Idle speed and carbon monoxide content in exhaust gas

PROCEDURE

Due to the complexity of the fuel injection system, it is not recommended to adjust the engine idle speed and the CO content in the exhaust gases yourself. It is better to carry out the adjustment at Volkswagen service stations that have the necessary special equipment. Check and adjust the engine only when it is warm, with the ignition timing correctly set and the exhaust system in good condition. PROCEDURE 1. Start the engine and let it idle until the oil temperature reaches 80°C. Make sure the coolant temperature does not exceed normal, since the cooling fan must be switched off during the check and adjustment. 2. Switch off the engine and turn off all electrical consumers (headlights, radio, air conditioning, etc.). 3. Disconnect the crankcase ventilation hose and plug it. 4. Connect the test tachometer and the gas analyzer. 5. Start the engine and let it idle. If the fuel lines were disconnected from the injectors or replaced with new ones before checking and adjusting the idle speed, raise the speed to 3000 min⁻¹, then let the engine idle for 2 min before starting the check and adjustment. 6. Check the idle speed. It should be within 900–1000 min⁻¹ for vehicles built up to 09.1984, 800–1000 min⁻¹ for vehicles built from 09.1984, and 850–1000 min⁻¹ for vehicles equipped with air conditioning. If the speed differs from the specified value, adjust it with screw 20 (see Fig.

Air filter and engine intake pipe with fuel injection system). 7. Check the CO content in the exhaust gases. It should be 0.5–1.5%. If the CO level differs from the specified value, adjust it. To do this, remove the plug from the housing of air flow meter 4 and adjust the CO content in the exhaust gases with screw 5. To increase the CO content, turn screw 5 clockwise; to decrease it, turn counterclockwise.

Do not press on the screw while turning it: this may move the air flow meter plate and affect the adjustment. 8. Remove the tool from the opening in the housing of air flow meter 4 and increase the engine speed for a few seconds. Do not increase the engine speed if the tool for turning screw 5 has not been removed from the housing of air flow meter 4, as it may become jammed in the housing. Check the CO content in the exhaust gases. 9. Check and, if necessary, adjust the idle speed.