Patent ID: 7082929

Claim:
A method for determining the amount of fuel injection in an engine system having a crank sensor and airflow sensor, comprising the steps of: computing a speed change of engine revolutions per minute by detecting said engine revolutions per minute from a crank sensor; computing a speed change of an intake-air amount by detecting said intake-air amount from an airflow sensor; comparing the speed change of said engine revolutions per minute and the speed change of said intake-air amount with reference values, respectively, and then deciding whether a diagnosis of generation of vibration and reverse-flow in an intake manifold is required; if diagnosis for generation of the vibration and reverse-flow in said intake manifold is decided to be performed, executing a pre-established logic for determining the vibration and reverse-flow and then deciding whether the vibration and reverse-flow are generated in said intake manifold; if the vibration and reverse-flow are determined to occur in said intake manifold, correcting said intake-air amount, which is restored before the generation of the vibration and reverse-flow, in response to a present engine speed and computing a present intake-air amount; and deciding a fuel injection amount by using the above computed intake-air amount instead of using said intake-air amount measured by said airflow sensor.