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.Installation and disassembly of three-way catalytic converter (integral type)

2018-04-20

1.Installation and disassembly of three-way catalytic converter (integral type):
(1) Jack up the car safely.
(2) After cooling the three-way catalytic converter, unscrew the four  bolts and nuts that connect the exhaust pipe to the three-way catalytic  converter.
(3) Remove the three-way catalytic converter and gasket.
(4) Replace the two new gaskets and place them on the front and rear exhaust pipes.
(5) Install a three-way catalytic converter and tighten the bolts and nuts with a tightening torque of 43 Nm.

2. Disassembly and assembly of preheated three-way catalytic converter (integral type):
(1) Disconnect the battery negative cable. Note that the disassembly must be performed after the ignition switch  is switched to K position and the negative battery cable is disconnected  for 90 seconds.
(2) Remove the front exhaust pipe:
1 Loosen the two bolts and disassemble the bracket.
2 Remove the 2 fastening bolts and 2 fastening nuts of the front exhaust pipe and the middle exhaust pipe.
3 Using a 14mm socket wrench, remove the three fastening nuts from the  front exhaust pipe and the preheated three-way catalytic converter.
4 Remove the front exhaust pipe and gasket.

3. Remove the preheated three-way catalytic converter:
1 Check whether the preheated three-way catalytic converter is cooled.
2 Disconnect the oxygen sensor connector.
3 Remove bolts, nuts, and No. 1 exhaust manifold bracket.
4 Remove the bolts, nuts, and exhaust manifold bracket.
5 Remove 3 bolts, 2 nuts, preheated three-way catalytic converter, gasket, retainer and gasket.
6 Remove five bolts and two heat shields from the preheated three-way catalytic converter.

4. Reinstall the preheated three-way catalytic converter:
1 Install two heat shields on the new preheated three-way catalytic converter using 8 bolts.
2 Install new gaskets, retainers and gaskets on the preheated three-way catalytic converter.
3 Install the preheated three-way catalytic converter using 3 bolts and 2 new nuts with a tightening torque of 29 Nm.
4 Install the exhaust manifold bracket using bolts and nuts with a tightening torque of 42 Nm.
5 Install the No.1 exhaust manifold bracket using bolts and nuts with a tightening torque of 42N.m.
6 Connect the secondary oxygen sensor connector.

5. Reinstall the front exhaust pipe:
1 Replace the two new sealing gaskets on the left and right ends of the front exhaust pipe.
2Temporarily install 2 fastening bolts and 2 new fastening nuts for the front exhaust pipe and the middle exhaust pipe.
3 Use a 14m long socket wrench to tighten the front exhaust pipe and a  new fastening nut for the preheated three-way catalytic converter. The  tightening torque is 62N.m.
4 Tighten the two fastening bolts and the two fastening nuts of the  front exhaust pipe and the middle exhaust pipe. The tightening torque is  56N.m.
5 Use 2 bolt mounting brackets.

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Replacement notes
1. Must ensure that the engine is not a problem, not burning oil, burning oil, must overhaul the engine;
2. Clean spark plug carbon deposit or replace spark plug, clean  injector, air grid, throttle, oxygen sensor poisoning failure must  replace the oxygen sensor, then the measured data is accurate;
3. It is best to use 97# gasoline during the vehicle examination in  order to fully realize the effectiveness of the three-way catalytic  converter;
4.  Three-way catalytic converter light-off temperature of 230-300 degrees,  just put on a new three-way catalytic converter, need to heat the car  or run dozens of kilometers and then to the vehicle inspection,  inspection is best not to turn off the fire, avoid cold inspection Or, as soon as a vehicle is loaded, the effect of the vehicle  inspection is often inaccurate. At the same time, the owner is also  required to spend unnecessary expenses.
5. The OBD catalytic converter must be checked before and after the  failure of the light to detect poisoning failure, if it fails, it must  be replaced.

Cause of Issue

1. The temperature is too high.

(1)  The three-way catalytic converter at room temperature does not have the  catalytic ability, and the catalyst must be heated to a certain  temperature to have the ability to oxidize or reduce. Usually the  catalytic converter's light-off temperature is 250-350°C, and the normal  operating temperature is generally 400. -800°C.
(2)  The catalytic converter will produce a large amount of self-volume, the  higher the oxidation temperature, and when the temperature exceeds  1000°C, the catalyst of the inner coating will sinter and necrosis, and  it is also prone to spontaneous combustion of the vehicle. .
(3)  Therefore, it is necessary to pay attention to controlling various  factors that cause the temperature of the exhaust gas to rise, such as  too late ignition time or disordered firing order, or a broken fire.  This will cause the unburned gas mixture to enter the catalytic reactor  and cause the exhaust gas temperature to rise. High, affects the performance of the catalytic converter.

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2. Chronic poisoning.
(1)  The catalyst is very sensitive to elements such as sulfur, lead,  phosphorus, and zinc. Sulfur and lead come from gasoline. Phosphorus and  zinc come from lubricating oil. These four substances and their oxide  particles formed in the engine are easily adsorbed. On the surface of the catalyst, the catalyst cannot be brought into  contact with the exhaust gas, thus losing its catalytic effect, the  so-called "poisoning" phenomenon.

3. Surface carbon.
(1)  When the car is working at a low temperature for a long time, the  three-way catalytic converter cannot start, and the soot discharged from  the engine will adhere to the surface of the catalyst, resulting in  inability to contact with CO and HC. In the long term, the pores of the  carrier will be blocked, affecting Its conversion efficiency.


4. Exhaust gas deteriorates.
(1) Catalytic converters have certain limits on the conversion  capacity of pollutants. Therefore, the original exhaust gas must be  reduced to a minimum by in-vehicle purification technology.
(2) If the concentration and total amount of exhaust gas pollutant  components are too large, such as the mixture gas is rich, it will  affect the catalytic converter's catalytic conversion ability and reduce  its conversion efficiency.
(3)  In addition, since a large amount of HC and CO in the exhaust gas enter  the catalytic reactor, an excessive oxidation reaction occurs in the  exhaust gas. The large amount of heat generated in the oxidation  reaction will cause the catalytic reactor to be overheated and be  damaged.





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