Tools You'll Likely Need:
* Socket wrench set (metric)
* Screwdrivers (Phillips and flathead)
* Pliers
* Rags or shop towels
* Possibly a small mirror or inspection light
* New throttle body gasket (highly recommended)
Procedure:
1. Disconnect the Battery: This is crucial to prevent accidental shorts.
2. Disconnect the Throttle Cable: Locate the throttle cable attached to the throttle body. There's usually a clamp or bolt securing it. Loosen it and carefully disconnect the cable. Take a picture or make a note of how it's connected for reassembly.
3. Disconnect the Throttle Position Sensor (TPS): This sensor is usually mounted on the throttle body. Unplug the electrical connector. Again, a picture is helpful.
4. Disconnect the Idle Air Control (IAC) Valve (if separate): Some models have a separate IAC valve; others integrate it into the throttle body. If separate, unplug the electrical connector and remove any fasteners securing it to the throttle body.
5. Disconnect the Vacuum Lines: Several vacuum lines might be connected to the throttle body. Carefully disconnect each one, noting their location. Use a small diameter vacuum line puller if the lines are tough.
6. Remove the Throttle Body Bolts: Locate the bolts securing the throttle body to the intake manifold. Usually, there are two or three. Remove them carefully.
7. Remove the Throttle Body: Gently rock the throttle body back and forth to break the seal. Once loose, carefully pull it away from the intake manifold. Be mindful of the gasket, as it will likely stay stuck to either the manifold or the throttle body.
8. Clean the Throttle Body: Now's the perfect time to clean the throttle body using a throttle body cleaner. Follow the cleaner's instructions carefully. Do not use anything abrasive.
9. Install the New Gasket: Before installing the new throttle body, carefully install the new gasket onto the intake manifold.
10. Install the Throttle Body: Carefully align the throttle body with the intake manifold and install the bolts. Tighten them evenly and to the manufacturer's specified torque.
11. Reconnect Everything: Reconnect the throttle cable, TPS connector, IAC valve connector (if applicable), and vacuum lines in the reverse order of removal. Double-check everything.
12. Reconnect the Battery: Reconnect the negative battery terminal.
13. Start the Engine and Check for Issues: Start the engine and listen for any unusual noises or rough running. Check for vacuum leaks. If problems persist, re-check all connections.
Important Considerations:
* Consult a Repair Manual: A repair manual specific to your 1998 Pontiac Transport is highly recommended. It will provide diagrams, torque specifications, and detailed instructions specific to your vehicle. This guide is a generalization and may not be perfectly accurate for your specific model.
* Torque Specifications: Use a torque wrench to tighten the bolts to the manufacturer's specifications to prevent damage.
* Gasket Replacement: Always replace the throttle body gasket. Reusing an old gasket can lead to vacuum leaks.
If you're uncomfortable performing this repair, it's best to take your vehicle to a qualified mechanic. Improper installation can lead to drivability problems.
