Intake air quantity control apparatus and method for an internal combustion engine

An intake air quantity control apparatus for an internal combustion engine comprises: a Offungssteuermechanismus and a variable valve mechanism that controls an intake air amount; an intake characteristics change mechanism for controlling the intake air quantity by setting a parameter or parameters of which differ from those of the above-mentioned two mechanisms; and an intake quantity control device for performing cooperative control of these mechanisms upon the occurrence of any of a normal state. The intake-air quantity control apparatus further includes: an abnormality detecting device for detecting an abnormal condition in these three mechanisms; and a fail-safe device for controlling the intake air amount of Offnungssteuermechanismusses besides these three mechanisms and for controlling the other two mechanisms, so as to fix the control variables at constant values.