Idle Speed: Adjustments

IDLE SPEED

Self Test Connector:

NOTE: The curb and fast idle speeds are controlled by the EEC processor and the idle speed control device and cannot be adjusted. A change in idle speed normally occurs because of a problem elsewhere. Before proceeding with adjustments verify that the transmission is in PARK or NEUTRAL and parking brake is set.

1. With engine OFF, remove the air cleaner. Connect jumper wire between the Self-Test Input (STI) and Signal Return Pin on the Self Test connector.
2. Turn the ignition key ON but DO NOT start engine. ISC plunger will retract within 10-15 seconds if ISC plunger does not retract, perform EEC-IV diagnostics. Refer to COMPUTERIZED ENGINE CONTROLS.
3. Disconnect vehicle harness from the ISC motor. Turn ignition key OFF and remove jumper wire.
4. START engine and check idle rpm. If it is not 575-625 rpm A/T (625-675 rpm M/T) less than specified continue with Step 5.
5. Turn ignition key OFF. Remove Throttle Body assembly, refer to COMPONENT REPLACEMENT AND REPAIR PROCEDURES.

Throttle Stop Adjusting Screw:

6. Remove the plug that covers the throttle stop adjusting screw.
7. Remove the old throttle stop adjusting screw and install a new screw.
8. Install the Throttle Body assembly. START the engine and let it stabilize.
9. Adjust the throttle stop adjusting screw to obtain specified rpm.
10. Shut engine OFF and reconnect vehicle harness to the ISC motor. Reinstall air cleaner.