| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that it cannot accurately distinguish whether the cause of a misfire is conventionally resulting form deterioration in a spark plug or from other separate reasons when determining the existence of the misfire. Ž<P>SOLUTION: This method for determining the deterioration state of the spark plug includes a fist step of detecting an air-fuel ratio and pressure in a combustion in individual ignition, a second step of determining the existence of the occurrence of the misfire in the individual ignition, a third step of determining a misfire probability at individual ignition with the air-fuel ratio and the pressure in the combustion chamber as a variable by repeating these first and second steps, a fourth step of setting a reference misfire probability at the individual ignition with the air-fuel ratio and the pressure in the combustion chamber as the variable, and a fifth step of determining the deterioration state of the spark plug based on the reference misfire probability set by the fourth step and the misfire probability determined by the third step. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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