The effect of port injected small fuel droplets which were generated by a 2-phase Injector(Air-Assisted Fuel Injector, AAFI) was evaluated for several different conditions of engine operation. The experimental results were compared with those of conventional MPI (Multi-Point Injector). When the deflector was not used, AAFI produced fuel droplets on the order of 20.0 micrometer Sauter Mean Diameter (SMD). With deflector which restricts the initial spray angle to 60˚, SMD of AAFI was 32.8 micrometer and the fuel spray injected from MPI showed 132.6 micrometer SMD. AAFI reduced HC emission especially during cold condition in comparison to MPI at ECU (Electronic Control Unit) controlled fuel injection timing. AAFI also represented consistency of HC emission over various fuel injection timing, including intake-valve open period. AAFI is considered to be very advantageous for transient condition.