Below is the knock sensor, which is located outside the engine body, between the outer walls of the second and third cylinders. Its function is to detect the intensity of the combustion and explosion of the engine cylinders, so as to effectively suppress the occurrence of engine deflagration, which is often called cylinder explosion. What is cylinder explosion? The combustible mixture accumulated in the cylinder explodes and burns irregularly in advance, causing the pressure and temperature of the gas in the cylinder to suddenly increase several times, causing a sharp knocking sound, which will cause the engine to overheat and reduce power, and in severe cases, damage and deformation of the machine parts. This is cylinder explosion. After the electronic control unit recognizes the detonation data, if it exceeds the safety range, it will adjust the advance angle and ignition timing to suppress the occurrence of detonation.

The next one is the coolant temperature sensor, which is located near the coolant outlet on the engine cover. It is responsible for detecting the temperature of the coolant. When the coolant temperature is too low, it will affect the performance of the engine. After the electronic control unit recognizes it, it will adjust the idle speed and ignition timing as well as the concentration of the fuel to optimize combustion and help achieve the optimal operating temperature. If the water temperature is too high, the radiator of the coolant system will be opened to help the engine dissipate heat. At the same time, the coolant temperature will also be displayed on the dashboard.

The oxygen content sensor is located in the exhaust manifold of the exhaust system. It is divided into front oxygen and rear oxygen. In engines that use a three-way catalytic converter to reduce exhaust pollution, the oxygen sensor is an indispensable component. The function of the front oxygen is to detect the oxygen concentration in the exhaust system exhaust gas and send a feedback signal to the ECU, which then controls the increase and decrease of the injector nozzle, thereby controlling the air-fuel ratio of the mixer near the theoretical value. In addition, the function of the rear oxygen sensor is to detect the working condition of the unit catalyst and feed back to the ECU to ensure that the exhaust emissions meet the standards.

The speed sensor is used to detect the actual speed of the car. The electronic control unit can adjust the fuel injection amount according to the vehicle speed to ensure that the engine is in a high-speed working range. At the same time, the vehicle speed information will also be displayed on the dashboard.

The oil pressure sensor is located at the upper end of the oil filter. Its function is to detect the oil pressure value. When the pressure value is normal, the lubrication system can work normally. When the pressure value is normal, an alarm signal will be issued and the oil light on the dashboard will be lit.

These sensors must cooperate with each other and work closely together to complete the engine’s power conversion work. As long as one of them fails, it will affect the normal operation of the engine. Therefore, the sensor is the basis for the normal operation of the engine and is also a strong guarantee for the on-board computer ECU to control the overall situation.

An ordinary fuel engine has about 300-600 independent non-detachable parts. All the parts must work together efficiently and closely to complete the tasks of fuel injection ignition, fuel work and power transmission. Therefore, when the engine is working, there must be a general commander to observe, analyze and issue instructions. The general commander in the engine is the on-board computer ECU, that is, the electronic control unit. The electronic control unit summarizes the operating data collected by various sensors in the engine, analyzes and calculates new instructions, and then sends the instructions to each execution unit for execution. Therefore, the ECU is the brain of the engine, which is responsible for controlling the overall situation. In this process, the parts responsible for sensing various working conditions of the engine are our sensors.

First of all, the air flow sensor is located in the engine intake duct, after the air filter and before the throttle. Its function is to detect the engine’s intake volume and convert it into an electrical signal to transmit to the ECU, which serves as the basis for the ECU to control the amount of fuel injection. Here is a point of knowledge to add, which is the air-fuel ratio. The air-fuel ratio refers to the mixing ratio of fuel and air. The ideal air-fuel ratio is 1:14.7, which means that 14.7 kg of air is needed to burn one kilogram of fuel, so that it can be fully burned.

Next is the throttle, commonly known as the air valve, which can control the size of the air mass entering the engine. This is the throttle position sensor, which is responsible for identifying the opening of the throttle. The larger the throttle opening, the more air enters the engine and the higher the oxygen content, which can be mixed with more mist gasoline to form a more combustible mixture, which can get more power after explosion and combustion. Therefore, the foot-operated accelerator we often hear about refueling is not actually refueling, but increasing the throttle opening to increase air. The throttle position sensor is responsible for identifying the throttle opening information and sending it to the electronic control unit ECU. After analysis and calculation by the electronic control unit, it sends a fuel injection command to the injector. The throttle is generally divided into two types: pull-wire type and electronic type, and most of the throttles on the market are electronic.

Next is the crankshaft position sensor, which is located next to the crankshaft pulley. It is one of the most important sensors in the engine’s electronic control system. It is responsible for detecting the crankshaft’s rotation angle and the engine’s speed. The rotation angle can determine whether the piston is at the top dead center position. Combined with the data from the camshaft position sensor, the ECU can accurately identify when to inject fuel and ignite which cylinder. At the same time, the engine speed information can be displayed on the dashboard, making it easier for the driver to identify the engine speed.

The next one is the camshaft position sensor, which is used to collect the rotation angle of each cam on the camshaft. Based on the rotation angle, the electronic control unit can identify which working stroke the cylinder is in, and at the same time can accurately control the injection timing of the injector and the ignition timing of the spark plug.