Patent ID: 6776032
Filing Date: 2004-08-17
Classification: F02D,G01M

Abstract:
A misfire deciding method for an internal combustion engine, which comprises:acquiring an internal pressure measured value based on the internal pressure of an internal combustion engine, to which a spark plug is attached, from the output of a pressure sensor mounted in a mounting seat of said spark plug; calculating the integrated value of said internal pressure measured values for a first constant integration period after an intake valve is closed and before a crank angle reaches top dead center, and setting the calculated value to a before top dead center integrated value S1; calculating the integrated value of said internal pressure measured values for a second constant integration period after said crank angle reaches top dead center and before an exhaust valve is opened, and setting the calculated value to an after top dead center integrated value S2; calculating a differential integrated value S1âˆ’S2 between said after top dead center integrated value S2 and said before top dead center integrated value S1; and calculating a first correction reference value using the internal pressure measured value at a correction measurement point set for said first integration period, to correct said differential integrated value with said first correction reference value, and making a misfire decision on the basis of the corrected differential integrated value.