Idle Speed and Mixture
EXCEPT 22R-E ENGINES
See Figures 1, 2, 3, 4, 5, 6 and 7
In order to complete this procedure you will need a voltmeter and an EFI idle adjusting wiring harness (Special Service Tool 09842-14010) which is available at your Toyota dealer. If you do not have these tools which are essential to this procedure, the car should be taken to a competent mechanic or dealership equipped for this procedure.
- Behind the battery on the left front fender apron (right front on 1982-85 Supra) is a service connector. Remove the rubber caps from the connector and connect the EFI idle adjusting wiring harness.
- Connect the positive lead of the voltmeter to the red wire of the wiring harness and then connect the negative lead to the black wire.
- Connect a tachometer as per the manufacturer's instructions.
- Warm up the oxygen sensor by running the engine at 2500 rpm for about two minutes.
The needle of the voltmeter should be fluctuating at this time, if not, turn the idle mixture adjusting screw until it does.
- Set the idle speed to specifications (see Tune-Up Specifications chart) by turning the idle speed adjusting screw.
The idle speed should be set immediately after warm-up while the needle of the voltmeter is fluctuating.
- The idle adjustment procedure for the 5M-GE engine is now complete. Follow the remaining steps for the 4M-E and 5M-E engines.
- Remove the rubber cap from the idle adjusting connector and short both terminals of the connector with a wire.
- While the connector is still shorted, run the engine at 2500 rpm for two more minutes.
- With the engine at idle and the connector still shorted, read and record the voltage shown on the voltmeter.
- Remove the short circuit wire from the connector and then race the engine to 2500 rpm once.
- Adjust the idle mixture adjusting screw until the median of the indicated voltage range is the same as the reading taken in Step 8.
- Replug the idle mixture adjusting screw hole. Disconnect the tachometer, the voltmeter and the special wiring harness. Replace the rubber cap to the service connector and the idle adjusting connector.
See Figure 8
- Make sure that the air cleaner is installed properly, all air intake system pipes and hoses are connected, all vacuum lines are connected properly.
- Make sure that all EFI system wiring connectors are fully plugged.
- Run the engine until it reaches normal operating temperature, switch off all accessories and put the transmission in Neutral. Turn off the engine.
- Connect a tachometer to the engine. Be sure to connect the positive (+) terminal of the tachometer to the negative (-) terminal of the ignition coil or else damage to the igniter will result.
Not all tachometers are compatible with this ignition system, it is recommended that you check with the manufacturer before using a particular tachometer.
- Restart the engine and run it at 2,500 rpm for about 2 minutes.
- Remove the plug and turn the idle speed adjusting screw until the idle speed agrees with the appropriate figure given in the Tune-Up Specifications chart.
- Recheck the idle speed once more and then disconnect the tachometer.
4M-E AND 5M-E ENGINES
See Figure 9
- Fully open and then return the throttle valve.
- The throttle valve should return to the idle position in approximately 3.5 seconds.
- To adjust the return time, loosen the locknut and turn the adjusting bolt.
See Figures 10
- Warm the engine up to operating temperature.
- Connect a tachometer and check the idle speed. Adjust if necessary.
- Have an assistant run the engine up to 2,500 rpm on the 22R-E, or 3,000 rpm on the 5M-GE and hold it there. Pinch the vacuum hose between the dashpot and the vacuum transmitting valve (VTV).
- Release the throttle valve. See that the engine speed drops to 2,000 rpm and check that the dashpot is set. If the engine speed does not remain at 2,000 rpm, adjust the dashpot with the adjusting screw and locknut.