What problems usually occur after the automobile intake pressure sensor has problems? There are symptoms!

The failure phenomena of automobile intake pressure sensor include

(1) The internal circuit of the sensor is open or short-circuited;

(2) The output signal of the sensor will not change with the change of the vacuum degree of the intake pipe;

(3) The voltage of the sensor output signal is too large or too small, and its value deviates from the normal range;

The connecting line between the intake pipe pressure sensor and the computer is open or short-circuited, the vacuum hose between the sensor and the intake pipe is blocked or leaked, and the vacuum hole of the intake pipe is blocked. , will also make the output signal of the sensor abnormal.

The intake pressure sensor is used to detect the intake air of the engine and control the basic fuel injection quantity. If this sensor is broken, the computer can't receive the intake air, and the mixture will be too thick and too thin, leading to black smoke, incomplete combustion, and even shooting of the exhaust pipe. The mixture will lead to insufficient fuel, backfire, insufficient power, weak acceleration and even difficult start.

Extended data:

ManifoldAbsolutePressureSensor (map) It is connected to the intake manifold through a vacuum tube. With the different engine speed load, it senses the change of vacuum degree in the intake manifold, and then converts the change of sensor internal resistance into a voltage signal for ECU to correct the fuel injection quantity and ignition timing angle. ?

In the EFI engine, the intake pressure sensor is used to detect the intake air volume, which is called D-type injection system (velocity density type). The intake pressure sensor indirectly detects the intake air volume, instead of directly detecting it like the intake air flow sensor. At the same time, it is also affected by many factors, so there are many differences in the detection and maintenance of intake flow sensor, and the faults caused by it also have their particularity.

principle

The intake pressure sensor detects the absolute pressure of the intake manifold behind the throttle. It detects the change of absolute pressure in the manifold according to the engine speed and load, and then converts it into signal voltage and sends it to the ECU. The ECU controls the basic fuel injection quantity according to the signal voltage. ?

There are many kinds of intake pressure sensors, such as piezoresistors and capacitors. Because of the advantages of fast response time, high detection accuracy, small size and flexible installation, varistor is widely used in D-type fuel injection system.

Figure 1 shows the connection between the variable intake pressure sensor and the computer. Fig. 2 is the working principle of the piezoresistive intake pressure sensor. R in figure 1 is the strain resistors R 1, R2, R3 and R4 in figure 2, which form a Whiston bridge and are connected to the silicon diaphragm.

The silicon diaphragm will be deformed under the action of the absolute pressure in the manifold, which will cause the change of the resistance value of the strain resistor R. The higher the absolute pressure in the manifold, the greater the deformation of the silicon diaphragm, and thus the greater the change of the resistance value of the resistor R.. ?

References:

Baidu encyclopedia-intake pressure sensor