Introduction to Automotive Inlet Pressure Sensor:
Automotive inlet pressure sensor (MAP) is one of the most common sensors on the traditional internal combustion engine, it is mainly responsible for providing engine load signals for the ECU, that is, through the measurement of the intake manifold pressure, indirectly detect the intake volume of the engine, and then through the internal circuit structure of the sensor, the intake volume is converted into a digital voltage signal and provided to the ECU, which in turn affects the vehicle's fuel injection pulse width, throttle opening and other data. The intake pressure sensor is generally installed on the intake manifold, if it is damaged, it will cause the vehicle to appear idle instability, acceleration weakness, difficulty in starting, black smoke and increased fuel consumption and other fault phenomena, and accompanied by engine failure lights lit, and the corresponding control module inside the storage fault code. In general, the most common inlet pressure sensors are three-wire and four-wire, and the pin definitions of the three-wire sensor are power, ground, and intake pressure signals, respectively; while the four-wire sensor has one more intake temperature signal than the three-wire. Let's take a look at how the intake pressure sensor detects it!
Automobile inlet pressure sensor detection method:
Three-wire inlet pressure sensor detection: in the case of opening the ignition switch but not starting the vehicle, using a multimeter measurement, black meter iron, red meter pen respectively to detect three wires on the sensor, will measure a sensor power line 5V, a sensor pressure signal 3V, a sensor ground wire 0V;
In the case of starting the vehicle, using a multimeter measurement, the black meter pen iron, the red meter pen respectively detect the three wires on the sensor, will measure a sensor power line 5V, a sensor pressure signal of about 1.3V (the voltage rises with the engine speed), a sensor ground wire 0V. If the measurement result is different from the above data, it means that there is a problem with the sensor or wiring harness, and the sensor can be directly replaced or the wiring harness can be repaired.
Four-wire inlet pressure sensor detection: As mentioned earlier, the four-wire is only one more temperature signal line than the three-wire, so its detection method is basically the same as the three-wire, at this time we only need to say how the temperature signal line is detected separately. The temperature signal line voltage of the inlet pressure sensor varies very little in both idle speed and high speed range, generally around 3V. In addition, let's talk about how to judge that it is a pressure signal and a temperature signal in the absence of a circuit diagram, in general, the voltage signal that changes greatly between the start and the non-start is the sensor pressure signal line, and conversely, the temperature signal is the temperature signal; and the wire with high voltage when not started is the pressure signal line, and the wire with low voltage is the temperature signal line.
Of course, in addition to the above methods can determine the quality of the sensor, we can also use the diagnostic instrument to read the static data flow of the intake pressure sensor, if the data value read is consistent with the local atmospheric pressure, it means that there is no problem. If there is no such equipment as a diagnostic instrument, we can also use a vacuum gauge to judge, just need to connect the vacuum gauge to the vacuum hose of the intake manifold, you can get a current engine vacuum value, and then use the local atmospheric pressure value to subtract the vacuum value to get the actual intake pressure value of the engine. If the measured intake pressure value is within the standard range, but the vehicle still reports a fault code related to the intake pressure sensor, it means that the sensor is damaged and can be solved by direct replacement.
The above is part of the knowledge about the car intake pressure sensor, I hope to be able to help all the car friends and maintenance masters, reduce the daily use of cars and car troubles!