Fuel Injector Mode - Power Probe IV User Manual

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Advanced Testing Operations

Fuel Injector Mode

FUEL INJ = Fuel Injector Mode is specifically set-up for fast and easy injector circuit diagnosis.
One quick connection to the circuit and the Power Probe IV will display all the needed fuel injector
testing information that would normally require using an lab-scope.
Below is an example of a typical fuel injector voltage waveform on a lab scope. This is displaying
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an injector is turned off, this magnetic field collapses back into the injector windings and induces a
hi-voltage spike. This voltage spike is the Inductive Kick Voltage.
The time between when the injector is turned on to when the injector is turned off is simply called the
Injector On-Time and is usually expressed in milliseconds. The Power Probe IV displays each of
these four data points on one screen giving a complete picture of the electrical performance of the
injector and the entire injector circuit.
The Red/Green LEDs above the LCD display will blink and are sychronized with the injector signal
from the ECM with a corresponding tone from the speaker output. These audible and visual cues can
quickly identify any intermittent loss of signal from the ECM.
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a single injector pulse. The vertical
axis represents the circuit voltage
and the horizontal axis represents
time.
Following the waveform from left
to right, you can see the circuit
voltage starts near battery voltage
until the injector is turned on, this is
the Injector Supply Voltage.
Then the voltage will drop to near
zero when the ECM/PCM switch-
es to ground, or ECM Ground
Voltage.
The windings inside of a fuel injec-
tor produce a magnetic field when
the injector is energized. Each time