Audi A4

since 1994 release

Manual of the car

Six-cylinder engine

The device of automatic preliminary heating of the soaked-up air is from the entrance party of the case of the air filter. It is faced by a problem of the support of favorable air temperature which is soaked up by the engine.

For this purpose there is the following reason: at cold weather fuel-air mix is sated more if the soaked-up air moves previously heated. The same amount of warm air occupies the bigger volume, than cold air. As the engine can soak up only certain amount of air, at the included preliminary heating a little less air arrives – mix becomes richer, fuel consumption increases. It is necessary for trouble-free operation of the engine only at low temperatures.

Functioning

The gate of preliminary heating of the soaked-up air is adjusted by the thermostat which completely opens supply of warm air at a temperature of -20 °C. At temperature increase the gate is slowly closed until at a temperature of +5 °C it is not closed completely.

Violations in work

If preliminary heating of air functions unsatisfactorily, then it can lead to operational violations.

In cold season:

• Unstable idling after start of the cold engine at a warming up stage.
• Bad switching, the engine it is inclined to interruptions.

In warm season:

• The lowered power, is not reached the maximum speed.
• The increased fuel consumption.

Check of preliminary heating of air

Six-cylinder engine