Apparatus and method for detecting abnormalities in a secondary air supplier

摘要

Disclosed is an apparatus for detecting abnormality in a secondary air supplier of an engine. The operational status of the engine is monitored by various sensors. When the engine is in a warmed-up state, an electronic control unit (ECU) disables the secondary air supplier to stop secondary air from being supplied to an exhaust manifold. When the engine is in such an operational status in which the secondary air should be supplied, the secondary air supplier is activated and a fuel supplying means is controlled in such a way that a suction air-fuel ratio is forcibly adjusted to a predetermined high value so as to set an exhaust air-fuel ratio low when the secondary air supplier functions properly and set the exhaust air-fuel ratio high when the secondary air supplier is abnormal. When the exhaust air-fuel ratio is detected to be high, the ECU judges the secondary air supplier as abnormal and executes necessary processing, such as outputting an abnormality judgment signal to an external warning device.