Five Hundred, Montego 2006-2007

Spark Plugs



Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.

Check spark plug gap before installation. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge (please refer to the Tune-Up Specifications chart for details) must pass between the electrodes with a slight drag.

NEVER adjust the gap on a used platinum type spark plug.

Always check the gap on new plugs as they are not always set correctly at the factory. Do not use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all. Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Absolutely never attempt to bend the center electrode. Also, be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.

Click image to see an enlarged view

Fig. "a1p40"" Inspect the spark plug to determine engine running conditions

Click image to see an enlarged view

Fig. "S212"" A variety of tools and gauges are needed for spark plug service

Click image to see an enlarged view

Fig. "S903"" Checking the spark plug gap with a feeler gauge

Click image to see an enlarged view

Fig. "S904"" Adjusting the spark plug gap

Click image to see an enlarged view

Fig. "S141"" If the standard plug is in good condition, the electrode may be filed flat-WARNING: do not file platinum plugs

Removal & Installation

When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once, because, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.

  1. Disconnect the negative battery cable.
  3. Remove the upper intake manifold.
  5. Disconnect the ignition coil electrical connectors.
  7. Remove the ignition coil bolts.
  9. When removing the ignition coils, a slight twisting motion will break the seal and ease removal.
  11. Remove the ignition coils.
  13. Remove the spark plugs.

To install:

  1. To install, reverse the removal procedure. Tighten the spark plugs to 11 ft. lbs. (15 Nm).