Abstract:Insufficient driving force is one of malfunctions that frequently occurs for engines, Due to complicated causes and overloading conditions, it is a difficult point in engine malfunction diagnoses. Based on the engine control principle, from a new visual angle, four kinds of causes of insufficient engine driving force are discussed, the variations of mixture characteristic values and the ignition angles in the fault conditions are obtained, together with a relationship among five parameters in fault conditions, including the injection time of each turn, which increases the correlation of these parameters greatly, and enhances their applicability in fault diagnosis. Based on this method, the locations may be identified where failure may occur.