General Steps (but consult a repair manual!):
1. Safety First: Disconnect the negative terminal from your battery. This prevents accidental shorts and damage to your vehicle's electrical system.
2. Gather Tools: You'll need:
* A socket wrench with the correct size for your spark plugs (likely a 5/8" or 13/16" deep well socket, but CHECK your vehicle's specifications).
* A spark plug socket extension.
* A ratchet.
* Possibly a swivel adapter for better access in tight spaces.
* A new set of spark plugs (the correct type for your engine is CRITICAL; check your owner's manual or a parts store).
* Gloves
* Possibly a torque wrench (highly recommended to avoid damaging threads)
3. Access the Spark Plugs: This is where it gets engine-specific. You'll likely need to remove some components to get adequate access. Consult your repair manual, but expect to possibly remove:
* Air intake system: This often needs to be moved or removed entirely.
* Some wiring harnesses: Gently move these out of the way, taking care not to damage connectors.
* Possibly the coil packs: These are usually held on by bolts or clips. They cover the spark plugs and need to be removed to access the plugs. Label the coil packs' positions before removal if they're not uniquely identified.
4. Remove the Spark Plugs: Carefully loosen the spark plugs with your socket and ratchet. Avoid cross-threading. Once loosened, use your fingers to carefully unscrew the remaining way.
5. Clean the Well: Use compressed air to blow out any debris from the spark plug wells to prevent dirt from getting into the new plugs.
6. Install New Spark Plugs: Carefully hand-thread the new spark plugs into the wells. Do NOT force them; if they don't go in easily, check for cross-threading. Tighten the plugs with your socket and ratchet according to the manufacturer's torque specifications (found in your repair manual or on the spark plug packaging). Using a torque wrench is highly recommended.
7. Reassemble Everything: Reinstall the coil packs (if you removed them), wiring harnesses, air intake system, and any other components you disconnected.
8. Reconnect the Battery: Attach the negative battery cable.
9. Test the Engine: Start your engine and listen for any unusual noises or misfires.
Crucial Note: This is a general overview. The process can vary significantly depending on your engine. Consult a repair manual specific to your 2006 Ford Expedition's engine (4.6L or 5.4L V8) for detailed, accurate instructions and torque specifications. Attempting this without proper guidance can lead to engine damage. If you're uncomfortable performing this yourself, it's best to have a qualified mechanic do it.
