1.The working principle of the catalytic converter
When the high-temperature automobile exhaust gas passes through the purification device, the purification agent in the catalytic converter will enhance the activity of the three gases CO, hydrocarbons and NOx, and promote certain oxidation-reduction chemical reactions, in which CO is oxidized at high temperature It becomes colorless and non-toxic carbon dioxide gas; hydrocarbons are oxidized to water (H20) and carbon dioxide at high temperature; NOx is reduced to nitrogen and oxygen. Three kinds of harmful gases become harmless gases, so that car exhaust can be purified. The premise is that oxygen is available and the air-fuel ratio is reasonable.
2.Common fault performance of catalytic converter
If one day you feel that your car's fuel consumption is soaring, then you should see if the three-way catalytic converter on your car is out of order. The three-way catalytic converter is an important device used to control harmful gas emissions. Due to the harsh working environment, the catalytic converter will inevitably experience blockages and other failures after a period of working time, which will not only lead to increased fuel consumption of the car, but also It will also reduce some of the power of the car.
Generally speaking, the working life of a catalytic converter is divided into regions. In developed countries and regions such as the United States, Japan, and Europe, the service life of a catalytic converter on a car is generally 100,000 to 200,000 kilometers, but the service life of a catalytic converter in China is average. Only 30,000 to 50,000 kilometers. This is because China has a large population and it is not difficult for most people to buy a car, so there will often be congestion on the road, which is also the main cause of catalyst damage, blockage, and carbon deposits. one.
Catalytic converter failure is generally the most common cause of exhaust emissions exceeding the standard. It is easy to understand from the working principle that has been known before. The catalytic converter is blocked, and harmful gases such as CO, HC, NOx, etc. are not treated and passed through the exhaust system. If it is released, it will definitely exceed the standard. In addition, fuel consumption will also increase, because when the catalytic converter fails, it will further affect the normal operation of the oxygen sensor, so that the fuel injection, air intake and ignition cannot be accurately controlled, so fuel consumption will increase.
There is also a decrease in power. This phenomenon is most obvious for cars with increased turbos, because when high-pressure exhaust is required, the exhaust is not smooth due to blockage, which affects the intake volume, and finally causes the engine power to drop. Finally, There will be feelings of weakened power and lack of energy to refuel. There is also an uncommon situation, that is, the engine shakes and often stalls. This situation only occurs when the catalytic converter is completely blocked. Because the exhaust gas cannot be discharged, it will inevitably cause back pressure and reverse flow, which will cause the engine to shake, Breathe until the flame goes out.
If the above situation occurs, it is recommended that the car owner go to a professional repair shop for inspection immediately. If it is determined that the damage cannot be repaired, it is the best choice to replace the catalytic converter as soon as possible.
3.Causes of blockage of catalytic conversion
1. Internal factors:
The noble metal catalyst on the catalytic converter supports sulfur, phosphorus and carbon monoxide. Molecules such as incomplete combustion, lead and manganese have a strong adsorption effect, and it is easy to form complex chemical complexes. At the same time, the precious metal catalyst has a strong oxidation catalysis, which makes the adsorbed gasoline incompletely combusted more easily oxidized, polycondensed, and polymerized to form colloidal carbon deposits, causing the catalytic converter to block.
2. External factors:
1. Gasoline: Gasoline has high sulfur content, which can easily form chemical complexes in the catalytic converter and cause blockage. The oil is of poor quality, and more gasoline is easy to cause blockage of the catalytic converter.
2. Engine oil: Long-term use of engine oil containing sulfur and phosphorus antioxidants is likely to cause blockage of the catalytic converter.
3. Roads: As cars produce a lot of incomplete combustion under conditions of acceleration and deceleration, long-term driving on congested roads is likely to cause blockage of the catalytic converter.
4. No disassembly, cleaning and maintenance of fuel injection nozzles and air intake: Because a large amount of colloidal carbon deposits will be washed down during the cleaning process. Therefore, it is easy to cause blockage of the catalytic converter, which is also the reason for the increase in fuel consumption of some vehicles after the "no-disassembly cleaning and maintenance of fuel injectors and intake ports".
5. Turbocharging: Vehicles with turbocharging are prone to blockage of the catalytic converter, which is mainly caused by incorrect operation of the driver.]
4.How to detect whether the catalytic converter is blocked
1. Remove the air filter, step on the accelerator on the spot, and check whether the air filter emits black smoke. If so, it means it is blocked.
2. Feel the temperature difference between the front and rear of the three-way catalytic converter and judge whether it is blocked. A large temperature difference indicates blockage;
3. Check whether the voltages of the oxygen sensors before and after the three-way catalytic converter are consistent. If they are consistent, it means that the three-way catalytic converter is damaged.
4. Reach out to the exhaust pipe to see if you can feel the airflow. If you can't feel it, it means blockage.
5.Failure to reach the maximum speed and poor acceleration during the test run may also be a sign of clogging of the three-way catalyst.
