Concepts related to exhaust gases

Carbon monoxide (SO): measured by examining the composition of exhaust gases Precise control of the amount of injected fuel, homogeneous mixing of the air-fuel mixture in the intake tract and combustion chamber, as well as correctly set ignition timing are the main conditions for low CO concentration in the exhaust gases. Never measure CO indoors - risk of suffocation! In the atmosphere, carbon monoxide mixes with oxygen to form harmless carbon dioxide (CO2). CO2 plays a significant role in the formation of the greenhouse effect.

hydrocarbons (CH): are formed only during incomplete combustion in cold places and rugged combustion chambers. The proportion of hydrocarbon depends on the design of the engine (immutable value), but too rich or too lean mixture increases the proportion of CH in the exhaust gases. Together with nitrogen oxides (NOX) hydrocarbons are responsible for the formation of smog (difficult to decompose concentration of exhaust gases in the atmosphere).

nitrogen oxides (NOX): their proportion increases at high combustion temperatures. For example, in engines (engines running on depleted working mixtures), which are designed taking into account the reduced output of CO and CH (reduced fuel consumption). At high concentrations, NOX can irritate the respiratory system. When combined with water, they form nitric acid (acid rain).

Sulfur dioxide (SO2): It is formed mainly during the combustion of diesel fuel due to the sulfur content in it. Under the influence of light, sulfuric or sulphurous acid is formed. Both compounds contribute to acid rain. The intensification of traffic currently affects the formation of approximately 3% of sulfurous acids.

Typical poisons in diesel exhaust gases: the diesel engine emits a small amount of CO and CH, which is due to the principle of its operation. Despite higher compression, a diesel engine also emits less nitrogen oxides than a gasoline engine. But diesel engines are guilty of producing other problematic combustion products. For example, soot is a typical component of spent diesel fuel. Soot is made up of unburned carbon particles and ash. Sulfur dioxide is formed during the combustion of diesel fuel, also in a higher concentration than in a gasoline engine (see sulfur dioxide).

Special Exhaust Gas Test (ASU): mandatory in Germany for all passenger cars since December 1993. Cars over 30 years old may be exempt from ASU. On new vehicles, the ASU mark is valid for 3 years, after which a mandatory check is made every 2 years. ASU carry out repair shops with the appropriate equipment, as well as DEKRA and ZOV. When measuring, the exhaust system must be leak-tight and the suction system must be in perfect working order. If your Focus is undergoing regular maintenance, then ASU is done there automatically.