1. Detailed explanation of the function of the camshaft position sensor
The function of the camshaft position sensor is to collect the camshaft angle signal and input it into the electronic control unit (ECU) for Determine the ignition time and fuel injection time.
The camshaft position sensor is also called the cylinder identification sensor. In order to distinguish it from the crankshaft position sensor (CPS), the camshaft position sensor is generally represented by CIS. The function of the camshaft position sensor is to collect the position signal of the valve camshaft and input it into the ECU so that the ECU can identify the compression top dead center of cylinder 1 to perform sequential injection control, ignition timing control and knock control. In addition, the camshaft position signal is used to identify the first ignition moment when starting the engine. Because the camshaft position sensor can identify which cylinder piston is about to reach top dead center, it is called a cylinder identification sensor.
The function of the camshaft position sensor: the camshaft controls the intake and exhaust valves. It rotates at half the crankshaft speed. Its position determines whether the piston moving up to the top dead center is at the top dead center of the compression stroke or the top dead center of the exhaust stroke. . During the starting process, it is impossible to distinguish the two top dead centers from the crankshaft position signal alone. At this time, the camshaft position sensor plays the role of accurately determining the position of the compression top dead center.
In contrast, when the vehicle is running, the signal generated by the crankshaft speed sensor is sufficient to determine the status of the diesel engine. This means that if the camshaft position sensor fails during vehicle operation, the ECU can still determine the status of the diesel engine.
The camshaft position sensor uses the Hall effect to determine the position of the camshaft: a tooth made of ferromagnetic material is provided on the camshaft, which rotates with the camshaft.
When the tooth passes through the Hall effect semiconductor sheet that flows through the current in the camshaft position sensor, the magnetic field of the sensor deflects the electron flow in the Hall effect semiconductor sheet to be perpendicular to the direction of the current, thereby causing the A voltage signal is formed, which informs the ECU that the first cylinder is exactly at the top dead center of the compression stroke.
When the camshaft position sensor fails (such as unplugging the harness plug of the camshaft position sensor), whether the diesel engine can be started successfully cannot be determined in general and should be considered based on the specific engine model. Even if the same electronic control system is used, some models can start while others cannot. This mainly depends on the control strategy of the system.
2. Camshaft position sensor failure symptoms
The main common symptoms of camshaft position sensor failure are rapid oil burning, I can’t add oil and it’s hard to beat.It is difficult to fire and start, the idle speed is unstable, the fault light is on, the vehicle can drive but the power is poor, and there will be occasional frustration during driving, which accelerates engine wear.
1. The engine is difficult to start or cannot be started, that is, the ignition fails. This is because the camshaft position sensor can predict the ignition sequence. If it fails, it will naturally be difficult to start.
2. Engine fuel consumption increases. If the camshaft position sensor fails, the trip computer will not be able to accurately inject fuel, resulting in increased fuel consumption.
3. The power is reduced and the engine is weak. If the camshaft position sensor fails, the trip computer will not be able to detect the position change of the camshaft, which will affect the intake and exhaust volumes, resulting in a decrease in power.
4. Detonation is prone to occur.
5. The engine fault light is on.
3. What are the consequences of a broken camshaft position sensor?
The camshaft position sensor is installed at the position where the camshaft rotates synchronously and provides camshaft position information. . The camshaft position sensor has a great impact on the emissions of the system. When there is a problem with the sensor, it is difficult to start the vehicle, and the acceleration will be obviously poor at startup.
If the website content violates your rights, please contact us to delete it。
