How many sensors are there in an automobile engine, where they are located and what role they play …

1. Crankshaft speed sensor is used to detect the engine speed and determine the top dead center of cylinder 1 (4). The function of crankshaft sensor is to provide crankshaft speed (engine speed) to ECU and judge the ignition time of a cylinder of engine. Without this signal, the engine may stop working or the speed may not be controlled by the throttle.

2. Camshaft position sensor for distinguishing compression top dead center of one (four) cylinders. It is installed at the end of the camshaft of the engine and provides the top dead center signal of the cylinder to the computer. There is only one in-line four-cylinder and six-cylinder engine, and there are two V-shaped engines, which are located at the ends of the intake camshafts of the two cylinder heads. The camshaft position sensor adopts Hall sensor. When the sensor fails and the signal is interrupted, the engine will continue to run and can be started again. However, fuel injection is not completed when the intake valve is open, but before the intake valve is closed (that is, the injection time is increased), which has little effect on the mixture quality and will not affect the overall performance of the engine. At the same time, because the control unit cannot judge which cylinder is about to reach the compression top dead center, the knock adjustment will stop. In order to prevent the engine from knocking, the control unit will automatically reduce the ignition advance angle.

3. The throttle position sensor is used to detect the throttle position of the engine (also used to provide the engine load signal). Also known as throttle opening sensor or throttle switch. Its main function is to detect whether the engine is in idle or load condition, acceleration or deceleration condition. It is essentially a variable resistor and several switches installed on the throttle body.

4. Knock sensor for detecting whether the engine knocks. Knock sensor is also called "knock sensor" (knock, that is, engine jitter). As a feedback element of ignition timing control, it is used to detect the deflagration intensity of the engine, so as to realize the closed-loop control of ignition timing and effectively inhibit the occurrence of engine deflagration. Generally installed about 30CM above the leakage source, or directly installed in the corner of the roof, the country has this standard. The main component is piezoelectric ceramic crystal, and the screw makes the inertial counterweight press the piezoelectric ceramic crystal piece. There are mainly piezoelectric and magnetoelectric types. If the deflagration sensor is damaged, the engine control unit (ECU) will not be able to monitor the degree of deflagration, thus wrongly judging that there is no deflagration. In this case, the engine control unit will increase the ignition advance angle, resulting in rough operation of the engine due to deflagration.

5. Water temperature sensor, used to detect the temperature of engine coolant (providing engine temperature signal). Generally, there should be two, one water tank, one near the engine water outlet, one connected to the computer and one connected to the water thermometer.

6. The air temperature sensor is used to detect the intake air temperature, and convert the intake air temperature into a voltage signal and input it to the ECU as a signal for fuel injection correction. It is a two-wire sensor, one of which is 5THA provided by the engine ECU, and the other is E2 connected to the internal grounding of the engine. Installed on the air inlet pipe or air flow meter. The air temperature sensor is broken, so it can't accurately transmit the signal to ecu. Fuel injection cannot be accurately controlled. It will lead to an increase in automobile fuel consumption. Abbreviation: ATS is an air temperature sensor.

7. The intake manifold absolute pressure sensor is used to detect the intake pressure in the intake pipe. The intake manifold absolute pressure sensor is installed on the front panel. The intake manifold absolute pressure sensor is the main signal used by the engine controller to calibrate the engine fuel supply. MAP reflects the absolute pressure of the intake manifold. When the engine load changes, the pressure of the intake manifold changes, thus changing the resistance of the absolute pressure sensor, thus changing the voltage signal input to the engine controller. The voltage input of the engine controller is related to the atmospheric pressure when the engine is started and the load when the engine is running. The engine controller uses this input signal and the input signals of other sensors to adjust the air-fuel ratio. It is a three-wire pressure variable resistor with high sensitivity. One line inputs the voltage to the sensor, another line grounds the sensor, and the last line is the return signal of the sensor.

8. Air flowmeter, used to detect intake air quality or intake air temperature. The measuring range is 0 ~100L/min. Model: F 103 1, measuring range 100L/min, accuracy 2.5%, analog output 1-5V, and the price is only about 500. There are many forms: valve type (detecting the flow rate according to the opening of the push valve when intake), Karman vortex type (determining the flow rate according to the disturbed airflow intensity when intake), hot wire type (detecting the flow rate according to the heat radiation of the intake air flowing through the thermistor), hot film type (detecting the intake air flow rate according to the heat radiation of the air passing through the hot film), ultrasonic type (detecting the intake air flow rate according to the interference of the intake air to the ultrasonic wave) and vacuum pressure type (pressure type).

9. The accelerator pedal position sensor is used to detect the accelerator pedal position. Failure will cause the following possibilities: keep idling all the time and can't accelerate; Keep a certain speed, changing between 2000 and 3000 revolutions; Maintaining the maximum speed will waste fuel and even damage the engine.

10. Wheel speed sensor for detecting wheel speed. Automobile ABS system is equipped with electromagnetic induction wheel speed sensor, which can be installed in the main reducer or transmission, and consists of permanent magnet, magnetic pole, coil and gear ring.

1 1. The vehicle speed sensor is used to detect the vehicle speed. Generally installed on the transmission output shaft! There is also one installed on the odometer to assist the transmission! After the former fails, the latter plays the role of failure protection. It is usually installed in the drive axle housing or transmission housing, and the signal wire of the speed sensor is usually installed in the shielding sheath, in order to eliminate the electromagnetic and radio frequency interference generated by high-voltage live wires and car phones or other electronic equipment, ensure that electronic communication will not be interrupted, and prevent the driving performance from deteriorating or other problems. Magnetoelectric and photoelectric transducer are the two most widely used speed sensors in automobiles. Magnetoelectric sensors are widely used to control vehicle speed (VSS), crankshaft angle (CKP) and camshaft angle (CMP) in various automobiles in Europe, North America and Asia. They can also be used to sense the speed and position signals of other rotating parts, such as compressor clutches.

12. The oxygen sensor is installed in the front section of the exhaust pipe, where all the exhaust pipe branches meet. Its main function is to detect the oxygen content in the exhaust gas, so as to control the fuel injection quantity. Damage will lead to excessive fuel injection and affect water temperature sensing. Different engines have different oxygen sensors. Generally, the first one is installed before the three-way catalyst, and the second one is installed after the three-way catalyst (the second one is only available in some cars). Old mini-cars generally have only one oxygen sensor, which is installed on the exhaust manifold. Some new mini-cars are equipped with two sensors, and cars are generally equipped with two sensors, called front oxygen sensor and rear oxygen sensor, which are installed in front of three-way catalytic converter and exhaust manifold.

13. Generally, there are two oil pressure sensors, one for low pressure alarm and the other for high pressure alarm. The low pressure alarm is under the valve cover and the high pressure alarm is under the cylinder block. (These sensors are installed in the upper part of the fuel tank and the lower part of the engine block, roughly parallel to the crankshaft),