Diesel engine oil injection timing fault diagnosis method based on rail pressure signal

The invention discloses a diesel engine fuel injection timing fault diagnosis method based on a rail pressure signal. The method comprises the following steps that whether a vehicle runs in a braking or sliding state or whether a vehicle engine runs under a stable working condition is judged; oil supply of the high-pressure oil pump is cut off, and reference oil injection timing and reference oil injection quantity are preset; crankshaft phase angle data and rail pressure signal data with timestamps are collected; judging whether complete working cycle data of the engine is collected or whether the condition of recovering oil supply of the high-pressure oil pump is met; oil supply of the high-pressure oil pump is recovered, and preset reference oil injection timing and reference oil injection quantity are cancelled; a Savitzky-Golay filtering method is adopted for conducting filtering and derivation calculation on the rail pressure signal data, according to crankshaft phase angle data, the actual fuel injecti