One of the primary keys to keep your 1999 Ford Expedition running in top shape is to conduct 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 plug replacement. A damaged or burnt spark plug can result in poor gas mileage, a rough running engine and several other problems.
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 four on each side, if looking at the engine from the front. Mark each coil to remember where each goes. 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. Don't 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.
