Intake system failure diagnosis apparatus for automotive internal combustion engine

摘要

PROBLEM TO BE SOLVED: To provide an intake system failure diagnostic device of an on-vehicle internal combustion engine, capable of further highly reliably diagnosing failure of an intake system from the relationship between the air volume sucked in a combustion chamber and the suction air volume measured by an air flowmeter.;SOLUTION: An electronic control device of the on-vehicle internal combustion engine diagnoses the effect of being "intake leakage failure" under a condition that a difference quantity of an air-fuel ratio learning value being a learning value of a feedback correction factor in air-fuel ration control is large in an engine idle operation area and small in an engine high load operation area, and being "air flowmeter failure" under a condition of indicating an equal tendency in these respective operation areas, when the suction air volume measured by the air flowmeter is smaller by a predetermined value q4 or more than an ISC basic flow rate being the theoretical valued air volume sucked in a combustion chamber at a target idle rotating speed, when an ISC learning value being a learning value of a correction quantity of throttle opening in ISC control is less than a predetermined value q1.;COPYRIGHT: (C)2010,JPO&INPIT