A faulty thermal time switch will cause difficulties with cold starting.
Examination
When checking, the engine must be cold, the coolant temperature below 30°C. If necessary, remove the thermal time switch and cool it in a water bath.
Disconnect the high voltage wire - terminal 4 - on the ignition distributor (central cable) and short it to ground. If necessary, use an auxiliary cable of the same cross-section.
Disconnect the cold start valve plug and connect a voltage tester or test lamp to the plug contacts. The thermal time switch is tested through the cold start valve connector.
Turn on the starter for 10 sec. The LED of the test device should light up for 1-8 sec. depending on the temperature of the thermal time switch. The time of the first switch-on depends on the air temperature and should be within the permissible limits, see the diagram. For example, the coolant temperature is +10°C, the switch-on time is 2-2.5 sec.
If the tolerance is not met, replace the thermal time switch.
Connect the high voltage wire with the ignition distributor plug to the cold start valve.
Removal
Disconnect the plug on the thermal time switch.
Unscrew the switch.
Installation
Screw on the thermal time switch and connect the plug.
Check the coolant level and top up if necessary.
Diagram for the temperature and time sensor for a 5-cylinder engine