| 摘要 |
PROBLEM TO BE SOLVED: To provide a combustion diagnostic method and a combustion diagnostic device of an internal combustion engine capable of clearly identifying and determining preignition and abnormality of a pressure sensor in a cylinder, and with heightened reliability by detecting preignition in a cylinder in a wide load range regardless of an operating condition. SOLUTION: In this combustion diagnosis method of an internal combustion engine (engine) for diagnosing a combustion condition in a cylinder based on an in-cylinder pressure detection value detected by an in-cylinder pressure detector, preignition is determined when a standard deviationσP<SB>α</SB>of a change of the in-cylinder pressure at a predetermined crank angleαbefore ignition of the engine is calculated and the standard deviationσP<SB>α</SB>is not less than a standard deviation threshold valueβ, and when a differential pressureΔP<SB>0</SB>of the in-cylinder pressures at a reference crank angle and a top dead center is calculated and a load factor in-cylinder differential pressureΔP<SB>0</SB>/L found by dividing the differential pressureΔP<SB>0</SB>with a load factor L on a driven machine driven by the engine is not less than a load factor in-cylinder differential pressure threshold valueγ. COPYRIGHT: (C)2009,JPO&INPIT
|
