Maintenance method and fault case analysis of injector

(1) injector structure: the injector is installed on the intake pipe of each cylinder, 70~ 100mm away from the center line of the intake valve, and the spray shape is 25 conical. The structure of the fuel injector is as follows: Figure Structure of the fuel injector There are two O-ring seals on the fuel injector, and the lower seal ring is located between the fuel injector and the air inlet. The lubricating sealing ring must be replaced every time the fuel injector is removed. O-ring has the function of heat insulation, which can prevent fuel from forming air lock in the injector, thus improving the hot start performance and preventing the injector from generating excessive vibration. The upper sealing ring is used to ensure the seal between the fuel injector and the fuel manifold. The fuel pressure is 250~350kPa, and the electromagnetic coil impedance is 12.2. (2) Disassemble the fuel injector: When disassembling the fuel injector, the conductive pin and the fuel injection hole in the connector must be prevented from being damaged. The fuel injector assembly cannot be cleaned with any cleaning agent. When removing, secure the fuel manifold to prevent damage to other components. You must use the same model and the same flow syringe for replacement. Disassembly steps are as follows: [1] Release the fuel system pressure. [2] Remove the intake manifold. [3] Remove the electrical connector and fuel manifold. [4] Remove the retaining clip and remove the fuel injection pipe from the fuel manifold. [5] During installation, it must be disassembled in the reverse order and replaced with a new O-ring. Maintenance method of fuel injector: (1) Check the fuel injector in the car. The steps are as follows: [1] When the engine is running, it is normal for fingers to feel vibration on the fuel injector. [2] When the engine is running, unplug the control line plug of the cylinder injector. If the engine speed drops or is unstable, it means that the injection of the cylinder works normally; Otherwise, the injector of this cylinder is not working properly. [3] As shown in figure 1-80, check the resistance of the electromagnetic coil of the fuel injector. Low-resistance fuel injection should be detected by high-precision digital multimeter. The resistance of cold start injector is 2~5, the resistance of low resistance injector is 1.5~3, and the resistance of high resistance main injector is about 13. The coil must not be short-circuited, open-circuited or grounded, otherwise it should be replaced. Figure Check the resistance of the solenoid coil of the fuel injector. (2) Fuel injection test: [1] spray test. Remove the fuel injector, connect the fuel supply pipe to the battery or connect a 3V power supply, and touch the positive electrode of the battery with wires. It is normal to simply inject oil and stop oil in time. [2] Oil drop test. When the fuel injector is not energized, but the electric fuel pump continues to pump oil, it is normal for the fuel injector to drop more than 1 drop per minute. [3] The fuel injection quantity test of the fuel injector is shown in the figure. Connect the fuel injector to the battery15s, and check the fuel quantity injected. Each model has specific requirements, so you should consult relevant information. Check the fuel injection quantity difference of all fuel injectors. Generally, 15s should not be greater than 5mL. Fig. Fuel injection quantity test of injector. [4] Simple inspection method. Two dry cells (about 3V) can be connected to the fuel injector to blow air into the fuel injector. If there is no electricity, it will not blow, and it will be normal if there is no leakage; It can fuse normally after being electrified. Example of fuel injector maintenance 1: model: Fukang AL. (1) Fault symptoms: the idle speed is unstable, the engine speed fluctuates between 700 and 800 r/min, the engine is turned off in the cold state, and the engine power is insufficient during driving. (2) The cause of the failure is that the fuel is not clean, which leads to the gel of the fuel injector, insufficient fuel injection and incorrect air-fuel ratio, which leads to unstable idle speed and insufficient engine power. (3) Diagnosis and elimination method: [1] Computer detection with specific concentration can automatically adapt to temporary faults. [2] Clean the idle rotating valve body, intake pressure sensor and pipeline. [3] Check whether the ignition time is normal. The effect of replacing 93# gasoline with 4 is not obvious. [5] Check that the fuel system pressure is 250kPa, which is normal. [6] Check whether the fuel injector is too dirty, and the vehicle returns to normal after cleaning. Example 2 of fuel injector maintenance: Model: Fukang 988. (1) Fault symptom: The vehicle is running normally. When the vehicle stops for more than 10 minutes, it is difficult to start the engine. The engine can only be started by increasing the throttle opening. (2) The cause of the failure is that the fuel injector is poorly sealed and gasoline leaks into the cylinder. (3) Troubleshooting: After replacing the fuel injector sealing ring, the engine works normally. Example 3 of fuel injector maintenance: (1) Fault symptoms: insufficient engine power, poor acceleration and unstable idle speed. (2) Fault diagnosis: [1] use V.A.G.1552 scanning tool to query the trouble-free code storage. [2] Check whether the idle HC exceeds the standard. [3] Check whether the spark plug works normally. [4] Disassemble the fuel injector for inspection, and it is found that two cylinders have poor fuel injection. (3) After cleaning the injector, the engine works normally. Fuel injector maintenance example 4: Model: Jetta GT. (1) Fault symptom: engine idling jitter. (2) Fault diagnosis: [1] use V.A.G.1552 scanning tool to query the trouble-free code storage. [2] The inspection found that one cylinder injector was poorly sealed. (3) Troubleshooting: After replacing the fuel injector sealing ring, the engine works normally. Example 5 of fuel injector maintenance: Model: Jetta GTX. (1) Fault symptom: poor engine acceleration. (2) Fault diagnosis: [1] use V.A.G.1552 scanning tool to query the trouble-free code storage. [2] Check whether the idle exhaust gas is normal. [3] The inspection found that the wire from the fuel injector to the ECU was worn, and the fuel injection of the fuel injector was out of control.