Ignition System - Spark Plug/Ignition Coil Inspection

VOLUME
3

GROUP
Engine

NUMBER
022

MODEL
Sedona, Sorento Amanti

SUBJECT:
SIGMA 3.5 ENGINE SPARK PLUG & IGNITION COIL INSPECTION PROCEDURE

This bulletin provides information relating to unnecessary spark plug and ignition coil replacement on Sedona, Sorento and Amanti vehicles with Sigma 3.5 Engines. Proper inspection and testing procedures MUST be used to determine if the spark plugs and/or ignition (IC) coils are bad prior to replacing them. Follow the procedures in this technical service bulletin to inspect and test the spark plugs and ignition coils.

SPARK PLUG CENTER ELECTRODE AND INSULATION RESISTANCE CHECK:

1. Remove spark plug





2. Inspect the spark plug comparing it to the following pictures. The condition of the spark plug electrode end is an indicator of general combustion chamber condition.





3. Using a copper or brass wire brush, carefully remove carbon or any deposits from terminal and electrodes. Carbon or any other deposits MUST be removed before performing resistance check.

4. Spark plug at must be at room temperature (about 68 degrees F.). Using an ohmmeter place one lead on the spark plug terminal and the other lead on the center electrode (illustration A).

5. Check ohm reading with the chart.





Center Electrode Ohm Check





6. Move the ohmmeter lead from the center electrode to the spark plug thread area (illustration B).





7. Check ohm reading with the chart.

Insulation Resistance Check

SPARK PLUG ELECTRODE GAP CHECK:

1. With spark plug removed, insert wire feeler gauge between spark plug electrodes. Adjust air gap or replace, as necessary according to the chart below.





Spark Plug Gap Check

SPARK PLUG GASKET THICKNESS

CHECK:





1. Check spark plug gasket for damage or distortion. If gasket is damaged or distorted replace gasket. Replace spark plug if gasket is non-removable.

2. Check spark plug gasket thickness with calipers per table below.

3. When installing spark plugs;

^ use a very small amount of anti-seize on the spark plug threads,

^ torque the spark plugs to specifications as listed in the chart below.





Spark Plug Gap Table and Torque Specification

IGNITION COIL INSPECTION:

1. Visual Inspection

^ Visually inspect the rubber cap for white discoloration in the area circled. If white discoloration is present it is an indication that there is a pinhole in the rubber allowing the spark voltage to leak through the insulation to ground.





Ignition Coil Inspection Chart





2. Measure Primary Coil Resistance

^ Measure Primary coil resistance using an ohmmeter.

^ Place the leads of the ohmmeter on the terminals as shown in the illustration C.

Check the resistance (if there is current) between terminal 3 and 2 when connecting/disconnecting terminal 1 and terminal (+) after connecting (-) terminal of 3V power to terminal 2 of the power transistor.





Primary Coil Resistance

Replace the power transistor if there is a malfunction.





3. Measure the Secondary Coil Resistance

^ Measure the secondary coil resistance using an ohmmeter.

^ Place the leads of the ohmmeter on the terminals as shown in the illustration D.





Secondary Coil Resistance

4. If ignition coil passes inspection checks 1-3 of the Ignition Coil Inspection, the coil is good and must be reused.