Lishi throttle cleaning

Engine exhaust contains harmful gases such as carbon monoxide (C0), hydrocarbons (HC) and nitrogen oxides (NOx), and the three-way catalytic converter is a conversion device that can convert these three harmful gases into harmless substances. The three-way catalytic converter is installed in the exhaust pipe and looks like a muffler. Its outer cylinder is made of double-layer stainless steel plate, and the interlayer is filled with thermal insulation material-asbestos fiber felt. There are high-temperature resistant ceramic carriers in the steel cylinder, and dense honeycomb holes in the longitudinal direction (there are also other shapes, such as spherical, polyhedral, reticulated partitions, etc. ), and a very thin platinum-rhodium-palladium active catalytic layer is sprayed on its surface as a purifying agent (also called catalyst).

Second, the working principle

When the engine exhaust gas is discharged through the exhaust pipe, due to the catalytic action of the purifying agent in the three-way catalytic converter, the activities of CO2, HC and nitrogen oxides are enhanced, so that an oxidation-reduction reaction occurs, wherein C0 is oxidized to colorless and nontoxic CO2 at high temperature, HC is oxidized to H2O and CO2 at high temperature, and nitrogen oxides are reduced to N2 (nitrogen) and O2 (oxygen), thus purifying the engine exhaust gas.

Third, the performance of "three-way catalytic converter" blocking fault

1, the first stage is slightly blocked. At this stage, the chemical compound is adsorbed on the catalyst surface. It only shows that the purification function of tail gas is reduced. Exhaust emissions exceed the standard.

2. The second stage is a moderate plugging stage: chemical compounds have accumulated on the catalyst surface to a certain extent, and the exhaust back pressure increases at this stage. Fuel consumption increases and power decreases.

3. The third stage is a serious congestion stage. Due to the serious blockage, the working temperature of the "three-way catalyst" rises. A high-temperature sintering plug is formed at the front end of the three-way catalyst.

4, high temperature sintering blockage. There are two kinds of high temperature sintering blockage: one is metal sintering blockage. One is coking blockage caused by carbon deposition sintering. It depends on whether antiknock agents containing lead and manganese are used in the fuel. At this stage, the power drops seriously, and the engine often shuts down. In severe cases, the exhaust pipe burns red and even the vehicle spontaneously ignites.

4. Method for detecting and judging blockage of three-way catalytic system:

Three-way catalytic converter is affected by its own harsh working environment and conversion performance characteristics, and various failures will also occur in the process of use. For example, the phenomenon of engine power drop, flameout or starting difficulty, and excessive exhaust gas caused by the blockage of three-way catalyst may interfere with our fault judgment.

1. Check whether the voltages of oxygen sensors before and after the three-way catalytic converter are consistent. If the two are consistent, it means that the three-way catalyst is damaged, that is, it is blocked or the three-way catalyst is burned due to engine fire.

Put your hand into the exhaust pipe and see if you can feel the airflow. If you can't feel it, it means it's blocked.

3. Remove the air filter. Step on the gas in place. Look at the time, the air filter emits black smoke.

4. Use the temperature difference before and after the temperature-sensitive three-way catalyst to judge whether it is blocked.

5. The maximum speed cannot be reached during the test run, and the acceleration is poor.

The reason of verb (verb's abbreviation) blocking

1, gasoline: gasoline with high sulfur content is easy to form chemical complexes in the three-way catalyst, causing blockage. Poor oil quality and more colloidal gasoline are easy to cause blockage of three-way catalytic converter. The use of leaded or manganese-containing gasoline as antiknock agent is easy to cause the blockage of three-way catalytic converter, although the use of leaded gasoline has been strictly prohibited in China. However, in some areas, the lead pollution of gasoline during transportation and storage is serious. In order to reduce costs, some small refineries are still illegally using lead-containing antiknock agents. Manganese-containing antiknock agent has been banned in developed countries, but it is still used in most parts of China. The use of ethanol gasoline is easy to cause the blockage of the three-way catalytic converter, and ethanol gasoline is easy to form carbon deposits in the combustion chamber. At the same time, ethanol gasoline can clean the colloidal carbon deposits in the intake system and combustion system, and the cleaned colloidal carbon deposits are easy to form blockage in the three-way catalyst.

2. Engine oil: Long-term use of engine oil containing sulfur and phosphorus antioxidants is likely to cause blockage of the three-way catalyst.

3. Road: Because the combustion products produced by cars under the conditions of acceleration and deceleration are the most incomplete. Therefore, driving on a congested road for a long time is likely to cause the blockage of the three-way catalyst.

4. "Disassembly-free cleaning and maintenance of oil nozzle and air inlet": a large amount of colloidal carbon deposits will be washed down during cleaning. Therefore, it is easy to cause the blockage of the three-way catalytic converter, which is also the reason why the fuel consumption of some vehicles increases after the "fuel nozzle and air inlet are cleaned and maintained without disassembly".

5. Turbocharging: Turbocharged vehicles are prone to three-way catalyst blockage. This is mainly caused by improper operation of the driver. The blockage of "three-way catalyst" is gradually formed and reversible. Blockage can be reduced by chemical processes such as oxidation and gasification, or by physical processes such as desorption and evaporation of volatile components and gaseous components.

Solutions to intransitive verbs

"Three-way catalytic converter" congestion is a very common problem, especially in cities with congested roads. This problem is also prominent in areas with poor fuel quality. The blockage of "three-way catalyst" not only seriously leads to the increase of vehicle fuel consumption, the decrease of power and the excessive exhaust gas, but also causes the exhaust pipe to burn red, leading to the spontaneous combustion of the vehicle. For a long time, there is no effective preventive measure for the blockage of "three-way catalytic converter" in garage. There is no effective treatment method for the blocked "three-way catalytic converter". Only replace it. The price of three-way catalytic converter depends on whether there is an exhaust pipe or not. Generally, the regular price of catalytic converters without exhaust pipes is 800- 1200 ex-factory price, but 4S shops will have to add money when they see it. If the regular 4S shop is around 2000+.