2.17.7.7. Operation of the cars equipped with the catalyst
Petrol VW T4 engines are serially equipped with catalysts. The catalyst demands that the engine used only unleaded gasoline (without the content of lead).
The system of injection of fuel receives signals of management from a lambda probe which is in front of the catalyst in an exhaust pipe and is washed by a stream of the fulfilled gases. The lambda probe is the electric sensor which specifies the residual content of oxygen in exhaust gases on fluctuations of tension and allows to make the conclusion about composition of air-fuel mix. During fractions of a second the lambda probe transmits the corresponding signals to the control unit of system of injection of fuel, constantly changing at the same time a ratio of air-fuel mix. On the one hand it is required as a result of constantly changing operational conditions (idling, full gas), on the other hand, because of additional combustion of fuel in the catalyst as exhaust gas contains still its sufficient quantity.
In order that, at temperatures from +300 ° to 800 °C in the catalyst fuel could burn down, air-fuel mix has to contain a big share of gasoline, than it is required for pure combustion. Thereof at the car with the catalyst fuel consumption is 5% higher.
The catalyst is located on the place of the additional muffler under the car bottom. The catalyst consists of the ceramic case in the form of honeycombs covered with platinum or radium. The fragile ceramic case is placed in elastic heat-resistant wire fabric.
The installed ordinary catalyst is the 3-running catalyst. It means that such catalyst thanks to a lambda adjustment at the same time has an oxidation of carbon monoxide (SO) and hydrocarbons (NANOSECONDS), and also reduction of maintenance of an oxide of nitrogen (NOx).
To avoid damage a lambda probe and the catalyst, it is insistently necessary to take the following instructions into account:
– to fill only unleaded gasoline;
– start of the engine towage or from a push are inadmissible: not burned down fuel can lead to an overheat of the catalyst and its exit out of operation. It is necessary to use the second accumulator;
– it is necessary to avoid frequent repetition of cold starts. As not burned down fuel collects in the catalyst, at ignition burns down vzryvoobrazno and conducts to a catalyst exit out of operation;
– at bad start not to include needlessly a starter for a long time. To find and eliminate malfunction;
– in the absence of ignition in some cylinders to avoid high turns of the engine. In the absence of ignition in any cylinder (when testing the engine) not burned down fuel comes to the catalyst;
– not to park the car over dry foliage or a grass. The exhaust system in the field of the catalyst has high temperature;
– during the filling or a doliva of engine oil especially to watch that oil was not filled in above tag "move" on the index of level of oil at all. Excess oil, because of incomplete combustion, will get to the catalyst and can destroy it.