240 L4-2.3L SOHC VIN 88 B230F (1986)
If test diode remains ON = CO is too high (rich air/fuel mixture).
If test diode remains OFF = CO is too low (lean air/fuel mixture).
Adjusting CO
CO should only be adjusted after all possible faults have been checked/rectified.
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Turn off engine.
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Drill two 2 mm (0.08 in.) holes in plug.
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Withdraw plug with circlip pliers.
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Start engine.
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Adjust CO content. CO screw should be turned until test diode starts to flash.
Counterclockwise reduces CO
Clockwise increases CO
Adjustment range = 15 turns.
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Seal CO adjustment screw
Always use a new plug.
