Air/Fuel Mixture: Adjustments

NOTE: Engine must be in perfect working order. All accessories should be switched OFF during adjustments. Adjustments should be made as quickly as possible to keep intake passages from heating up which would produce incorrect readings. Air cleaner should be fitted during adjustments.

Exhaust Gas Test Connection:

1. Fit exhaust gas adaptor.
2. Locate oxygen sensor connector at upper air injection pump mount and disconnect it.

Air Injection Hose:

3. Disconnect hose from air injection pump to diverter valve and plug.
4. Run engine to operating oil temperature (185 - 203° F, 85 - 95° C).
5. Measure CO%. If valve is not within specified range at 1000 ±50 rpm, reset adjustment at mixture control unit.

Mixture Adjustment:

Place special tool 9156 into spring-loaded or fixed allen key, in mixture control unit. Press down tool approximately 18 mm to allow spring-loaded allen key to engage mixture control screw. Turn screw clockwise for richer mixture: counter-clockwise for leaner mixture. (Right is rich: Left is lean).

CO% value
1.0 ±0.2 % 1000 ±50 rpm

6. Reconnect oxygen sensor connector.

Idle Screw Adjustment:

7. If idle speed changes, reset to:

1000 ±50 rpm
8. Refit air injection hose.
9. Remove exhaust adapter, refit plug, and tighten to:

11 ft lb (15 Nm)

10. With system tester 9288, check pulse/duty factor (regulating mode) in "Special Functions" menu. Specified value is:

20% - 80%