CO-Adjustment

Fig. 250 AIR-FUEL CONTROL UNIT:

CO content should be checked at test plug upstream of catalytic converter. Initial CO-adjustment is made at the factory and should not need to be changed. The access hole to the CO-screw is sealed with a steel ball. Fig. 250 If CO is not within specifications (see emission sticker or "SPECIFICATIONS"), and all other causes for incorrect CO readings have been checked, follow the adjustment procedure as described below.

Fig. 268 DISCONNECT FUEL LINES AT AIR-FUEL CONTROL UNIT:

1. Disconnect battery ground cable.
2. Disconnect all fuel lines Fig. 268. at air-fuel control unit. Be careful not to allow dirt to enter air-fuel control unit.

Fig. 269 REMOVE AIR-FUEL CONTROL UNIT:

3. Remove air-fuel control unit. Fig. 269.

Fig. 270 REMOVE STEEL BALL:

4. Turn air-fuel control unit upside down and punch out steel ball with a 3 mm slightly bent punch. Fig. 270.

Fig. 268 DISCONNECT FUEL LINES AT AIR-FUEL CONTROL UNIT:

5. Reinstall air-fuel control unit. Fig. 268.
6. Reconnect all fuel lines using new copper washers.
7. Reconnect battery ground cable.

Fig. 386 DISCONNECT LAMBDA SOND (OXYGEN SENSOR):

8. Disconnect Lambda sond (oxygen sensor) at wire connector. Fig. 386.

Fig. 411 REMOVE CO TEST PLUGS:

9. Remove test plugs at header pipes. Fig. 411.

Fig. 412 CONNECT CO TEST EQUIPMENT:

10. Connect CO-meter and tachometer. Fig. 412.
11. Run engine to operating temperature and five minutes beyond.
12. Check idle speed with air conditioner off (750 ± 20 RPM). Idle speed is controlled by an electronic control unit (ECU). Adjust idle speed only if it is out of specified tolerances, see "IDLE SPEED".

Fig. 387 CO ADJUSTMENT:

13. Check and adjust CO content. CO content can be 0.7 - 1.3 %, set CO to 1.0 % if adjustment is necessary. Fig. 387. Use VOLVO tool #5102 or equivalent. Cover the adjusting hole and rev the engine briefly between adjustments, when taking CO readings.
14. Reconnect Lambda sond (oxygen sensor). CO should drop below 1.0 %.
15. Recheck idle speed (750 ± 20 RPM).

Fig. 388 INSTALLING STEEL BALL INTO AIR-FUEL CONTROL UNIT:

16. Reinstall the steel ball into air-fuel control unit using VOLVO tool #5232 or equivalent. Use a light hammer to tap ball into position. Fig. 388.
17. Remove all test equipment and reinstall the exhaust pipe plugs.