Practical Research In The Detection And Diagnosis Of Faults In Electronic Control Fuel Injection Engine Emissions

Electronically controlled engine has become the main resource of automobile power because of its superiority in lower pollution emissions and energy consumption. Owning to its different controlling principle to the carburetor petrol engine and its various types, the fault diagnosis of electronically controlled engine has become the main problem facing before the automobile maintenance industry. Because of the technology limitation, there is some difficulty to diagnose all engine fault with the method and tool in existence. As one part of the vehicle checking and measuring, emission examining has become a criterion. The emission ingredients can reflect the working condition of fuel supplying system and air supplying system, the mixing and burning condition in cylinder. This test simulated the different faults, checking and analyzing the emission ingredients in lab. Through studying the different emission characteristic, the aim is to find a way that can integrate the presented diagnosing tools and emission analysis, and diagnose the faults quickly and exactly.This paper discusses the working principle, application actuality, the building and checking mechanism of exhaust emissions of EFI engine. It analyses the present situation and the problem existing in fields of vehicle maintenance. The influence of the malfunction of the air supplying system, fuel supplying system and common sensors that can not be diagnosed by self-diagnosing system to engine emissions are analyzed especially. At the same time, the paper introduces the structure and the principle of some sensors and actuators in air supplying system and fuel supplying system, and the method of using exhaust-gas analyzer to check and measure the malfunction locality. In the end, the paper discusses the working principle and simple applications of the method of waveform analysis and wavelet analysis.The main work and result is as follows:1. Emission analysis and the flow chart for electrically controlled engine fault diagnosis have been brought forward after analyzing the working principle of the engine and the building mechanism of exhaust emissions.2. Here the jam of the fuel pipeline, the air supplying system leaking, air flowsensor's weaken fault, no burning in cylinder, and speed sensor's weaken fault have been analyzed emphatically. The method to diagnose the fault above through emission analysis has been put forward.3. By simulating the starting failure, the method to diagnose the faults of no speed signal, no sparking, no fuel injecting, and lower pressure of fuel supplying system through emission analysis has been acquired.