Secondary Ignition System Display Diagnosis
Procedure1. Connect an engine analyzer to view parade display of secondary ignition system.
2. Start the engine and slowly increase engine speed from idle to 1,300 rpm.
3. Compare the engine analyzer display to the following display illustrations in the Evaluation of Secondary Display.
NOTE
^ The illustrations shown are for the 2.3L four cylinder model, but are typical for the 3.0L and 4.0L engines.
Evaluation of Secondary Display
NOTE
^ The 2.3L and 4.0L B-Truck have the capability of operating in a multi-strike mode (the spark plugs are fired four (4) strikes per firing). The operating modes are limited to about 1500 rpm. Although the PCM provides these operating modes, the PCM must also request them in order for the operating modes to be activated. Result #1 through Result #5 display multi-strike operating modes.
Result 1
The average value of spark plug firing voltage is 20 kV or less with evenness of spark plug firing voltage 8 kV or less.
If the result is as indicated, the ignition system is OK.
Result 2
The average value of spark plug firing voltage is greater than 20 kV with evenness of spark plug firing voltage 8 kV or less.
If the result is as indicated, check the following:
^ High tension leads for proper installation in coil
^ Resistance of high-tension lead
^ Spark plug gap
Result 3
Evenness of spark plug firing voltage is greater than 8 kV.
If the result is as indicated, check the following:
^ Spark plug gap
Result 4
Consistently high spark plug firing voltage in one or more cylinders.
If the result is as indicated, check the following:
^ High-tension lead connections (not firmly connected)
^ Spark plug gap
^ Resistance of high-tension leads
Result 5
Consistently low spark plug firing voltage or stopping spark line in one or more cylinders.
If the result is as indicated, check the following:
^ Fouled spark plugs
^ Spark plug gap
^ Grounded high-tension leads