Computers and Control Systems: Adjustments

IDLE SPEED

Idle Air Control (IAC) Valve:

1. Start the engine and let it warm up to normal operating temperature (the cooling fan comes on).
2. Connect a tachometer.
3. Disconnect the 2P connector from the IAC Valve.
4. Set the steering in the straight forward position, check the idle speed in the no load condition, with the headlights, cooling fan, and all accessaries are OFF.

Idle Speed Should Be:

Manual 550 ± 50 rpm
Automatic 550 ± 50 rpm (in "N" or "P")

Idle Speed Adjusting Screw Location:

Adjust the idle speed by turning the adjusting screw on the throttle body.


5. Turn the ignition switch OFF, reconnect the 2P connector to the IAC Valve, remove the BACK UP fuse in the underhood relay box for 10 seconds to reset the ECM.
6. Restart the engine, set the steering in the straight forward position and check the idle speed in the no load conditions in which the headlights, blower fan, rear defroster, cooling fan, and air conditioner are not operating.

Idle speed should be:

Manual 700 ± 50 rpm
Automatic 700 ± 50 rpm (in GEAR)

7. Idle the engine for one minute with headlights (Hi) and the rear window defogger ON and check the idle speed.

Idle speed should be:

Manual 770 ± 50 rpm
Automatic 770 ± 50 rpm (in GEAR)

8. Idle the engine for one minute with heater fan switch at HI and air conditioner on, then check the idle speed.

Idle speed should be:
Manual 770 ± 50 rpm
Automatic 770 ± 50 rpm (in GEAR)

NOTE
If the idle speed is not within specification, see COMPUTERS AND CONTROL SYSTEMS