| 摘要 |
PURPOSE:To perform accurate detection of sensor fail, even when a noise level for creating a knocking decision level is decreased, by deciding the sensor fail in the second predetermined period of engine vibration as compared with the first predetermined period for detecting the noise level. CONSTITUTION:In a gate for sensor fail, a period of increasing vibration noise, for instance, a period, where an influence of valve seating vibration or the like appears in an output signal of a vibration sensor 1 despite presence of knocking, is set, and in a microcomputer 5 during engine operation, first in the gate for the sensor fail, a level for sensor fail is calculated in accordance with a result of checking whether an output of a comparator 3, that is, noise pulse is provided or not. Next by comparing a sensor fail deciding level with a sensor fail decision value, a number of continuously decided times is counted when the sensor fail deciding level is smaller than the sensor fail decision value. In the case of deciding a counted valve larger than a predetermined decision value, the sensor fail is decided. |
