In this paper, the injectors with normal quantity, over quantity of +10%, under quantities of -10% and –30%, were mounted on S-ENG and P-ENG in order to measure the voltage energy, current energy and power supplied to the injectors and the fuel economy under several speed of rpm conditions. The voltage and current energy of S-ENG was greater than P-ENG, and the power of S-ENG was measured and analyzed 4.8 times higher than that of P-ENG at all injectors, and the tendency of carbon dioxide emissions calculated from fuel efficiency measurement results was not significantly affected by the type of injectors, but P-ENG was measured to be slightly affected by the type of injectors. It is assumed that the model year and mileage of the test vehicle affects this tendency.