Essential Items:
* Spark Plugs: Replacement is crucial. They wear out and misfiring can cause a host of problems. Use the correct type and gap specified in your owner's manual.
* Spark Plug Wires (Ignition Wires): These can crack, fray, or become brittle with age, leading to misfires. Inspect them carefully and replace if necessary.
* Air Filter: A clogged air filter restricts airflow to the engine, reducing performance and fuel economy. Replace with a new filter.
* Fuel Filter: Similar to the air filter, a clogged fuel filter restricts fuel flow. This is especially important on an older vehicle. Replacement is recommended.
* PCV Valve (Positive Crankcase Ventilation): This valve vents crankcase pressure. A faulty PCV valve can lead to increased engine wear and oil consumption. Inspection and replacement are advised.
* Clean or Replace the Throttle Body: Accumulated grime can restrict airflow. Cleaning is often sufficient, but replacement might be needed if severely damaged.
Highly Recommended Items:
* Inspect and/or Replace Belts (Serpentine Belt): Check for cracks, fraying, or wear. A broken belt can leave you stranded.
* Inspect and/or Replace Hoses: Look for cracks, bulges, or leaks in all coolant and vacuum hoses.
* Fluid Changes: While not strictly part of a "tune-up" in the traditional sense, changing the engine oil and filter, coolant (if needed), and transmission fluid (if needed) at the same time makes good sense for preventative maintenance. Check your owner's manual for recommended intervals.
* Battery Check: Test the battery's health and charge. Consider replacing if necessary.
* Tire Rotation and Pressure Check: Maintain proper tire inflation for optimal fuel economy and tire life. Rotation ensures even wear.
Optional but Potentially Needed Items:
* Ignition Coil(s): These can fail and cause misfires. If you're experiencing misfires after replacing plugs and wires, the ignition coil(s) should be checked.
* Oxygen Sensors: These sensors monitor the exhaust gases and affect fuel efficiency and emissions. They can fail over time and may need replacement. A diagnostic code scan may be necessary to determine their status.
* Mass Airflow Sensor (MAF) Cleaning: A dirty MAF sensor can cause poor performance. Cleaning it is often easier and more cost-effective than replacement.
* Fuel Injector Cleaning: This might be needed depending on fuel quality and vehicle history.
Important Note: A 2004 Ford Expedition is an older vehicle. A full diagnostic scan with a code reader is recommended to identify any underlying issues before performing a tune-up. This scan can prevent unnecessary work and highlight potential problems that could be causing poor performance.
Always consult your owner's manual for specific recommendations and maintenance schedules for your vehicle. If you're not comfortable performing these tasks yourself, take your Expedition to a qualified mechanic.
