Chart C-4F-2 Misfire Under Load (C3I Ignition System)

Chart C-4F-2 - C3-I Misfire Under load:

Wiring Diagram for Chart C-4F-2 - C3-I Misfire Under load:

CHART C-4F-2 - C3-I MISFIRE UNDER LOAD


Circuit Description:

The C3-I uses a waste spark method of spark distribution. In this type of ignition system the ignition module triggers the # 1/4 coil pair resulting in both # 1 and # 4 spark plugs firing at the same time. # 1 cylinder is on the compression stroke at the same time # 4 is on the exhaust stroke, resulting in a lower energy requirement to fire # 4 spark plug. This leaves the remainding high voltage to fire # 1 spark plug.



Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.

1. If the "misfire" complaint exists at idle only, the diagnostic chart C-4F-1 must be used. A spark tester such as a ST-125 must be used because it is essential to verify adequate available secondary voltage at the spark plug. (25,000 volts). Spark should jump the tester gap on all 6 leads. This simulates a "load" condition.

2. If ignition coils are carbon tracked, the coil tower spark plug wire nipples may be damaged.

3. By switching a normally operating coil into the position of the malfunctioning one, a determination can be made as to fault being the coil or C3-I module.