Engine control system

An engine control system for controlling an internal combustion engine equipped with a variable valve timing mechanism which alters intake valve duration, measured in degrees of engine crankshaft rotation, that an intake valve remains open, and one fuel injector for each cylinder in the engine which injects fuel into an intake manifold of the engine, said engine control system comprising:

• fuel injection control means for causing said fuel injector to perform a plurality of times of fuel injection to deliver a total amount of fuel necessary every engine cycle into said intake manifold, said fuel injection including leading fuel injection terminating while an intake valve in said cylinder remains closed and trailing fuel injection terminating at a predetermined time in an intake cycle;
• engine operating condition detecting means for detecting operating conditions of said engine;
• fuel amount computing means for computing a total amount of fuel to be injected every engine cycle on the basis of engine operating conditions detected by said engine operating condition detecting means before said leading fuel injection, for computing a leading injection amount of fuel to be injected for a duration of time of said leading fuel injection, for computing a difference of an updated total amount of fuel to be injected every engine cycle, which is computed on the basis of engine operating conditions detected, after termination of said duration of time of said leading injection, by said engine operating condition detecting means, from said leading injection amount of fuel as a trailing injection amount of fuel to be injected for a duration of time of said trailing fuel injection;
• and
• duration ratio control means for controlling a relative ratio between said duration of time of said leading injection and said duration of time of said trailing injection in response to changes in said intake valve duration.