| 摘要 |
<p>Disclosed is a fault diagnosis apparatus for an airflow meter (11) for determining that the airflow meter (11) has a fault when a divergence ratio, i.e., a divergence value of an estimated intake-air quantity with respect to an actual intake-air quantity obtained by the airflow meter (11) is greater than a fault-determination reference value determined based on a rotation speed of an internal combustion engine (1). As the engine speed reduces, an upper-limit diagnosis criterion increases and a lower-limit diagnosis criterion decreases, so as to narrow an area for determining that the airflow meter has a fault. Hence, the fault diagnosis for the airflow meter (11) can be performed in the entire engine rotation speed range, i.e., in the entire operation range of the internal combustion engine (1), thus preventing a deterioration in the exhaust performance, which may occur owing to a failure in the airflow meter (11), beforehand.</p> |
