Apparatus and method for detecting abnormality of air flow meter

摘要

An apparatus for detecting an abnormality of an air flow meter (43) is disclosed. The flow meter (43) is disposed in an air intake passage (20) of an engine (10) to detect an actual flow rate of air flowing through the air intake passage (20). The air intake passage (20) has a throttle valve (22) with a variable opening size (TA) to control the actual rate of the air flowing in the air intake passage (20). The throttle valve (22) adjusts the actual flow rate of the air according to an engine speed (NE) when the opening size (TA) is in a first range, and regardless of the engine speed (NE) when the opening size (TA) is in a second range. A throttle sensor (44) detects the opening size (TA) of the throttle valve (22). An ECU (50) computes a target rate of the air flowing in the air intake passage (20) based on the detected opening size (TA) of the throttle valve (22), and a marginal range for allowing a deviation of the actual rate of the air flow from the target rate. The ECU (50) determines the abnormality of the air flow meter (43) when the opening size (TA) of the throttle valve (22) is in the second range and the actual rate of the air is out of the marginal range.