- Make sure the following conditions prevail before adjusting the idle speed:
- Air cleaner installed.
- Engine has reached normal operating temperature.
- All pipes and hoses of the air intake system are connected.
- All accessories are switched off.
- Electronic fuel injection (EFI) wiring connections tightly connected.
- Ignition timing correct.
- Transmission in Neutral, parking brake set and wheels blocked.
- Connect a suitable tachometer to the engine, always connect the positive terminal of the tachometer to the engine service connector (IG terminal) located under in the engine compartment. Using a suitable piece of jumper wire short the terminals of the check engine connector (1983-88 T and E 1 1989-90 TE 1 and E 1 ), located in the engine compartment.
- Connect a voltmeter to the Vf and E 1 (Vf 1 1989-90) terminals of the engine (diagnosis) service connector, located in the engine compartment.
- Warm up the oxygen sensor with the engine at running at 2,500 rpm for approximately 2 minutes.
- Maintain the engine speed at 2,500 rpm.
- Check that the needle on the voltmeter fluctuates 8 times or more in 10 seconds. If not, inspect the EFI system and replace the oxygen sensor, if necessary.
With the engine idling, check that the idle RPM is within specifications:
A/C switch ON -900 rpm in Neutral and 750 rpm in Drive.
- With the engine idling, check that the Vf voltage is 2.5 plus or minus 1.25 volts. If not, check the intake system for a vacuum leak. If there is no vacuum leak in the intake manifold, investigate other areas.
- If the idle speed is out of specifications, remove the rubber plug from the side of the throttle body exposing the idle adjustment screw.
- Adjust the idle speed to obtain the specified rpm and reinstall the rubber plug.
Always make sure that the idle speed control valve (ISC) is operating properly before making any idle speed adjustments. To see if the ISC valve is working properly, confirm that there is a clicking sound heard from it immediately after stopping the engine.