Faulty cold start valve causes starting difficulties (cold and warm), transient dips and high fuel consumption.
The thermal time switch limits the fuel injection time depending on the engine temperature.
Withdrawal
Disconnect the plug from the cold start valve.
Unscrew the fuel line to the cold start valve.
Attention: The system is under pressure, so put a rag on the connection and slowly loosen the bolt. If the cold start valve is removed only for inspection, the fuel line remains connected.
Unscrew the cold start valve and remove it from the inlet elbow.
Examination
Disconnect central high voltage cable -terminal 4- from ignition distributor and connect to ground. If necessary, use an auxiliary cable of the same size.
Disconnect the plug from the thermal switch.
Connect the green-white wire of the thermal time switch to ground with the auxiliary cable.
Attention: Do not ground the black-red wire. Possible short circuit!
Disconnect the plug from the cold start valve and connect a voltmeter or indicator to the contacts of the plug.
Turn on the starter, the indicator should show voltage. otherwise, find and fix the break according to the scheme.
Engines 113/115/136 hp, designations 3A, AAD, NG
The injection time of the cold start valve is determined by the KE-Jetronic/-Motronic control unit as a function of the engine temperature.
NG: Disconnect the plug from the coolant temperature sensor and short both contacts of the plug to ground through a 3 kΩ resistor. The injection jet of the valve should have a cone shape, the injection time should be 2-3 seconds.
3A, AAD: Disconnect the plug of the coolant temperature sensor and connect both pins of the plug through a 15 kΩ resistor. The injection jet should be cone shaped and the injection time should be 8 seconds.
If the valve does not inject, disconnect the plug on the cold start valve and check the resistance between the contacts. Rated value: 10 Ohm.
If the resistance of the valve is in order, connect a voltage indicator to the plug and turn on the starter. The indicator should be on for 8 seconds. Otherwise, have the control unit checked and replaced if necessary.
Connect the plug to the cold start valve, the fuel hose is connected.
Lower the cold start valve into the measuring vessel.
Switch on the starter for a short time. The injection jet must have the shape of a regular cone.
Wipe off the valve nozzle.
Within a minute, not a drop should stand out from the valve. The outside of the valve must also be dry.
Installation
Install cold start valve with new seal and screw on.
Connect the plug to the thermal time switch.
Fit ignition cable -terminal 4-.
If removed, screw fuel hose to cold start hose with 10 Nm. Connect plug.
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