| 摘要 |
PURPOSE: A diagnosing method of a defect in a thermostat for a vehicle is provided to diagnose the defect of the thermostat by detecting a caloric value of an engine and an intake air amount of a cylinder in a real time. CONSTITUTION: A temperature of coolant is detected. The detected coolant temperature is compared with a monitoring area. A cycle is returned when the coolant temperature is over the monitoring area. Otherwise, the coolant temperature is detected in a real time. Accumulated data of an intake air amount in a cylinder is stored. The cycle is returned to the detection of the real time coolant temperature when the real time coolant temperature is raised over a unit temperature. Otherwise, a gradient value of the stored intake air amount in the increase of each unit temperature of the coolant temperature is calculated. A thermostat is diagnosed as a defect when the gradient value of the intake air amount is over a set boundary value. Otherwise, the coolant temperature is compared with the monitoring area. The thermostat is diagnosed as normal when the coolant temperature is over the monitoring area. Thereby, the defect of the thermostat is diagnosed exactly.
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