| 摘要 |
PROBLEM TO BE SOLVED: To precisely determine the failure of a cylinder internal pressure sensor in a wide operation range and concurrently to attain high determination precision even when performing air-fuel ratio control.SOLUTION: An ECU50 calculates maximum cylinder internal pressure Pmax affected by output sensitivity of a cylinder internal pressure sensor 44 and the center of gravity of combustion CA50 which is a combustion timing index T not affected by the output sensitivity based on only the output of the sensor. Abnormality of the output sensitivity is detected based on a ratio A between a Pmax estimated value which is the maximum cylinder internal pressure calculated based on the center of gravity of combustion CA50 and a detected Pmax value which is an actually obtained maximum cylinder internal pressure. As a result, the abnormality of the sensitivity is detected based on only the output of the cylinder internal pressure sensor 44 in a wide operation range. The high detection precision is attained even when air-fuel ratio control is executed by avoiding the phenomenon where the combustion timing index T is kept at a fixed value by the air-fuel ratio control. |
