Study On The Fault Diagnosis Of Electronic Controlled Engine By Wavelet Analysis Method

The thesis introduces the advantages of the modern automobile fault diagnosis technique ,analyzes the problems of the automobile repairing industry ,analyzes the status and development of the automobile repairing industry at home or abroad , introduces the occurrence , cause and methods of the engine malfunction on the base of the common defaults.The thesis introduces the waveform analysis method and wavelet analysis method used to analyze the engine faults . The waveform analysis method can proves as a quick and precise diagnose method, wavelet analysis method can remove the noise in the signals and be the gist of estimating the engine malfunction as the supplement of the oscillo graph method.The thesis collects varieties of normal and abnormal signal waves of engine electronic control system, observes and records the malfunction phenomenon at the same time and analyzes the malfunction mechanism.Through the analysis of natural and exceptional wave shape of oxygen sensor collected by digital memory oscillo graph, the wave shape analysis method is proved exactly and fast in practice . The wavelet analysis method qua complementarity to wave shape analysis method , has function of wiping off yawp and discern character ,So it can become gist to diagnosis engine malfunction.