Hummer H2. Manual — part 162

manufacturer.

Fig. 12: Single Injector w/Normal Current Flow - Current Pattern

EXAMPLE #5 - CURRENT CONTROLLED DRIVER

The known-good waveform in Fig. Fig. 13 is from a Chrysler 3.0L V6 PFI VIN [3]. It is a perfect example of
the peak and hold theory. The waveform shows a 1-amp per division current flow, ramping to 4 amps and then
decreasing to 1-amp to hold the injector open.

Fig. 13: Injector Bank w/Normal Current Flow - Current Pattern

EXAMPLE #6 - CURRENT CONTROLLED DRIVER

This next known-good waveform is from a Ford 5.0L V8 CFI VIN [F]. See Fig. 14 . The pattern, which is set
on a 250 milliamps scale, indicates a 1.25 amp peak draw and a hold at 350 milliamps.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Waveforms - Injector Pattern Tutorial

Fig. 14: Single Injector w/Normal Current Flow - Current Pattern

EXAMPLE #7 - CURRENT CONTROLLED DRIVER

The known-good current controlled type waveform in Fig. Fig. 15 is from a GM 2.0L TBI VIN [1]. With the
lab scope set at 2 amps per division, notice that this system peaks at 4 amps and holds at 1 amp.

The next waveform is from the same type of engine, except that it shows a faulty injector. See Fig. 16 . Notice
that the current went to almost 5 amps and stayed at 1 amp during the hold pattern. Excessive amounts of
current flow from bad injectors are a common source of intermittent computer shutdown. Using a current
waveform pattern is the most accurate method of pinpointing this problem.

Fig. 15: Single Injector w/Normal Current Flow - Current Pattern

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Waveforms - Injector Pattern Tutorial

Fig. 16: Single Injector w/Excessive Current Flow - Current Pattern

EXAMPLE #8 - CURRENT CONTROLLED DRIVER

This known-good CPI system waveform from a GM 4.3L V6 CPI VIN [W] peaks at 4 amps and holds at 1-
amp. See Fig. 17 for waveform.

Fig. 17: Single Injector w/Normal Current Flow - Current Pattern

VOLTAGE WAVEFORM SAMPLES

EXAMPLE #1 - VOLTAGE CONTROLLED DRIVER

These two known-good waveform patterns are from a Ford 4.6L V8 VIN [W]. Fig. Fig. 18 illustrates the 64
volt inductive kick on this engine, indicating no clamping is occurring. The second pattern, Fig. Fig. 19 , was
taken during hot idle, closed loop, and no load.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Waveforms - Injector Pattern Tutorial

Fig. 18: Injector Bank - Known Good - Voltage Pattern

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Waveforms - Injector Pattern Tutorial