Apparatus and method for detecting abnormality of air flow meter

摘要

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