The fuel injection system receives control signals from the lambda probe, which is located in front of the catalytic converter in the exhaust pipe and is washed by the flow of exhaust gases. The lambda probe is an electrical measuring sensor that indicates the residual oxygen content in the exhaust gases by voltage fluctuations and allows you to draw a conclusion about the composition of the air-fuel mixture. Within a fraction of a second, the lambda probe transmits the corresponding signals to the fuel injection system control unit, constantly changing the air-fuel mixture ratio. On the one hand, this is required as a result of constantly changing operating conditions (idle, full throttle), on the other hand, due to additional combustion of fuel in the catalyst, since the exhaust gas still contains a sufficient amount of it.
In order for the fuel to burn out in the catalytic converter at temperatures from +300° to 800°C, the air-fuel mixture must contain a greater proportion of gasoline than is required for clean combustion. As a result, a car with a catalytic converter has a 5% higher fuel consumption.
The catalytic converter is located in place of the additional muffler under the bottom of the car. The catalytic converter consists of a ceramic honeycomb-shaped body coated with platinum or radium. The fragile ceramic body is placed in an elastic heat-resistant wire cloth.
The installed conventional catalyst is a 3-way catalyst. This means that such a catalyst, thanks to lambda regulation, simultaneously oxidizes carbon monoxide (CO) and hydrocarbons (HC), as well as reduces the content of nitrogen oxide (NOx).
In order to avoid damage to the lambda probe and catalytic converter, it is imperative to take into account the following instructions:
- fill up with unleaded petrol only;
- starting the engine by towing or pushing is not allowed: unburned fuel can lead to overheating of the catalytic converter and its failure. It is necessary to use a second battery;
- frequent repetition of cold starts should be avoided. Since unburned fuel accumulates in the catalyst, it burns explosively when ignited and leads to the catalyst failure;
- if the starter is poor, do not turn on the starter for a long time unless necessary. Find and fix the problem;
- if there is no ignition in some cylinders, avoid high engine speeds. If there is no ignition in any cylinder (when testing the engine) unburned fuel enters the catalyst;
- do not park the car over dry leaves or grass. The exhaust system in the area of the catalytic converter has a high temperature;
- when filling or topping up engine oil, be especially careful that under no circumstances is the oil filled above the "max" mark on the oil level indicator. Excess oil, due to incomplete combustion, will get into the catalyst and can destroy it.
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