Patent ID: 6457353
Filing Date: 2002-10-01
Classification: F01L,F02D,Y02T

Abstract:
An apparatus of diagnosing an internal combustion engine having a variable valve mechanism and in which an intake valve or an exhaust valve sequentially opens and closes each of a plurality of cylinders of said internal combustion engine by electric signals, comprisingan input means for indicating an operating condition of the variable valve mechanism, and an air flow meter based upon operational differences among the cylinders operatively associated with said input means and configured to directly detect a fluctuation of backward flow as an amount of mass air flow to diagnose an abnormality in said variable valve mechanism and a control apparatus of said variable valve mechanism is in accordance with said quantity of the backward flow which flows into an intake manifold of the internal combustion engine and with an overlap open time period when neither the intake valve of the exhaust valve are closed.