Lambda Testing W/ Volt, Dwell, RPM and CO Meter

Fig. 70 DISCONNECT LAMBDA SOND:

1. Disconnect Lambda sond. Fig. 70.

Fig. 71 CONNECT DWELL METER:

2. Connect a dwell meter:
3. Connect red wire to the test point.
4. Set meter for reading of a "4-cylinder" engine. Fig. 71.

NOTE:
The dwell meter must have a minimum measuring range of 70°.
Instruments such as the "Volvo Mono-Tester" and "Sun" testers of later design are recommended.

Fig. 72 CONNECT MEASURING INSTRUMENTS:

Connect measuring instrument:
5. Connect tachometer.
6. Connect CO meter to the probe port in the exhaust pipe upstream of the catalytic converter. Fig. 72.

Fig. 73 CHECK IDLE-SPEED AND CO-CONTENT:

7. Warm up engine.
8. Wait for at least 5 minutes after the engine has reached operating temperature, then carry out the next step.
9. Check idle speed and CO content Fig. 73. (see "SPECIFICATIONS" > "MECHANICAL SPECIFICATIONS").
10. Adjust if necessary.

Fig. 74 CHECK LAMBDA SOND FUNCTION:

Check Lambda sond function:
10. Connect Lambda sond to dwell meter and CO meter. Fig. 74.
11. Check reading.
12. Dwell meter reading should change slightly, usually drop when sond is connected. CO level should drop to less than 1.0%.

Fig. 75 CHECK LAMBDA SOND FUNCTION:

If neither CO content nor meter reading changes:
-Disconnect Lambda sond and ground the wire. CO content and dwell angle should increase. Fig. 75.
-Wiring and control unit are O.K. if meter reading increases.
-Replace and re-test with new Lambda sond.
- If meter reading does not change, either control unit or wiring to control unit is defective. Check wiring to control unit, if O.K. replace control unit.

C.O. content and dwell meter reading increase:
-This indicates a defective Lambda-sond (internal short). Replace and re-test with new Lambda sond.