Fig. 3: Identifying Current Controlled Type Injector Pattern
CURRENT WAVEFORM SAMPLES
EXAMPLE #1 - VOLTAGE CONTROLLED DRIVER
The waveform pattern shown in Fig. Fig. 4 indicate a normal current waveform from a Ford 3.0L V6 VIN [U]
engine. This voltage controlled type circuit pulses the injectors in groups of three injectors. Injectors No. 1, 3,
and 5 are pulsed together and cylinders 2, 4, and 6 are pulsed together. The specification for an acceptable bank
resistance is 4.4 ohms. Using Ohm's Law and assuming a hot run voltage of 14 volts, we determine that the
bank would draw a current of 3.2 amps.
However this is not the case because as the injector windings become saturated, counter voltage is created
which impedes the current flow. This, coupled with the inherent resistance of the driver's transistor, impedes the
current flow even more. So, what is a known good value for a dynamic current draw on a voltage controlled
bank of injectors? The waveform pattern shown below indicates a good parallel injector current flow of 2 amps.
1998 Chevrolet Pickup C1500
GENERAL INFORMATION Waveforms - Injector Pattern Tutorial