Malfunctional detecting apparatus for an assist air control system for internal combustion engines

A malfunctional detecting apparatus for an assist air control system for internal combustion engines comprising:

• a fuel injection valve for injecting fuel from an injection port thereof into an intake passage at downstream side of a throttle valve;
• assist air passage means for defining an assist air passage having an opening toward said injection port of said fuel injection valve through which assist air passes;
• an air control valve disposed in said assist air passage for being operated to open and close said assist air passage;
• control means for controlling quantity of air to be introduced into said opening of said assist air passage by opening and closing said air control valve in synchronism with said fuel injection valve;
• an assist air passage pressure sensor disposed in said assist air passage at downstream side of said air control valve for detecting air pressure in said assist air passage;
• and
• malfunctional judging means for said air control valve based on air pressure detected by said assist air passage pressure sensor immediate after said air control valve is operated.