To inhibit occurrence of misfire by utilizing the fact that degree of mixing of fuel and fresh air is larger as injection ratio (quantity of port injection)/(quantity of port injection + quantity of in-cylinder injection ) is larger, in a fuel injection ratio control device adapted to the internal combustion engine provided with a port injection valve and an in-cylinder injection valve.
This device principally determines the injection ratio to the base injection ratio based on an engine operation condition. When fuel cut control is completed while fuel cut control is being executed, injection ratio is determined to a value corrected by multiplying the base injection ratio by a correction coefficient KR (1). The correction coefficient KR is determined to a larger value as residual burned gas quantity Megr is larger and degree of increase of accelerator operation quantity Accp is higher, and is determined to a smaller value as cooling water temperature THW is higher. Consequently, when fuel cut control is completed, injection ratio can be controlled to be a value for inhibiting the occurrence of misfire.
SHINAGAWA TOMOHIRO
HOSOKAWA YOHEI
KORENAGA SHINGO
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