GxT Ferret 54 ENGINE DIAGNOSTIC CENTER - Manual (Page 34)

IGNITION PRIMARY — Distributor
Press IGNITION, SELECT Primary and press NEXT. If a Distributor Ignition was selected during
Engine Setup , this screen will appear.
839 RPM 190û Battery 14.25V
Ign Energy 38 Driver 0.9V
Dwell 2.9mS~ Oscillations 2
Dwell Var 2.0ß Timing Var 2.3ß
4-5
IGNITION ENERGY
Ignition energy is proportional to the primary
energizing current and the quality of the
ignition coil inductance. The signal comes
from the ignition coil primary minus [TACH]
terminal through the Coil Primary Clip
connection. The engine must be cranking or
running to produce a readable signal.
As the figure shows, Ignition energy strength
is the voltage times the spark duration
milliSeconds, as measured at the coil
primary. This indicates the coil “kick” in
milliVoltSeconds (mVSec).
COIL OSCILLATIONS
This is an indicator of liveliness in the ignition
coil. Shorts in coil insulation or in connected
components usually dampen the oscillations
so they are reduced or eliminated.
Points driven ignition coils usually show 4 to
8 oscillations, which are more than electronic
ignitions that do 1 to 4. Some Chrysler
ignition modules begin dwell immediately
after the spark burn, so they normally do not
show any oscillations.
Typical standard ignition coils produce 25 to
40 mVSec. High energy ignitions have 40 to
60 mVSec. Readings below 20 mVS suggest
that inadequate ignition energy is being
delivered by the coil.
Low coil current may be the reason, caused
by a bad primary connection, bad drive
module, worn points, low dwell time, low
battery voltage, or an open ballast resistor
bypass switch.
Low ignition energy and good driver voltage
may suggest high resistance between battery
positive and coil negative. If dwell time is also
low, then check the ignition module.
GROUND
SPARK
BURN
TIME
COIL
IGNITION ENERGY
AREA
BATTERY
VOLTAGE
COIL PRIMARY (TACH) SIGNAL