cyl4 missfire 09 accent 1.6

Assuming that you're checking the voltage at the connector for the injector with the connector unplugged, this is the answer. If you have the ground signal going from the ECM to that injector, you must be just missing the power to that injector. The ground signal should be pulsing( that's what the computer controls) The voltage wire to the injector should always be there as long as the engine is cranking or the engine is running. All injectors get the voltage from the same relay. There has to be break in the positive wire to #4 injector. It doesn't matter where the positive wire is broken. Just cut that wire at the #4 injector connector and tap a wire from that cut wire going to #4 injector connector and splice it into the positive wire at the #3 injector. The color of the positive wire is the same for all 4 injectors. Like I said, this is a correction if your missing voltage at that connector. I'm a Hyundai tech. Any problems please repost