CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

Provided is a control device, in which a maintenance control instructing to fix the opening timing (VVT) of an intake valve is executed (at instants t1 to t2) in a predetermined low load state.After this, a change control instructing to change (delay) the opening timing (VVT) by a predetermined extent is executed (at instant t2). After this, a maintenance control (at instants t2 to t3) instructing to fix the opening timing (VVT) again is executed (at instants t2 to t3). The decision that "an intake valve control device is abnormal" is made, in case the change (?ave (= ave2 - ave1)) between the average value (ave1) of many sample values of ?MFBß (the increase of the combustion ratio in a predetermined crank angle range (ß) in the expansion stroke) in the keeping control before the change control execution and the average value (ave2) of the many sample values of ?MFBß in the keeping control after the change control executions is less than a predetermined value (C).