Operation of the Variable Catalyst

COLT/LANCER engines since September 1988 (and since September 1986, by special order) equipped with a variable catalyst. A controlled catalyst, in turn, requires the use of a controlled blending method.

Variable mixture preparation refers to a certain design of the carburetor or injection device, in which the ratio of fuel and air can always change depending on driving conditions and the oxygen content in the exhaust gases. Previous carburetors did not give this opportunity, as they did not have a corresponding control element. For this reason, engineers returned to the idea of an electronically controlled carburetor or injection device.

The mixer receives commands from a lambda probe located in the muffler in front of the catalyst and flowing around with exhaust gases. The lambda probe is an electrical sensitive element that converts information about the residual oxygen content in exhaust gases into electrical oscillations and provides the ability to correct the composition of the air-fuel mixture. In fractions of a second, the lambda probe transmits the corresponding signals to the control unit of the injection device, which constantly monitors the composition of the air-fuel mixture. This is required on the one hand because operating conditions are constantly changing (idle, full throttle), and, on the other hand, also because the afterburning of gases occurs in the catalyst if the engine exhaust still contains a sufficient proportion of gasoline.

In order for afterburning to occur in the catalyst at temperatures between 300°and 800°C, the air-fuel mixture must contain a larger proportion of fuel than would be required for clean combustion.

Commonly used catalysts are so-called ternary catalysts. This means that due to lambda control, carbon monoxide is simultaneously oxidized (SO) and hydrocarbons (NS), as well as a decrease in the content of nitrogen oxides (NO_X).