| 摘要 |
An upper-limit threshold value and a lower-limit threshold value of a fore-and-aft differential pressure of an EGR control valve (21) is calculated based on an intake-air quantity detected by an airflow meter (6). An actual fore-and-aft differential pressure of the EGR control valve (21) is calculated from detected values of an upstream-side pressure sensor (29) and a downstream-side pressure sensor (30). Then, the upper-limit threshold value and the lower-limit threshold value are compared with the actual fore-and-aft differential pressure, and when the actual fore-and-aft differential pressure exceeds the upper-limit threshold value or when the actual fore-and-aft differential pressure is less than the lower-limit threshold value, it is determined that the pressure loss of an intake and exhaust system has changed. If it is determined that the pressure loss of an intake and exhaust system has changed, EGR is inhibited, and if not so, EGR is permitted to be performed. |
