Air/Fuel Mixture: Testing and Inspection

Connect Test Instrument
- Tachometer.
- CO meter connected to exhaust pipe.





Conditions:
- Engine idling.
- No diagnostic trouble codes (DTCs) stored.
- Air conditioning (A/C) off.
- Automatic transmission: gear selector in P.
- Seal hose between canister purge (CP) valve and intake manifold with a hose clip.
- Seal crankcase ventilation with a hose clip.

NOTE: If the car is often driven in urban traffic (starting, idling etc.) the engine oil may be contaminated with fuel. Crankcase gases may affect CO adjustment.

- Run the engine to normal operating temperature. Run the engine at 1,500 rpm.

NOTE: The engine should be run until the coolant thermostat opens and then for a further 10 minutes.

- Check CO content.
- Check value = 0.5 - 2.0%
- Continue adjusting CO content if necessary.





Adjusting CO Content

Do not adjust CO content until all possible fault causes have been checked and remedied.

- Remove seal.
- Switch off the engine
- Drill two 2 mm (0.079 in) holes in the plug.
- Pull out plug with circlip ring pliers.
- Start the engine and idle it.





Adjust CO Content
- Adjust CO content to 1%.
- Turning adjustment screw:

- clockwise reduces the CO content.
- counter-clockwise increases CO content.
- The adjustment range is 15 turns.





Checking Voltage
- Adjust CO content to 1%.
- Engine idling.
- Go into scrolling values.
- Read off CO potentiometer value. Diagnostic trouble code EFI-211 will be stored after 20 seconds if this value exceeds 4.8 Volts or is below 0.2 Volts. This indicates that the engine is faulty.





Seal Adjustment Screw
- Seal CO content adjustment screw.
- Use a new plug.
- Tap the plug into place.