Fault diagnostic system for internal combustion engine and fault diagnostic method for internal combustion engine

摘要

A learning unit learns a difference between a detected value ECT and a detected value RCT when it is determined that the detected value ECT and detected value RCT are stable while an engine is at a stop. A diagnostic unit performs a fault diagnosis for the engine based on the difference between the detected value ECT and detected value RCT having been corrected through use of a learned value learned by the learning unit. Accordingly, a fault diagnostic system for an internal combustion engine and a fault diagnostic method for an internal combustion engine can be achieved in which accuracy in fault diagnosis for the internal combustion engine can be improved and an erroneous diagnosis can be restrained.

主权项

1. A fault diagnostic system for an internal combustion engine,
the internal combustion engine including a cooling device having a radiator and a cooling water passage configured to circulate cooling water between the internal combustion engine and the radiator, the fault diagnostic system comprising: a first cooling water temperature sensor configured to detect a temperature of cooling water flowing in the internal combustion engine through the cooling water passage; a second cooling water temperature sensor configured to detect a temperature of cooling water flowing in the radiator through the cooling water passage; and a processor configured to: learn a first temperature difference between a detected value of the first cooling water temperature sensor and a detected value of the second cooling water temperature sensor at a first time when it is determined that the detected values of the first and second cooling water temperature sensors are stable while the internal combustion engine is at a stop; at a second time after the first time, determine a corrected temperature difference between a water temperature detected by the first cooling water temperature sensor and a water temperature detected by the second cooling water temperature sensor, wherein the corrected temperature difference is determined through use of the first temperature difference; and perform a fault diagnosis for the internal combustion engine based on the corrected temperature difference.