A control system for an internal combustion engine having a variable valve operating
mechanism capable of varying at least one of a valve lift and an operation angle
of an engine valve continuously is provided. The control system comprises a detecting
device that detects an operating condition of the variable valve operating mechanism
and produces a signal representative thereof, and a controller that controls the
operating condition of the variable valve operating mechanism in response to the
signal from the detecting device. The controller is programmed to determine whether
an operation responsiveness of the variable valve operating mechanism is lowered
based on the signal from the detecting device and vary operational characteristics
of the variable valve operating mechanism when the operation responsiveness of
the variable valve operating mechanism is lowered. A control method is also provided.
