| 摘要 |
PURPOSE:To prevent a mistaken diagnosis caused by an exhaust gas temperature by judging the abnormality of EGR based on the difference between an EGR passage temperature at the time of carrying out EGR for more than a defined time and the EGR passage temperature at the time of carrying out more than a defined quantity of EGR for more than a defined time. CONSTITUTION:The detected values of an air flow meter 6, an exhaust gas temperature sensor 17 provided in an EGR passage 8, an intake air temperature sensor 19, a throttle switch 21, a water temperature sensor 22, a vehicle speed sensor 25, an engine speed sensor 26, etc. are inputted into a control circuit 10. The control circuit 10 carries out EGR at a cooling water temperature of approx. 60 deg.C, or above, at an intake air temperature of 0 deg.C or above, and except at the time of idling and a full load, and measures the temperature of the EGR passage 8 when the value of counting which is counted up in an EGR zone or counted down in a non-EGR zone becomes a defined value. And, by equally measuring the temperature of the EGR passage 8 when the value of counting of more than a defined quantity of the EGR zone becomes a defined value, the abnormality of the EGR is judged based on the difference in both temperatures. |
