SECONDARY AIR SYSTEM DIAGNOSTIC TEST

摘要

A diagnostic test for a secondary air system comprising an air pump, a first mass air flow sensor connected to the air pump and a first check valve connected to the first mass air flow sensor. A first testing phase is disclosed comprising a first delay period and a first testing period, wherein the air pump is activated. A second testing phase is disclosed comprising a second delay period and a second testing period wherein the first check valve is opened. A third testing phase comprising a third delay period and a third testing period is disclosed wherein the first check valve is closed. A fourth testing phase is disclosed comprising a fourth delay period and a fourth testing period wherein the air pump is deactivated. An optional fifth testing phase is also disclosed comprising a fifth delay period and a fifth testing period wherein the air pump remains off but the check valve is reopened and engine RPMs are increased. The diagnostic test further includes determining one or more failure modes of the system based on the output from the four or five testing phases.