Audi A4, S4

since 2000 of release

Repair and car operation

Catalytic converter

The catalytic converter has the central ceramic part of a cellular design-3-covered with a layer of the carrier. On a layer of the carrier there are the salts of precious metals operating as converters. The catalytic converter is fixed in the case-1-by means of the insulating basic layer-2-compensating at the same time thermal expansions of the catalytic converter (address to an illustration the Arrangement of elements of system of injection in a compartment of the diesel engine of 2.5 l).

Petrol engines

To reduce by means of the catalytic converter harmful emissions, systems of injection should dose out precisely amount of the injected fuel necessary for combustion. The lambda probe is in a reception pipe in front of the catalytic converter and is washed by a stream of the fulfilled gases. The lambda probe represents the electronic sensor measuring the content of oxygen in final gases and representing its type of fluctuations of tension. Information from a lambda probe is transferred to the control unit of system of injection. The received value allows to regulate structure of an air-petrol mix. On the one hand it is necessary, as service conditions (the idling, full gas), on the other hand, constantly change as optimum reburning of fuel in the catalytic converter occurs only in this case if final gases contain fuel enough.

That in the catalytic converter there was a fuel reburning, it is necessary to have temperature 300 - 800°С. For this purpose the bigger content of fuel in a mix, than for pure burning is necessary.

The catalytic converter of the petrol engine represents the so-called three-functional device. In adjustable process of transformation oxidation of an oxide of carbon (WITH) and hydrocarbon (NANOSECOND), and also reduction of concentration of oxides _{of nitrogen (NOx)} is carried out.

Security measures for an exception of damages of the catalytic converter

For an exception of damages a lambda probe and the catalytic converter it is necessary to fulfill the following requirements:

Petrol engines

Surely apply only unleaded gasoline. Start of the heated-up petrol engine by pushing or towage is authorized to carry out only in one attempt and at distance no more than 50 m. Better for this purpose to apply a starting cable. Not burned down fuel at ignition can lead to an overheat of the catalytic converter and its destruction.

At difficulties with start of the engine it is not necessary to include a starter too long. Continuous injection of fuel is thus made. It is necessary to reveal and eliminate a cause of defect. If there are malfunctions with ignition system, at determination of their character it is necessary to exclude fuel injection at starter inclusion. For this purpose disconnect the relay of the fuel pump. Never spend fuel in a fuel tank completely. At emergence of interruptions in ignition do not raise number of turns of the engine and immediately eliminate malfunction. Apply only the recommended spark plugs. Do not carry out spark check with the disconnected shtekerny connection of a spark plug. Carrying out check of operation of the cylinder by disconnection of a wire of ignition from its candle is not allowed. Thus not burned down fuel gets to the catalytic converter.

Petrol and diesel engines

Do not stop the car over dry foliage or a grass. The system of production of the fulfilled gases around the catalytic converter very hot also radiates heat even after an engine stop. Do not put on elements of system of release of means for protection of the bottom of the car. It is not allowed to change a design of heat-shielding screens. When filling engine with oil especially pay attention to exceeding at all the level designated on the index as by Max. Excess of oil owing to incomplete combustion arrives in the catalytic converter and can damage its covering from the alloyed metal or completely to destroy the catalytic converter.