Firing, Misfiring

FAULT DIAGNOSIS, FIRING - MISFIRING

Fault Symptom.
Misfiring in any cylinder.

Diagnostic Procedure.
1. Connect the Scan Tool.
Start the engine and run it at idling speed. Ascertain the cylinder on which the engine is misfiring by disconnecting one injector at a time.
Select "INITIATE".
Select "TURN OFF INJECTOR" for each cylinder.
Listen to the engine and observe it to identify the offending cylinder.

2. Check the interface in the 4-pin connector for the ignition coils.
With the ignition switch in the OFF position, unplug the 4-pin connector.
Ignition switch in the ON position.
Connect the test lamp to the female connector as follows
- pin 4 to pin 3 (cyl 1-4)
- pin 4 to pin 1 (cyl 2-5)
- pin 4 to pin 2 (cyl 3-6)
Select "ACTIVATE".
Select "IGNITION CYL 1-4",
"IGNITION CYL 2-5" And
"IGNITION CYL 3-6".
The command activates the relevant ignition coil at a frequency of 0.5 Hz for 30 seconds.
- The test lamp should flash.
At the end of the test turn the ignition switch back to the OFF position.

If the test lamp flashes, proceed to step 4.
If it does not, continue with step 3.

WARNING - HIGH TENSION: The electronic ignition system operates at voltages higher than 40,000 V. Such voltages may be fatal to persons with a weak heart and those who have a pacemaker. So treat the ignition system with great respect.





3. Check the lead between the relevant ignition coil and the control module:
- pin 3 of the connector to pin 1 of the control module
- pin 1 of the connector to pin 20 of the control module
- pin 2 of the connector to pin 21 of the control module for continuity/shorting.

If the lead is OK, continue at "Procedure Before ECM Replacement". Component Tests





4. The fault has been traced to the ignition coil, the high-tension lead (ignition cable) or the spark - plug.
The front cylinder bank (cylinders 2, 4 and 6) is accessible but access to the rear bank (cylinders 1, 3 and 5) necessitates the removal of various components.
Ignition switch in the OFF position.
Disconnect the appropriate high-tension lead from the spark plug and connect it to a test spark plug.
Ground the test spark plug.
Ignition switch in the ON position.
Select "ACTIVATE".
Select "IGNITION CYL" for the cylinder in question.
- The spark plug should produce a spark.

If it does, inspect it and possibly fit a new one.
If it does not, try fitting a new high-tension lead (ignition cable).

Select "IGNITION CYL" for the cylinder in question.
- The test spark plug should produce a spark.

If it does not, fit a new ignition coil.
If it does, fit a new high-tension lead (ignition cable).