Your Ford 5.4's spark plugs should be changed roughly every 30,000 miles. This will ensure optimum fuel efficiency and power output. When the spark plugs start wearing out, you'll notice a decrease in fuel economy, your engine may misfire, and there will be a general and overall decrease in engine performance. Replacement spark plugs can be purchased from any auto-parts store.
Open the hood and unbolt the three 10 mm bolts holding the throttle-body cover in place using a socket wrench. Then, pull the cover off.
Loosen the screw on the hose clamp that secures the air-intake tubing to the throttle body and pull the tubing off the throttle body.
Unbolt the 8 mm bolts on the brace that holds the thermostat to the power steering using a socket wrench. Then, remove the brace. You'll now be able to see the coil-over packs that supply the power to the Ford truck's spark plugs.
Press in on the tab on the coil-over packs and pull up on the connector to unplug the coil-over packs.
Unbolt the retaining bolt on one of the coil-over packs and pull the coil pack out of the spark-plug well.
Unbolt the spark plug using a socket wrench, socket extension and spark-plug socket. Then, pull the spark plug out of the spark-plug well.
Insert the new spark plug. Start the first few threads by hand tightening them, using the socket extension and socket without the assistance of the wrench. Once the threads have been started, tighten the plugs fully with a socket wrench. This will avoid cross-threading the spark plugs. The rest of the installation is the reverse of removal.
