Changing the spark plugs in a Ford Crown Victoria is not unlike most other similar-size cars in the class. The spark plugs are a crucial part of the ignition system, as they deliver the spark to the engine that allows for combustion. If the spark plugs in your Crown Vic are not working correctly because of old age or damage, the engine may sputter, run poorly or offer weak fuel mileage. Replace the spark plugs according to the maintenance schedule in the owner's manual of your Crown Victoria.
Open the hood of your Crown Victoria, and locate the spark plugs on the engine. Follow the spark plug wires down from the distributor or coil packs to find them if necessary.
Remove the positive battery cable from the terminal, and set it aside.
Remove one spark plug wire at a time from its respective spark plug. Work around the engine one cylinder at a time so you don't mix up the wires and throw off the firing order. If that were to happen, the car would not run properly.
Remove the spark plug from the cylinder you removed the wire from, using a spark plug socket and ratchet. You may need to use an extension between the ratchet and the socket in order to reach the plug.
Set the gap on the new spark plug, using a feeler gauge, by sliding the correct-size shims into the gap between the electrode and the ground on the plug and closing the distance until it is a slightly snug. If your plugs came pre-gapped, you may skip this step.
Coat the threads on the spark plug with a thin coat of anti-seize compound to keep the plug from sticking in the cylinder.
Install the new spark plug into the cylinder, and tighten it with a spark plug socket. Make sure to keep the socket square on the plug; side torque will break the porcelain insulator on the plug, rendering it useless.
Place a small amount of boot grease or dielectric grease in the boot, and reinstall the spark plug wire onto the spark plug. Continue this process, working with one spark plug and one cylinder at a time until you have made it all the way around the motor.
Reinstall the positive battery cable, and close the hood.
