How to Replace the Spark Plugs on a 1999 Ford Expedition

by Carl PruitUpdated November 07, 2017

Items you will need

  • Spark plugs for 1999 Ford Expedition

  • Spark plug wrench

  • Spark plug gapper

  • Socket wrench set

  • Screwdrivers

  • Pliers

  • WD-40

One of the primary keys to keeping your 1999 Ford Expedition running in top shape is conducting regular maintenance. Following a regular schedule of tuneups and fluid replacements will keep your vehicle operating for a long time. One of the most critical areas of car maintenance is regular spark plugs replacement. A damaged or burnt spark plug can result in poor gas mileage, a rough running engine and several other problems. Stay on top of your car maintenance and you will have a dependable vehicle.

How to replace the spark plugs on your 1999 ford Expedition

Locate the ignition coils under the intake manifolds of the 4.6 litre V-8 engine. On your 1999 Ford Expedition it will be near the top, with 4 on each side, if you are looking at the engine from the front. Mark each coil to remember which one goes where. Once you remove the coils, you will find the spark plugs where the ignition coils were seated.

Using the wrench, remove the spark plugs from the engine block. If the spark plugs give any resistance, spray around the plug with WD-40 to loosen it up. Be careful not to turn too hard or you could crack the plug.

Set the gap on each new spark plug using the plug gapper. You will find the exact gap size for the 1999 Ford Expedition in your owner's manual. On the 4.6 litre V-8 engine, the gap size will be 0.059. Once you have set the gaps, install each spark plug in the engine block using your spark plug wrench. Don't over-tighten the plugs.

Replace the ignition coils over each spark plug and secure. Check to make sure everything is back in place.


If you are having trouble getting the spark plug to stay seated in the wrench, use a long section of rubber garden hose. Put the non-threaded end of the plug in the hose and get the plug seated in the engine block. Once it is seated, remove the hose and finish tightening with a plug wrench.

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