Misfire detection based on engine speed using wavelet

Misfire detection is an important part of on-board diagnostics (OBD) system which is widely used at present. There are several methods to detect misfire, and the method of misfire detection based on engine speed is the most popular one, even though it cannot detect misfire very well when engine speed is high. An improvement to the method of misfire detection based on engine speed using wavelet algorithm is presented in this paper, and it is validated on a high speed four cycle engine. The test results show that the improved method can detect misfire accurately even when the engine speed is very high.