The fuel injector is a key part of the engine. It is a kind of precision device with very high machining accuracy. It requires a large dynamic flow range, strong anti-blocking and anti-pollution ability and good atomization performance.The injector receives the fuel injection pulse signal sent by ECU and accurately controls the fuel injection quantity. The quality of its work directly affects the power performance, economy, emission and reliability of the engine.
According to the requirements of mixture formation and combustion, the injector should have certain injection pressure, injection stroke, and appropriate injection cone Angle. In addition, the injector should be able to cut off fuel supply quickly when it is necessary to stop injection, without oil dripping.
The common faults of fuel injectors include mechanical faults and electrical faults.Mechanical faults include fuel injector spool stuck, fuel injector blocking and leakage. When the fuel injector appears above, it will cause mechanical action failure, thus affecting the normal operation of the engine, and sometimes even make the engine appear serious failure.
The work of the injector is the signal sent by the engine control unit. The electromagnetic coil of the injector is energized and the suction is generated to drive the needle valve of the injector.Because the gap between the needle valve and the valve seat is blocked by the residual adhesive, the needle valve action is astringent and can not be opened normally, thus affecting the normal amount of injection.
The injector needle valve stuck after the failure, the engine will appear difficult to start, idle instability, poor acceleration and other symptoms.The main reason for the injector stuck is the use of inferior diesel oil, because the paraffin and gum in inferior diesel oil, which leads to the injector needle valve stuck.
Injector blocking faults can be divided into internal blocking of the injector and external blocking of the injector head.Injector internal blockage is caused by impurities and dirt mixed with diesel fuel to block the movement gap of the needle valve inside the injector, so that the mechanical action of the injector is abnormal.
When the injector blocking fault, the engine will appear the corresponding start difficulty, idle instability, poor acceleration and other symptoms, the serious situation will even cause serious engine jitter, and cause the occurrence of abnormal wear of the relevant mechanical components.
Injector leakage fault is generally divided into internal leakage and external leakage of two cases.The internal leakage of the injector is mostly caused by its early wear in use, which causes it to leak fuel into the intake manifold under the action of system pressure.
The external leakage of the injector mostly occurs at the junction of the injector and the oil rail, and the sealing surface is not tight.If diesel leakage in the intake manifold outside, oil drops on the cylinder block, heat will evaporate in the engine cabin, once there is an electric spark, will cause fire at any time, the consequences are very serious.
When the internal leakage of the injector occurs, it will cause poor atomization of the fuel ejected by the injector, resulting in unstable engine operation, incomplete combustion of the mixture, black smoke from the exhaust pipe, and will lead to a significant increase in fuel consumption of the vehicle.
When the injector external leakage fault occurs, it will lead to engine starting difficulty, idle flout, power decline, fuel consumption increase, operation surge and poor acceleration and other faults.In addition, when the sealing surface of the connection between the injector and the intake pipe is damaged, it will also lead to the leakage of the intake system, resulting in extra air entering the engine combustion chamber, resulting in thin mixture and abnormal engine operation.
When the needle valve couple is seriously worn or the needle valve body and the injector shell is not tight enough, the oil return of the injector increases significantly. At the same time, attention should be paid to the valve plate, which once worn will lead to the oil return of the injector is too large, affecting the engine performance.The injection pressure is reduced, the injection time is delayed, the engine power is reduced, and even the engine flameout is caused.
Note: It should be pointed out that the common rail system belongs to high pressure system, so please do not disassemble without authorization to avoid damage. The fuel injector belongs to precision parts, so please choose professional maintenance points for repair, and choose professional maintenance tools for disassembly.
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