| 摘要 |
PURPOSE:To prevent occurrence of knocking to aim at enhancing the economy of fuel consumption and the performance of an engine, by providing a control circuit for changing a maximum value limiting the spark retarding amount in accordance with a variation in the air-fuel ratio which is controlled by an air-fuel ratio control means. CONSTITUTION:An air-flowmeter 10 is disposed downstream of an air cleaner. The air flowmeter 10, an intake-air temperature sensor 12, a throttle sensor 24A, a knocking sensor 36, a cylinder discriminating sensor 46, a rotating angle sensor 48, a cooling water temperature sensor and an exhaust gas temperature sensor 50 are connected to a control circuit 45. An ignitor 44 and a fuel injection valve 26 are controlled in accordance with a control signal delivered from the control circuit 45. When it is discriminated that temperature of exhaust gas is below a predetermined value, a maximum value for limiting the spark retarding amount is increased by a constant value. Further, the compensation spark retarding amount is limited to such a maximum value so that a value which obtained by subtracting the compensating spark retarding amount from a basic spark advancing amount is used as an executive spark advance. With this arrangement, it is possible to prevent occurrence of knocking, thereby it is possible to aim at preventing an engine from being damaged, and at enhancing the economy of fuel consumption and performance of the engine. |
