Example #3 - Voltage Controlled Driver
Example #3 is of a Ford 5.0L V8 SEFI. Fig. Fig 1 shows a waveform of an individual injector at idle with the Lab Scope set on 200 milliamps per division. Notice the dimple in the rising edge. This dimple indicates the actual opening of the injector (set point) occurred at 400 milliamps and current peaked at 750 milliamps. This is a good specification for this engine.
The next waveform pattern in Fig. Fig 2 shows an abnormality with another injector. With the Lab Scope set on 500 milliamps per division, you can see that the current waveform indicates a 1200 milliamp draw. This is a faulty injector.
Abnormally low resistance injectors create excessive current draw, causing rough idle, and possible computer driver damage.
