Hyundai Sonata LF: Engine Control System / Injector Troubleshooting
The three waveforms below are taken from the #1 and #4
injectors. The top waveform is from the high side (feed side) of the #1
and #4 injectors, while the middle waveform is from the low side (ground
side) of the #1 injector and the bottom waveform is from the low side
of the #4 injector.
The middle waveform is the same as the top waveform because
there is no ground for the circuit. With no current flowing in the
circuit, the #1 injector is not energized and fuel does not flow.
The bottom waveform shows that ground is supplied and there
is a voltage drop across the #4 injector. With current flowing in the
circuit, the #4 injector is energized and fuel flows.

Other information:
Replacement
1.
Disconnect the negative (-) battery terminal.
2.
After loosening the bolts remove the main crash pad and cowl cross bar assembly together.
(Refer to Heater -"Heater Unit")
3.
Remove the heater and blower assembly.
(Refer to Heater -"Heater Unit")
4...
Removal
•
When gear actuator removing, set control shaft lever to neutral position.
1.
Remove the air cleaner assembly and air duct.
(Refer to Engine Mechnical System - "Air cleaner")
2.
Remove the battery and tray...