| 摘要 |
On the basis of an intake air amount detected by an air flow meter (6), the upper limit-side threshold value and lower limit-side threshold value of the front-rear differential pressure of an EGR control valve (21) are calculated, and the actual front-rear differential pressure of the EGR control valve (21) is calculated from the detection values of an upstream-side pressure sensor (29) and a downstream-side pressure sensor (30). The upper limit-side threshold value and the lower limit-side threshold value, and the actual front-rear differential value are compared, and when the actual front-rear differential value is more than the upper limit-side threshold value or when the actual front-rear differential value is less than the lower limit-side threshold value, it is determined that the pressure loss of an air intake and exhaust system has changed. If it is determined that the pressure loss of the air intake and exhaust system has changed, EGR is prohibited, and if not, EGR is permitted to be performed. |
