Air/Fuel Mixture: Adjustments

NOTE: Richness at idle is adjusted by measuring the voltage signal from the injection ECU.

1. Run the engine until normal operating temperature is reached.
2. Check to ensure the ignition timing is properly adjusted.
3. Check that the air filter is in good condition and in place on the vehicle.
4. Check to ensure the idle speed is 900 +50 rpm.

Test Terminal 22:

5. Connect a digital voltmeter to the connector #22, located along the right inner front fender, near the air filter assembly.
6. Disconnect the PCV hose from its fitting on the valve cover and plug it. Leave the fitting open to the atmosphere.
7. With the engine running the voltage should be 7.2 +/- 0.2 volts.
8. If the reading that is obtained is not within specification,

Mixture Adjustment Screw Location:

drill off center, with a (4.5mm) bit, into the central portion of the do not tamper plug on the air flow sensor to a depth of (5mm) maximum.
9. Screw a sheet metal screw into the plug and remove the plug.

Air Fuel Ratio Adjustment Screw:

10. Adjust the mixture screw to obtain the specified voltage noted in step 7. To enrich the mixture, gradually turn the screw clockwise. To lean the mixture turn the screw counterclockwise.
11. After each adjustment, reset the idle speed with the idle screw. If the voltage varies, repeat the adjustment.
12. Install a new do not tamper plug when all adjustments are completed.
13. Reconnect the PCV hose.