The effect of injector parameters on the mixture preparation process was investigated by using simulation on a port fuel injection engine. To this end the effect of fuel injection timing on power and emission characteristics under full-load condition was studied by experiments. Results show that by improving the injector design

homogeneous mixture required by open-valve injection can be produced by adjusting the injector’s spray cone angle

installation angle and installation position. Through the optimization of injection timing

a best end of injection (EOI) of the best open valve injection is discovered at full load conditions and at a speed of 1 200 r/min～5 600 r/min. When the EOI is 420°

the engine power is increased by 1%～2% compared with that of the closed valve injection

and total hydrocarbons(THC) emissions are almost not affected. While the closed-valve injection has better power performance at the speed of 6 000 r/min.