Computers and Control Systems: Adjustments

NOTE: A base RPM adjustment is not normally required and should not be performed unless the base idle stop screw had inadvertently been misadjusted during servicing. On replacement throttle bodies, the idle stop screw is not adjusted and is not covered with a plug.

ADJUSTMENT:

1. Back idle stop screw out until there is an air gap between the screw and the throttle lever.
2. Turn the screw in until it just touches the throttle lever.
3. Turn the screw in an additional 1 1/2 turns.
4. Block drive wheels and apply parking brake.
5. Connect a scan tool to the ALDL connector.
6. Turn the ignition on.
7. Select TPS display on the scan tool, and adjust the TPS to specifications (see MECHANICAL SPECIFICATIONS under SPECIFICATIONS).
8. Select "Field Service Mode" on scan tool. Wait at least 45 seconds to allow IAC pintle to seat in the throttle body. Disconnect the IAC connector and exit the "Field Service Mode".
9. Place transmission in Park (A/T) or neutral (M/T) and start the engine. Warm up until operating temperature and closed loop conditions are reached.
10. Verify that minimum idle speed is within specifications.
11. Turn ignition off.
12. Connect IAC connector.
13. Turn the ignition on and recheck the TPS voltage. Adjust if necessary.
14. Turn the ignition off for ten seconds to seat the IAC pintle
15. Start the engine and check for proper idle operation.