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FUEL INJ - Fuel Injector Mode is specifically set up for fast and easy
injector circuit diagnosis. One quick connection to the circuit and the
Maestro
™
will display all the needed fuel injector testing information that
would normally require using a lab-scope.
Below is an example of a typical fuel injector voltage waveform on a lab
FUEL INJECTOR MODE
WWW.POWERPROBETEK.COM
scope. This is displaying
a single injector pulse.
The vertical axis rep-
resents circuit voltage
and the horizontal axis
represents time.
Following the waveform
from left to right, you can
see the circuit voltage
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 injector produce a magnetic field when the
injector is energized. Each time an injector is turned off, this magnetic field
collapses back into the injector windings and induces a hi-voltage spike.
The 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
Maestro
™ 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 synchro-
nized with the injector signal from the ECM with a corresponding tone from
the speaker out. These audible and visual cues can quickly identify any
intermittent loss of signal from the ECM.
