Engine warm-up
During the warm-up of the Transporter T4 engine, after starting it at low temperatures, the engine
needs a richer mixture supply, because a certain amount of fuel settles on the walls of the combustion chamber.
Moreover, to compensate for the increased internal friction, the engine must generate more torque to maintain a constant idle speed. Under these conditions, it is necessary to supply the engine with an increased amount of rich mixture.
The increase in the amount of air supplied by the engine during idling is implemented using an additional air supply valve, which opens the air supply to the cylinders when the engine is cold, regardless of the throttle position.
The enrichment of the mixture for warming up the engine is implemented by the microprocessor module (based on information received from the temperature sensor) by a corresponding increase in the injection duration.