensor output voltage increases.