Patent ID: 6973912

Claim:
A method of controlling operation of an internal combustion engine having a main body, an intake manifold connected to said main body and having a plurality of parallel branch pipes and a common pipe held in communication with said branch pipes, said intake manifold having a main intake passage defined therein, a throttle valve connected to said common pipe and openable and closable for regulating intake air drawn through said main intake passage into the internal combustion engine, an auxiliary intake passage disposed separately from said main intake passage and connected to said branch pipes in communication with said main intake passage, and an amount-of-air detector disposed in said auxiliary intake passage for detecting an amount of intake air drawn through said auxiliary intake passage into the internal combustion engine, said method comprising the steps of: dividing an integrated value of the amount of intake air detected by said amount-of-air detector between a preceding intake stroke and a present intake stroke by a time period between said preceding intake stroke and said present intake stroke, thereby calculating an average value of the amount of intake air; calculating the integrated value of the amount of intake air detected by said amount-of-air detector within a preset amount-of-air detecting time period based on an actual amount of intake air that is actually drawn into the internal combustion engine in said preceding intake stroke; determining whether a predetermined time period in the preset amount-of-air detecting time period has elapsed after said amount-of-air detector has started detecting the amount of intake air in the present intake stroke; after confirming that one half or more of the preset amount-of-air detecting time period has elapsed, multiplying the integrated value of the amount of intake air detected in said one half of the preset amount-of-air detecting time period by a correcting coefficient, and then dividing by said preset amount-of-air detecting time period, thereby calculating an amount of intake air detected in said preset amount-of-air detecting time; subtracting the average value of the amount of intake air between the preceding intake stroke and the present intake stroke from the amount of intake air detected in said preset amount-of-air detecting time, and multiplying the difference by a correcting coefficient, thereby calculating an estimated amount of intake air to be drawn into the internal combustion engine; and supplying the estimated amount of intake air to the internal combustion engine to control operation of the internal combustion engine.