Here's a general guide. Specific steps may vary slightly depending on the exact engine (4.6L or 5.4L V8). Consult a repair manual specific to your vehicle's year and engine for precise diagrams and torque specifications. A Haynes or Chilton manual would be a good investment.
Tools You'll Need:
* Socket set (metric)
* Ratchet and extensions
* Screwdrivers (Phillips and possibly flathead)
* Electrical connector remover tool (or small flathead screwdriver)
* New Throttle Position Sensor (ensure you get the correct one for your engine)
* Shop rags or paper towels
* Safety glasses
Steps:
1. Locate the TPS: The TPS is usually mounted on the throttle body, which is located on the intake manifold. It's a small sensor with a connector. Refer to your repair manual for the exact location.
2. Disconnect the Battery: Disconnect the negative battery cable.
3. Disconnect the TPS Connector: Carefully unplug the electrical connector from the TPS. Use a connector remover tool to avoid damaging the connector.
4. Remove the TPS Mounting Screws: The TPS is typically held in place by one or two screws. Carefully remove these screws. Pay attention to their length and position.
5. Remove the TPS: Gently pull the TPS straight off the throttle body. Don't force it; it should come off relatively easily.
6. Clean the Throttle Body (Optional but Recommended): While you have access, use a throttle body cleaner to clean any grime or buildup on the throttle body. This will improve performance. Follow the cleaner's instructions carefully.
7. Install the New TPS: Carefully align the new TPS with the mounting holes and install it. Ensure it sits flush against the throttle body.
8. Tighten the Mounting Screws: Tighten the mounting screws to the specified torque (consult your repair manual). Don't overtighten.
9. Reconnect the TPS Connector: Carefully plug the electrical connector back onto the new TPS.
10. Reconnect the Battery: Reconnect the negative battery cable.
11. Clear the Engine Codes (Optional but Recommended): After installing the new TPS, it's a good idea to clear any trouble codes that may have been stored in the car's computer. This can be done with a scan tool (OBD-II reader).
12. Test Drive: After completing the replacement, take the vehicle for a test drive to ensure everything is working correctly. Check for smooth throttle response and acceleration.
Important Considerations:
* Engine type: The exact location and procedure might slightly differ between the 4.6L and 5.4L V8 engines. Always refer to a repair manual specific to your engine.
* Torque specifications: Over-tightening the mounting screws can damage the TPS or throttle body. Always use the correct torque specification.
* Cleanliness: Keep the area clean to avoid debris getting into the throttle body.
* Safety: Always disconnect the battery before working on the electrical system.
This guide provides a general overview. Refer to a repair manual for detailed instructions and diagrams specific to your 1998 Ford Expedition Eddie Bauer. If you are uncomfortable performing this repair yourself, take it to a qualified mechanic.
