| 摘要 |
In the present invention, the deviation value is calculated between an actual air excess ratio, which is calculated from the oxygen concentration value of an NOx sensor provided downstream of an exhaust gas purification device provided to an exhaust pathway, and a target air excess ratio, which is calculated from the current designated amount of fuel injection and the amount of new air detected by an MAF sensor provided to an intake pathway, the result is recorded at a learning region map (M1) having the common rail pressure and designated amount of fuel injection as a base, the current learning value corresponding to the currently designated amount of fuel injection and the current common rail pressure is corrected in a manner so that the deviation value becomes zero, a new learning value is calculated, the currently designated amount of fuel injection is corrected by means of the learning value at the time of fuel injection from an injector, fuel injection is performed, and when the absolute value of the learning value has become greater than a pre-set abnormality determination value, it is determined that the fuel injection is abnormal, by which means, using an NOx sensor, abnormality in fuel injection is detected when correcting in a manner so that the deviation between the designated amount of fuel injection and the actual amount of fuel injection resulting from injector degradation or the like becomes zero. |
