Throttle Body Assembly Removal and Replacement

Typical Throttle Body Assembly:

Throttle Body Removal:

Throttle Body Identification:

CAUTION:
^ The throttle bore and valve deposits may be cleaned on the vehicle, using carburetor cleaner and a parts cleaning brush. Do Not use a cleaner that contains Methyl Ethyl Ketone. It is an extremely strong solvent, and not necessary for this type of deposit.
^ The throttle body metal parts may be cleaned following disassembly, in a cold immersion-type cleaner such as GM X-55 or equivalent.
^ The throttle position sensor (TPS) and idle air control (IAC) valve should NOT come in contact with solvent or cleaner, as they may be damaged.

NOTE: An eight digit part identification number is stamped on the bottom of the throttle body casting next to the coolant cover. Refer to this number if servicing, or part replacement is required.

REMOVAL:

1. Disconnect the negative battery cable.
2. Partially drain the radiator, to allow the coolant hoses at the throttle body to be disconnected.
3. Remove the air inlet duct at the throttle body, and crankcase vent pipe at the valve cover grommet.
4. Disconnect the TPS and IAC valve electrical connectors.
5. Disconnect the vacuum harness connector from the throttle body.
6. Disconnect the throttle, T.V. (transmission control), and cruise control cables.
7. Disconnect the coolant hoses from the throttle body.
8. Remove the throttle body attaching bolts.
9. Remove the throttle body assembly and flange gasket, discard the gasket.

CAUTION: Use care in cleaning old gasket material from machined aluminum surfaces. Sharp tools may damage sealing surfaces.

INSTALLATION:

1. Install the throttle body assembly with a new flange gasket.
2. Install the throttle body attaching bolts, and tighten to 27 Nm (20 lb.ft).
3. Connect the coolant hoses to the throttle body.
4. Attach the throttle, T.V., and cruise control cables.

NOTE: Make sure the throttle and cruise control linkage does not hold the throttle open.

5. Connect the vacuum harness connector.
6. Connect the TPS and IAC valve electrical connectors.
7. Install the air inlet duct to the throttle body, and crankcase vent pipe to the valve cover grommet.
8. Refill the radiator.
9. Connect the negative battery cable.
10. With the engine OFF, check to see that the accelerator pedal is free. Depress the pedal to the floor and release.

IDLE STOP SCREW ADJUSTMENT

^ This adjustment should be performed only when installing a replacement throttle body.
^ The idle stop screw is used to regulate the minimum throttle valve position. On original equipment throttle bodies, it is adjusted at the factory, then covered with a plug to discourage unnecessary readjustment.

CAUTION: The minimum throttle valve position is critical to vehicle performance and component durability. If the throttle valve is adjusted too far open, it will cause the IAC valve pintle to constantly bottom on its seat and result in early valve failure. If the throttle valve is not open far enough, the vehicle may not start in cold weather or may stall during warm-up.

PROCEDURE:

NOTE: "Scan" tool is required.

1. Back the throttle stop screw out until an air gap between the screw and the throttle lever can be seen by looking downward from above the throttle body.
2. Turn the stop screw in until it just contacts the throttle lever.
3. Turn the stop screw in 1 1/2 turns further.
4. Place the transaxle in PARK or NEUTRAL.
5. Connect the Tech 1 "Scan" tool to the ALDL connector.
6. Select "IAC System," then select "Idle Learn" in the "MISC. Test" mode.
7. Proceed with the idle learn as directed.
8. START the engine, allow it to reach normal operating temperature and closed loop operation.
9. Using the "Scan" tool, observe the IAC counts.

NOTE:
^ The battery must have been disconnected during the replacement procedure and then reconnected before checking IAC valve counts. This enables the ECM to relearn the IAC valve pintle position.
^ IAC valve counts should be checked with all accessories (A/C, rear defog, etc.), transmission in PARK (A/T) or NEUTRAL (M/T), and engine cooling fan OFF.
^ Make sure the throttle and cruise control cables do not hold the throttle open.
^ With the engine stabilized, IAC valve position should be 10 to 20 counts. If not, repeat the adjustment procedure.