FAILURE DIAGNOSTIC DEVICE FOR AUXILIARY AIR QUANTITY CONTROL VALVE

摘要

PURPOSE:To judge the operational state of an auxiliary air quantity control valve invariably correctly by concurrently using change quantities of the intake air and engine rotating speed when the control output value of the auxiliary air quantity control valve is changed as failure judging parameters. CONSTITUTION:The control signal for controlling the auxiliary air quantity control valve of an engine is outputted from an output means 1. The rotating speed of the engine is detected by a detecting means 2, and the intake air quantity of the engine is detected by a detecting means 3. The difference between the first and second engine rotating speeds when the first and second control values are used as control signals is compared with the first reference value by the first comparing means 4. The difference between the first and second intake air quantities when the first and second control values are used as control signals is compared with the second reference value by the second comparing means 5. The failure of the auxiliary air quantity control valve is judged by a judging means 6 based on outputs of the comparing means 4, 5.