Fuel injection control system for engine

摘要

To additionally inject, in an engine transient state, a lack of a fuel supply amount on the basis of a current engine state and hence to improve drivability and fuel consumption. A required fuel amount is calculated at a predetermined calculation cycle, and a fuel injection amount Tin(Upper) to be injected from an upstream injection valve and a fuel injection amount Tin(Lower) to be injected from a downstream injection valve are calculated. After fuel injection on the basis of the calculated fuel injection amounts, a lack TiADDF of the fuel injection amounts immediately before re-calculation of a required fuel amount at the calculation cycle coming until the end of an intake stroke (end of an intake valve opening period) by subtracting the fuel injection amounts from the re-calculated required fuel amount. The calculated lack TiADDF is injected from the downstream injection valve during the intake stroke (in stages 6 and 7). Part of a fuel injected from each of the fuel injection valves, which part has adhered on an inner wall of an intake pipe and is released to be supplied in an engine, is calculated in accordance with a predetermined adhesion ratio and a predetermined release ratio, and the above lack TiADDF is determined in consideration of the calculated part of the fuel.