Turn off all electrical consumers. If available, then the air conditioning system.
Connect the crankshaft speed meter.
Attention: Connect the device only when the ignition is switched off.
Check ignition timing.
Connect the device for measuring the CO content. In vehicles with a catalytic converter, connect the device to the CO sampling pipe in the engine compartment. The sampling tube is located on the outlet and is usually closed with a blue cap.
Caution: Push the hose of the measuring device firmly onto the sampling tube. Ensure that there is no leakage.
Check if the air damper is fully open (top carburetor choke). If necessary, adjust the automatic fuel mixture enrichment device at start-up or ensure the mobility of the damper. To do this, unscrew the intake air guide cover, and then put it back in place.
Disconnect the crankcase breather hose from the cylinder head and lay it so that it can only take in fresh air. Before removing, bite the hose clamp with side cutters.
Start the engine and let it idle. Check idling speed and CO content.
Prescribed values: speed - 800±50 1/min; CO content - 1.0±0.5% by volume.
Adjustment
Remove the protective cap from the CO adjustment screw.
Set the prescribed values by turning the idling speed adjusting screws -A- and the CO content -B- alternately.
Attention: During the adjustment process, the cooling fan must not rotate.
Disconnect measuring devices with the ignition off.
Put the blue rubber cap on the CO sampling tube.
Close the CO content adjustment screw with a protective cap.
Connect the crankcase ventilation hose to the cylinder head and secure with a clamp.
Attention: If the CO content has now increased, then the reason is not an incorrect adjustment, but an enrichment of the combustible mixture due to the intake of gasoline vapors from the crankcase, where gasoline enters mainly when traveling short distances.
During long continuous trips, the proportion of gasoline in the engine oil decreases, and the CO content in the exhaust gases returns to normal. It can also happen quickly after a 30-minute drive or another oil change.
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