GxT Ferret 54 ENGINE DIAGNOSTIC CENTER - Manual (Page 36)

IGNITION SECONDARY — DIS
Press IGNITION, SELECT Secondary and press NEXT. The Diagnostic center 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.
This screen will appear, showing the average readings for all coils:
~ IGNITION SECONDARY
839 RPM 190û Battery 14.25 Volt
Burn (Avg) 1.3mS Exh (Avg) 2 KV
Live (Avg) 10KV Max (Avg) 21 KV
Measurements include:
4-7
BURN
TIME
FIRING
KV
COIL SECONDARY WAVEFORM
T
HE
KV S
PARK
C
LIPS ARE DESIGNED TO BE
SENSITIVE
. K
EEP THEM SEPARATED TO AVOID
PICKING UP SIGNALS FROM AN ADJACENT WIRE
.
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 caused by a change of
burning fuel within the plug gap. This 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.
When comparing live burn duration of each
cylinder, a difference of more than 0.3 mSec
is significant.
SPARK BURN DURATION
The spark burn duration is affected by the
energy available to push the spark current
through the spark plug circuit. If there is little
resistance to block the current, the spark will
go longer; more resistance, and it will be
shorter. 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.