Idle Speed: Adjustments

NOTE: Because the idle speed is controlled automatically by the Electronic Control Assembly (ECA) through the idle speed control (ISC) valve, usually it is not necessary to check and adjust the idle speed. However, the idle speed should be adjusted when rough idling occurs while the Self Test Input (STI) connector is grounded.
Before adjusting the idle speed, make sure the ignition timing is adjusted to specifications and check the general condition of the engine.

1. Turn OFF all lights and other unnecessary electrical loads. This adjustment must be done while the radiator fan is not running.
2. START the engine and run it at 2,500 to 3,000 rpm in PARK (A/T) or NEUTRAL (M/T).
3. Attach a tachometer to the engine and check that the idle speed is 750 +/- 25 rpm.

Test Connector:

4. Ground the black, single pin STI (test) connector with a jumper wire.

Idle Air Adjustment Screw:

5. If the idle is now not 750 +/- 25 rpm, remove the blind cap from the throttle body and adjust it by turning the idle air adjust screw counter clockwise to increase the idle speed and clockwise to decrease the throttle speed.
CAUTION: DO NOT tamper with the adjustment screw located just to the left of the idle air adjusting screw. Doing so may result in damage to, or the need for the replacement of, the throttle body.
6. After adjusting the idle speed, install the blind cap, disconnect the jumper wire from the STI connector, and remove the tachometer from the engine.