GxT V055-01 Diagnostic Analyzer - Manual (Page 10)

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The EngineLink will analyze the ignition and determine
the polarity of each of the KV clips. When complete,
a screen will advise that the throttle should be opened
abruptly. This sets the minimum and maximum readings.
The composite screen will appear, showing the average
readings for all coils.
SPARK BURN DURATION
The spark burn duration on a DIS is usually between 0.5
and 1.5 mSec. Long burn duration comes from narrow
or fouled plug gaps, insulation shorts, low cylinder
compression, and rich fuel mixtures. Short burn duration
is caused by breaks in ignition secondary wires, wide
spark plug gaps, worn plugs, high circuit resistance, and
very lean fuel mixtures.
A reduction in burn durations, with snap acceleration, is
an ideal check for spark plug gaps that have the sharp
edges worn off, and to see that insulation does not arc
through.
Problems like wire breaks and high secondary resistance
are most easily detected at a moderate and steady RPM
between 1000 and 2000.
FIRING KV — Live and Maximum
Firing KV is the voltage that is required to start ionizing
the air/fuel mix in the spark plug gap. For the ignition
to always work, the KV available from the coil must be
more than the highest KV requirement. Causes of high
KV can be a wide or worn plug gap, a broken sparkwire conductor, or a lean fuel mixture. Unusually low
KV can be from a fouled plug gap, secondary insulation failure, or low compression. Typical live KV is 5
to 10 at a steady RPM with not more than a 5 KV difference between the highest and lowest.
EXHAUST KV
Also known as waste KV. On double output coils, the spark plug in the cylinder on its exhaust stroke
serves as the ground path for the coil. Exhaust KV should be low because, without compression in the
cylinder, little voltage should be needed to fire the plug. Exhaust spark is normally less than 5 KV. Higher
readings indicate the possibility of a broken spark plug wire, a wide plug gap, or a fouled plug on the
opposite side.
INDIVIDUAL CYLINDER READINGS
Use the up and down arrows to see four additional screens that show data for the individual cylinders.
The burn time bar graph screen shows live spark burn time for each cylinder. The number in the upper
left corner shows the average for all cylinders. Press HELP to see an explanation of the screen. The burn
time numerical screen shows min., max., and live spark burn time for each cylinder in numerical format.
The KV bar graph screen shows live KiloVolt readings for each cylinder. The bottom of the left bar
represents the minimum kilovolts and the top is the maximum. The top of the middle bar shows the live
reading for firing KV and the right bar shows exhaust KV.
Ignition Secondary - DIS