Chart C-4F-1 Misfire at Idle (C3I Ignition System)

Chart C-4F-1 - C3-I Misfire at Idle:

Wiring Diagram for Chart C-4F-1 - C3-I Misfire at Idle:

CHART C-4F-1 - C3-I MISFIRE AT IDLE

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 under the load only, the diagnostic chart C-4F-2 must be used. Engine rpm should drop approximately equally on all plug leads.

2. 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.)

3. By grounding the opposite plug lead of the affected coil, a faulty spark plug (extremely high resistance) may be detected.

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

5. 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.