Views: 85 Author: Site Editor Publish Time: 2020-03-25 Origin: Site
The development of automotive technology is increasingly dependent on sensors. The sensor detects the signal and feeds it back to the car computer. The computer controls the corresponding components to work. If the sensor is damaged, the corresponding parts will not work properly. Therefore, automotive sensors have a very important position.
The eight major automotive sensors we are talking about include: air flow sensors, intake air pressure sensors, throttle position sensors, water temperature sensors, camshaft position sensors, crankshaft position sensors, knock sensors, oxygen sensors. Today we will introduce the first four sensors.
Currently, there are mainly two types of air flow sensors: hot-wire air flow sensors and hot-film air flow sensors, which are generally installed between the air filter and the throttle. The main function of the air flow sensor is to calculate the air flow per unit time. Air flow is one of the basic signals that determines the amount of fuel injected. After the air flow meter fails, the ECU cannot detect the true intake volume of the air, which results in an imbalance in the mixture. The imbalance of the mixture will cause many failures such as unstable idling, weak engine, increased fuel consumption, and excessive exhaust gas. Even when we shift gears, the car goes out.
The intake pressure sensor is divided into a resistive intake pressure sensor and a capacitive intake pressure sensor. It is mounted on the intake manifold and is usually integrated with the intake temperature sensor. The intake pressure sensor can detect the absolute pressure of the intake manifold, and then it can detect the change of the absolute pressure in the manifold according to the speed and load of the engine. This information is then converted into a signal voltage and sent to the ECU. The ECU controls the amount of basic fuel injection based on the magnitude of this signal voltage.
If the intake pressure sensor fails, the following symptoms will appear:
(1) The engine cannot work normally.
(2) The idling speed of the car is unstable.
(3) The car often stalls or fails to start.
(4) The fuel consumption of automobiles is amazing.
Throttle position sensor is divided into switch contact type throttle position sensor, linear variable resistance throttle position sensor and comprehensive throttle position sensor. A throttle position sensor is installed on the throttle, which detects the opening of the throttle. It interacts with the throttle through a lever mechanism to reflect the different operating conditions of the engine. Throttle position sensor can detect different operating conditions of the engine and input them to the ECU to control different fuel injection amounts. If the throttle position sensor malfunctions, the engine computer cannot correctly receive the throttle opening signal, resulting in inability to accurately adjust the fuel injection amount and the ignition timing.
Causes of Throttle Position Sensor Failure:
(1) The idle switch is short-circuited or disconnected.
(2) The throttle position sensor is improperly installed and adjusted, so that the idle switch is not closed when the throttle is fully closed. Another situation is that the idle switch is still closed when the throttle is open to a certain degree.
(3) Poor contact of the sliding contact of the internal linear variable resistor. This is because the throttle position sensor output signal is intermittently interrupted during the process of the throttle from fully closed to fully open.
If the throttle position sensor fails, the car will have the following symptoms:
(1) The engine idling is abnormal.
(2) The engine accelerates abnormally (for example, the engine is shaking, and the response is delayed).
(3) Occasionally, it may cause intermittent jitter during engine operation.
The water temperature sensor is actually a semiconductor thermistor. The lower the temperature, the greater the resistance; the higher the temperature, the smaller the resistance. The water temperature sensor is installed on the water jacket of the engine block or cylinder head, and it is in direct contact with the cooling water. It is used to detect the temperature of engine cooling water. The ECU corrects fuel injection and ignition based on the water temperature signal.
If the water temperature sensor fails, the car will show the following symptoms:
(1) It is difficult for a car to start cold.
(2) The oil supply is abnormal.
(3) Weak acceleration.
(4) Tempering during rapid acceleration.
In addition to these sensors, tire pressure monitoring systems are also important for cars. TPMS is a device to ensure driving safety. It can monitor the tire pressure in real time, and alarm when the tire leaks and the pressure is too low.
