Adjusting engine idle speed (VW Passat B4)

Before adjusting the engine idle speed, perform the following operations:

warm up the engine (oil temperature not less than 80X);
check and, if necessary, adjust the gaps between the spark plug electrodes, check the initial ignition timing;
make sure that the power consumers, including the air conditioner (if there is one), turned off;
if the fuel lines are disconnected from the injectors, after connecting them, increase the crankshaft speed several times to 3000 rpm, then let the engine idle for at least 2 minutes;
make sure that when you turn on the ignition, a vibrating sound is produced;
make sure the air filter element is clean;
check whether the throttle valve opening is set correctly. The electric fan of the cooling system should not turn on during adjustment.

To adjust the engine crankshaft speed at idle:

disconnect connector 2 (fig. 2-176) ignition coils;
connect the tachometer according to the operating instructions;
disconnect the crankcase ventilation hose;
start the engine and check the engine idle speed, which should be within 950-1050 rpm;
if necessary, set the required idle speed of the crankshaft using the idle speed adjusting screw (fig. 2-177), located on the throttle body.

if necessary, set the required idle speed of the crankshaft using the idle speed adjusting screw…

After adjustment, connect the crankcase ventilation hose and connect the ignition coil connector.

To adjust CO in exhaust gases:

connect the gas analyzer and control tachometer according to the operating instructions;

Note: When adjusting the CO content, do not push or pull the adjusting screw. After inserting the socket wrench into the screw head, do not press the accelerator pedal to avoid damaging the adjusting screw.

start the engine at idle speed and check the CO content, which should be within 0.5-1.5%;
if there is a deviation from the norm, remove the plug of the mixture quality adjusting screw located between the fuel dispenser and the air supply cap of the air flow meter (fig. 2-178);
using a socket wrench for screws with an internal recess for a "3" key (fig. 2-179) turn the mixture quality adjustment screw until the CO content is within 0.5-1.5%. When turning the screw clockwise, the CO content in the exhaust gases increases, and vice versa.