Fuel Injector
Battery voltage for injector is supplied from main relay and then passes through injector resistor (except Civic 1.5L and standard) before reaching injectors. Injectors are energized when ECU supplies a ground circuit for individual injectors. Because plunger valve lift and fuel pressure are constant, air/fuel ratio is determined solely by length of time that injector is open.
NOTE:
Civic 1.5L and standard models use 2 injectors located in throttle body. All other models have injectors located in intake manifold, one injector for each cylinder.