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Annual inspection of automobiles: contents of exhaust gas inspection and effective inspection methods-detailed explanation
2024-10-12
Exhaust detection is the annual inspection of old vehicles and automobiles."The most difficult", with the decline in the working conditions of the engine and exhaust purification system, excessive exhaust emissions are almost a "common problem". So what is the content of the car's exhaust gas being detected, and will the exhaust gas have a serious impact on air quality?
Analysis of Main Components of Exhaust Gas
- Carbon dioxide (CO2）
- Hydrocarbons (HC）
- Nitrogen oxides (NOx）
The above three substances are the main substances in the tail gas, followed by carbon monoxide, particulate matter, oxygen, etc.More than 200 substances. Among these substances, CO2 will produce greenhouse effect (global warming),HC will form highly toxic photochemical smog (carcinogenic),NOx will cause serious damage to the human visual system and respiratory system, and it is also the main substance of acid rain formation. The main components in these three exhaust gases need to be strictly controlled, otherwise the problems will be very serious.
The impact of exhaust gas is not alarmist. In the 1960 s and 1970 s, it appeared in Europe and the United States and other regions."Blue fog stage". In the early days when automobile exhaust was not controlled, the manufacture of internal combustion engines did not consider exhaust purification at all; as a result, the air quality in areas with large car ownership was seriously reduced, at least in the UK, due to "blue fog" (excessive exhaust emissions) caused a large area of respiratory diseases. After this stage, exhaust control standards for automobile manufacturing have emerged one after another, such as European standards, American standards, and national standards that began to be implemented in the 22nd century.
Two Factors Affecting Automobile Exhaust
It is well known that the products of full combustion of gasoline are carbon dioxide and water, followed by trace amounts of the above substances; a liter of gasoline can be completely burned to produce about 2.4 kilograms of carbon dioxide, and water will exceed 270 grams. However, the engine of a fuel vehicle cannot fully burn at all times, because the vehicle power will decline due to excessive cooling during the cold start heating process. In order to compensate for the power, the ECU needs to actively increase the speed and enrich the fuel injection to compensate the power.
However, the fuel injection volume at this stage is greater than the standard air-fuel ratio, and the impact is that the mixed oil and gas cannot be fully burned; this process will obviously cause excessive exhaust gas, especially hydrocarbons will exceed the standard, so the vehicle is detecting When the exhaust gas must be detected in a hot car, the air-fuel ratio can return to a normal state after the car is hot. However, some cars will not pass the test, because the thermostat of the vehicle is damaged and the heat engine speed is extremely slow. When the vehicle is tested in winter, it will even be in a cold car and enriched fuel injection state, and the exhaust gas will naturally exceed the standard. Therefore, it is necessary to check whether the engine can heat up normally before the inspection to prevent the thermostat failure from affecting the inspection.
To sum up, before each cold start of the car, there will be a state of insufficient combustion of "enriched fuel injection" for more than ten minutes. This stage will not only cause the exhaust gas to exceed the standard, but also produce free carbon and form carbon deposits. These carbon deposits will accumulate and adhere to the engine's fuel injectors, spark plugs, throttles, oxygen sensors, etc., and their effects will cause poor fuel injection atomization, poor ignition intensity, insufficient air intake, or fuel injection calculation In other situations, the final result is that the exhaust gas will continue to be out of balance due to continuous "insufficient combustion" due to carbon deposits. Therefore, it is necessary to check the degree of "carbon pollution" of the engine before testing the vehicle. If the vehicle has obvious increased fuel consumption, unstable idling, idling resonance, etc., it will be very difficult to pass the customs without cleaning up the carbon deposits.
Focus: It is necessary to check the three-way catalytic converter for old vehicles. The so-called ternary means that the catalyst uses the "platinum, rhodium and palladium" sprayed in the filter element as a catalyst to react with HC/NOX/CO in the engine exhaust and decompose it into relatively harmless oxygen, carbon dioxide and water. If the three-way catalytic converter is damaged or blocked, the exhaust gas will inevitably exceed the standard, and the carbon deposits generated by the engine will always slowly block the filter element of the catalytic converter; therefore, after checking the engine working conditions, the only reason why the exhaust gas cannot pass is that the catalytic converter has problems. The solution is to disassemble and soak in cleaning agent.
Summary: It is good to understand the relevant knowledge about automobile exhaust. Reduce the wrong in-situ heating of the car during the daily use of the car. After the vehicle reaches a high temperature (the middle line of the water temperature gauge), you can appropriately pull a few feet of speed, which will prevent and clean up carbon deposits. Very ideal effect. Secondly, if there is no confidence in the working conditions of the vehicle during the annual inspection, mixing 30% ~ 50% anhydrous ethanol in the fuel will be easier to overcheck, because the combustion products of fuel ethanol are only carbon dioxide and water, which is also the reason why E20 ethanol gasoline will be popularized. However, excessive addition will damage the oil system. After testing, ordinary gasoline should be added for mixing and dilution for reference.
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