Turn on the ignition and check for control current. Otherwise, measure the resistance of the regulator. It should be 17.5-21.5 Ohm.
Connect the CO measuring device to the measuring pipe in the engine compartment. The measuring pipe is welded to the muffler inlet pipe and is usually closed with a blue cap.
Caution: Fit the measuring instrument hose tightly onto the measuring pipe. Make sure there are no leaks in the exhaust system.
Start the engine and let it idle.
Attention: During inspection and adjustment work the radiator fan must not operate.
Check the speed. The nominal value is 800-1000 rpm. If there is a deviation, adjust the speed to 900+30 rpm with the adjusting screw "A".
Check the control current. Its value should be between 4 and 16 mA.
Check the CO content using a special device. Nominal: 0.3-1.2% of the volume.
Note: If the CO content exceeds 1.2% at a control current of 4-16 mA, external causes should be sought. For example, the ignition system is faulty or out of adjustment, the exhaust system is loose, the injection valves are loose or loose, the fuel metering device is faulty and because of this, the amount of fuel at idle varies.
If the control current is outside the permissible range, adjust it even with normal CO content.
Remove the CO adjustment screw plug. To do this, drill a 265 mm hole in the plug with a drill, then screw a 3 mm screw into the plug and remove it together with the plug using pliers.
Set the control current to 10 mA with the adjusting screw CO "B". This will require a 3 mm long key.
Caution: When adjusting CO, do not press or lift the adjusting screw with the key. Do not apply gas when the key is inserted. After each operation, remove the adjusting key and apply gas briefly before reading the control current and CO content.
Check the idle speed again and measure if necessary.
Place the crankcase ventilation hose on the cylinder head and secure with a clamp.
Note: If the CO content now increases, this is not due to incorrect CO adjustment, but due to enrichment of the mixture from the crankcase due to dilution of the oil by gasoline during short trips in cold weather.
During a long trip, the fuel content in the oil decreases and CO is normalized. This can be quickly achieved by taking a 30-minute trip or changing the oil.
Put the cap on the box with activated carbon.
Turn off the measuring instruments when the ignition is off.
Reconnect all removed hoses.