With the rapid development of China's automobile industry, the pollution of the automobile exhaust to the environment is becoming more and more serious. To this end, the state has established strict emission standards. In the field of diesel engines, various manufacturers are constantly adopting new technologies to optimize diesel engine performance, improve fuel economy and reduce diesel engine emissions. The electronic control of diesel engines is the core of these new technologies. It detects the state of the diesel engine through various sensors, and the electronic control module processes it quickly, precisely controlling the fuel injection amount and fuel injection timing of the injector and the fuel pressure in the high-pressure fuel rail to achieve optimal fuel metering and injection. In view of the structural characteristics of Cummins L series electronically controlled diesel engine, this paper introduces the precautions and scientific troubleshooting methods for electronically controlled diesel engine fault diagnosis.
L series electronically controlled diesel engine
Cummins L series electronically controlled diesel engine
Use criteria
Before repairing the L series electronically controlled diesel engine, the service personnel must obtain the L series electronically controlled diesel engine service qualification certification, and grasp the mechanical structure, working principle, maintenance and operation of the L series electronically controlled diesel engine. Operation and use of the L-Series electronically controlled diesel engine must comply with the following guidelines for use:
1) The steps of powering on and off the L series electronically controlled diesel engine are: when powering on, first turn on the main switch of the vehicle, then turn the key switch to the ignition position; when turning off the power, first turn the key switch to the “off†position ( OFF position), after turning off the main power supply after 30s, the electronic control module must first execute the shutdown procedure. If the power is not turned on and off in the above order, fault code 1117 will be generated, and some data or even programs stored in the electronic control module may be destroyed, causing some other faults.
2) It is not allowed to disassemble or install the electronic control module connector, sensor connector and actuator connector when the electronic control module is working (ie the ignition key is in the "ON" position). Electronic control modules, sensors and actuators are all electronic components. Inductive components generate high voltage due to self-inductance at the moment of electrification disconnection or switching-on, which may damage some semiconductor components or integrated circuits or even ablate contacts. Cause damage to the electronic control module, sensor or actuator.
3) When performing electric welding on the vehicle equipped with L series electronically controlled diesel engine, all the plugs on the electronic control module should be removed and the main switch should be disconnected. It is strictly forbidden to carry out the welding work under the condition that the electronic control module is energized. In the early days when the L series electronically controlled diesel engines were introduced to the market, some automakers performed electric welding operations without the diesel engine being powered off. As a result, many diesel engines failed, including the power module being quickly broken down, locked up or procedurally circumvented. The diesel engine cannot start and other problems.
4) Do not flush the L series electronically controlled diesel engine directly with water. Wipe the engine's electronic control section with a damp cloth or clean the diesel engine with compressed air. The electrical plugs of diesel engines are equipped with multi-ring seals to prevent water and moisture from entering, but water with a certain pressure will pass through the seal ring and enter the inside of the electrical plug, which will cause signal distortion, abnormal operation of the diesel engine or inability to work. This causes damage to electrical components and even electronic control modules.
5) All plugs on the electronic control module must be installed after connecting the positive and negative terminals of the battery. This is to prevent damage to electrical components caused by operational errors during vehicle assembly or during vehicle modification. For example, when the main switch is turned on, connecting the positive and negative poles of the battery will damage the electronic control module due to ignition.
6) All plugs on the L series electronically controlled diesel engine must be checked for foreign objects, moisture, rust and damage before installation. Make sure that the plugs are installed in place, the connection is secure, and the locking tabs are locked in place during installation. Improper installation may damage the electronic control module.
7) Take measures against magnetic fields and anti-interference. There is a ground wire on the outer casing of the electric control module, which must be ensured that it is well grounded with the cylinder block. Failure to connect the iron wire will cause the electronic control module housing to be static and work poorly, and the engine will run violently. Shielded wire for throttle pedal line and twisted pair for injector circuit. It must be installed in strict accordance with the "L series electronically controlled diesel engine electrical installation manual".
8) The fuel system has high requirements for cleanliness. Impurities such as dirt, dust and water can directly cause damage to the high pressure oil pump and injector. When repairing and maintaining the fuel system, the surrounding area of ​​the open area must be cleaned. If the disconnected joint is not installed immediately, it must be closed with a special plastic plug or plastic cap. When the engine is just off, the high pressure common rail fuel pipe still maintains a high pressure, and the high pressure fuel pipe joint can be removed after the engine is turned off for 10 minutes. It is forbidden to deflate the fuel system on a hot diesel engine.
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