Ford Crown Victoria/Grand Marquis 1989-1998

Spark Plug Wires



See Figures 1 and 2

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Fig. Fig. 1: Checking plug wire resistance through the distributor cap with an ohmmeter

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Fig. Fig. 2: Checking individual plug wire resistance with a digital ohmmeter

At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring.

Every 50,000 miles (80,000 km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

To check resistance, an ohmmeter should be used on each wire to test resistance between the end connectors. Remove and install/replace the wires in order, one-by-one.

Resistance on these wires should be 4,000-6,000 ohms per foot. To properly measure this, remove the wires from the plugs and the coil pack. Do not pierce any ignition wire for any reason. Measure only from the two ends. Take the length and multiply it by 6,000 to achieve the maximum resistance allowable in each wire, resistance should not exceed this value. If resistance does exceed this value, replace the wire.

Whenever the high tension wires are removed from the plugs, coil, or distributor, silicone grease must be applied to the boot before reconnection. Coat the entire interior surface with Ford silicone grease D7AZ-19A331-A or its equivalent.


See Figures 3 through 8

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Fig. Fig. 3: Grasp the plug wire and carefully twist the wire to release the retainer from the spark plug

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Fig. Fig. 4: If the plug wire is stubborn, a pair of special removal pliers is recommended to remove the wires from the plugs

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Fig. Fig. 5: Carefully remove the plug wire from the cylinder head

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Fig. Fig. 6: Remove the plug wires from the ignition coil by squeezing the retaining tabs and carefully lifting the wires up

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Fig. Fig. 7: Disconnect the plug wire retaining clips from the wires and ...

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Fig. Fig. 8: ... remove the plug wires from the engine

  1. Remove the air cleaner inlet tube.
  3. Label each spark plug wire and make a note of its routing.

Don't rely on wiring diagrams or sketches for spark plug wire routing. Improper arrangement of spark plug wires will induce voltage between wires, causing misfiring and surging. Be careful to arrange spark plug wires properly.

  1. Starting with the longest wire, disconnect the spark plug wire from the spark plug and then from the coil pack (4.6L) or distributor cap (5.0/5.8L).
  3. Disconnect the ignition wire from the coil pack by squeezing the locking tabs and twisting while pulling upward.

To install:
  1. If replacing the spark plug wires, match the old wire with an appropriately sized wire in the new set.
  3. Lubricate the boots and terminals with dielectric grease and install the wire on the coil pack. Make sure the wire snaps into place.
  5. Route the wire in the exact path as the original and connect the wire to the spark plug.
  7. Repeat the process for each remaining wire, working from the longest wire to the shortest.
  9. Install the air cleaner inlet tube.