Spark Plug: Description and Operation

The 3.5L engines use platinum resistor spark plugs. They have resistance values of 6,000 to 20,000 ohms when checked with at least a 1000 volt tester. For spark plug identification and specifications, Refer to the Specifications.

Do not use an ohm meter to check the resistance of the spark plugs. This will give an inaccurate reading.

Remove the spark plugs and examine them for burned electrodes and fouled, cracked or broken porcelain insulators. Keep plugs arranged in the order in which they were removed from the engine. An isolated plug displaying an abnormal condition indicates that a problem exists in the corresponding cylinder. Replace spark plugs at the intervals as recommended.

Platinum Pads:

The spark plugs are platinum and have a recommended service life of 100,000 miles for normal driving conditions per schedule A. The spark plugs have a recommended service life of 75,000 miles for serve driving conditions per schedule B. A thin platinum pad is welded to electrode ends. Extreme care must be used to prevent spark plug cross threading, misgapping and ceramic insulator damage during plug removal and installation.

CAUTION: Never attempt to file the electrodes or use a wire brush for cleaning platinum plugs. This would damage the platinum pad which would shorten spark plug life.

Setting Spark Plug Electrode Gap:

Adjust the gap between the electrodes to the dimensions specified in the chart at the end.

Apply a very small amount of anti-seize compound to the threads when reinstalling the vehicle's original spark plugs that have been determined good. Do not apply anti-seize compound to new spark plugs.

NOTE: Anti-seize compound is electrically conductive and can cause engine misfires if not applied correctly. It is extremely important that the anti-seize compound doesn't make contact with the spark plug electrodes or ceramic insulator.

Never force a gap gauge between the platinum electrodes or adjust the gap on platinum spark plugs without reading the Spark Plug Gap Measurement procedures

Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap. Over tightening can also damage the cylinder head.

SPARK PLUG GAP MEASUREMENT

CAUTION:: The Platinum pads can be damaged during the measurement of checking the gap if extreme care is not used.

- USE ONLY A TAPER GAP GAUGE.
- Never force the gap gauge through the platinum pads. Only apply enough force until resistance is felt.
- Never use a wire brush or spark plug cleaner machine to clean platinum spark plugs
- Use an OSHA approved air nozzle when drying gas fouled spark plugs.

If gap adjustment is required of platinum plug, bend only the ground electrode. DO NOT TOUCH the platinum pads. Use only a proper gapping tool and check with a taper gap gauge.

CAUTION: Cleaning of the platinum plug may damage the platinum tip.