Wave Pattern Analyses And Fault Diagnoses Of 4g18(1.6l) Gas Engine Electric Control System

With the development of automobile technology, especially rapid development and application of electric control system(ESC) in automobile. It requests faulty diagnosis of automobile to develop into a new hi-tech. The instrument used for automobile technology faulty diagnosis is developed several phases—from simple compass avometer, digital avometer, decoder, scanner to automobile oscilloscope. Wave pattern of ECS's each component in automobile engine can be used to detect and diagnose the ECS. It has great importance to apply wave analysis and fault diagnosis technology for automobile engine ECS.This paper chooses the representative Dongan Mitsubishi4G18(1.6L) engine ECS as the research object to analogue and set up fault of ECS in automobile. Using Fluke98's special oscilloscope analyzes wave and diagnoses fault. The study shows:1. Ignite secondary wave, primary wave and ignite timing signal wave can provide valuable data about each air cylinder ignition and combustion status. Ignition WP is affected by different engines, fuel system and ignition. The measured wave shape is right or not, thickness or length of the lines, the size of data and stability are related each other with engine, combustion system and ignition system parts. So ignition wave shape can efficiently detect the faults of engine combustion and ignition system.2. 4G18 engine Mitsubishi's ECS sensor mainly include: MAP, TPS, DS, TS, CPS, CIS and VSS. Sensor is important for the ECS, especially when sensor signal of CPS is malfunction, the whole ECS will be in a paralyzed status. When ECU control is neither ignite nor inject oil, the engine can't work. When signal wave pattern of PS is abnormal, ECU control inject oil is not completed before inlet air is open. If compressor cylinder cant judge, explosion vibration will stop and influence engine's whole function very little. When other senor signal is abnormal, it will influence the amount of inject oil differently. Therefore, it is the key for modern automobile ECS's maintenance to faults diagnosis, check and maintenance of sensor. It is an efficient way to use oscilloscope to check output signal wave of sensor, this can diagnose the faults and maintenance of sensor.3. 4G18 engine Mitsubishi's ECS performer mainly includes: Injector, Idle step motor, carbon pot control valve and EGRV. Performer is responsible for results of engine ECU output control directions. If performer is malfunction, engine electronic control will not be carried out. If injector control signal is malfunction, the engine can't work. Whether wave pattern of idle step motor is normal or not, it will affect highness of idle. Especially when it is malfunction, the engine is in an emergency way to make idle high. Whether carbon pot control valve and EGRV is normal or not, it will directly affect releasing. To check wave shape of performer is an efficient way to diagnose faults.4. OS is the essential part of fuel feedback control system. According to signal voltage wave shape of OS, it can reflect inlet air system, combustion injection, ignite status of engine. Whether it is normal or not, it can wholly diagnose fault of engine ECS. We can combine OS's wave shape with width of injection pulse to analyze the cause of exhaust faults. The wave shape of OS is very sensitive and easily disturbed. So after repairing automobile, if the wave shape of OS is in a good condition, that is to say, the maintenance of automobile is successful.