| 摘要 |
PURPOSE:To prevent change of operatability of a malfunctioned internal combustion engine and increase of concentration of poisonous element in exhaust gas by forcibly opening an EGR valve at the time of fuel supply stoppage when self-diagnosis of an exhaust gas re-circulating device is performed. CONSTITUTION:When a vehicle is driven, and a condition for stopping of fuel supply at the time of deceleration is established at a CPU 51, it is judged whether the condition is a fuel supply stopping delay period until the start of the fuel supply stopping or not. When the answer is NO, it is judged whether the fuel supplying stoppage at the time pf deceleration is carried out or not. When the fuel supply stoppage is carried out, electricity is applied to a solenoid control valve 45, a port a is connected to a port c, and a comparative large negative pressure in an intake pipe of a surge tank 3 is introduced in a diaphragm chamber 27 of an EGR valve 20 to forcibly open the EGR valve. An intake pipe pressure detected by an intake pipe pressure sensor 58 is taken both at the time that the EGR valve is forcibly opened and not opened. The malfunction of the EGR device is judged when the difference between the intake pipe pressure is a specified value or smaller. |
