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Three in one - or how to save the catalyst

Replacing the failed catalyst will be costly, so it would be good to know in advance what the problems are with him, how things are with them in the aftermarket.

Until recently, we only knew of the catalyst as follows: it is the sort of thing that is not clear why it is not clear how it works that our gasoline it "kills" in general - nothing but trouble. Cut - and no problems! But gradually we began to get used to the fact that the catalyst - a thing after all It's a useful, at least thought about "surgical intervention" in the exhaust system is visited by fewer and fewer and fewer goals.

In the spring, when the traffic police are beginning to "fight for the purity of the air," dumped on us one more problem - the need to adjust the SB. Owners of cars equipped with catalytic converters, do not even think, and check posts without passing SB tremble at the knees and fear for your wallet. However, the same purse may well "lose weight" for a different reason. Fines for exceeding the levels of CO may seem penny compared to the cost of the purchase and replacement of the catalyst, if it fails. So it should not hurt to know how to handle it, and to do this you must first understand how it works and how to Ustron.

How do they work?

During the combustion of the mixture formed a number of working any harmful combustion products such as carbon monoxide (CO), various hydrocarbons (CH) and nitrogen oxides (NO). Although these substances are only 1% of the total exhaust (else - is nitrogen, carbon dioxide and water vapor), they are very harmful and require neutralization. There are several ways of dealing with harmful emissions - such as lean condition in which the engine is running or recirculated exhaust - but none of them compares to the effectiveness of the catalytic converter.

As experts say, the catalytic converter - a simple device in which there is a complex chemical process. "Inside the stainless steel body is a ceramic or metallic" brick "having a honeycomb structure. This monolith huge surface area, and the whole is covered with a thin layer of a special alloy - actually a catalyst containing platinum, rhodium and palladium. These precious metals are responsible for miraculous properties of the catalyst, they also define its high cost. "

Exhaust "wash" the surface of the monolith, and when the temperature reached the "critical" value of 270 ?� C, the catalytic reaction begins. Carbon monoxide is converted dioxide (carbon dioxide), hydrocarbons are converted into water and carbon dioxide again, and nitrogen oxides are converted to nitrogen and water. All this environmentally less harmful.

Catalytic converters can fairly effectively reduce exhaust emissions, and they do not affect the consumption of fuel and engine power. In the presence of a catalyst increases slightly exhaust back pressure, causing the engine loses 2-3 hp, but it is practically all the "board" for cleaning exhaust. However, the installation of the catalyst - not a perfect solution. Theoretically, it should serve as an infinitely as the above precious metals are only catalyst which is a chemical reaction, as is known, is not consumed. In practice, the catalyst life has its limits ...

What kills them?

The refusal of the catalytic converter can occur for several reasons, though, this is usually a gradual process, catch which is impossible without special equipment.

"Core" Most catalysts are made of ceramic - a material known for its fragility. The car can speed to get into a pothole, hit about something or even just a "strike" the catalyst body on the stone, and this catalyst "bricks" may crack. After this loss, "core" of their working qualities - time business.

Converters of new generation, comprising a metallic monolith, less vulnerable in this respect. Beat them, of course, possible, but in any case, is not so simple.

Enemies catalyst

In addition to physical destruction, there is another common cause of failure of catalyst. Fuel. It is extremely sensitive to the composition of the fuel. If leaded petrol, the tetraethyl lead, contained therein, is deposited on the active surface of the catalyst "bricks" and quickly "salted" it, causing all sorts of reactions cease. Already, it seems, at the pump and the hose began to put different size, color, and dispensers in different colors, and write about it on every street corner, and consumers are still sometimes confused and do not pour the gasoline. But it is enough to "burn" polbaka such gasoline, and the catalyst will be lost irretrievably.

Not only leaded gasoline - the enemy of the catalyst. The catalyst can be ruined and unleaded if faulty engine control system, incompletely combusted mixture or badly worn engine.

Ternary catalytic converters ("triple", because the catalyst is a combination of three precious metals) is installed only on those machines, engines which are equipped with closed-loop emission control. Before the catalyst is installed oxygen sensor that monitors the composition of the exhaust and transfers these data to a central processor. Depending on the oxygen content in the exhaust, the ECU regulates the composition of the combustible mixture and the ignition so as to maintain their optimum values. This serves as a protection for the main catalyst and also provides fuel efficiency and engine performance. The catalyst does not tolerate large variations in the working mixture. Poorly tuned engine with high content of hydrocarbons in the exhaust simply ruin the catalyst. If the mixture is too lean, it can cause overheating of the catalyst sharp, then again suffer from the monolith, only to have "physically". Thus, the "life" of the catalyst depends on the serviceability of the engine management system.

Much depends on the serviceability of the oxygen sensor. With the "age" becomes "lazy" or completely out of order, which affects the composition of the mixture and, consequently, on the health of the catalyst.

Spoil the catalyst can and badly worn engine exhaust, burning oil. This, together with the exhaust entering the catalyst in the "baked" onto the surface of the monolith, like varnish, and does not operate the catalyst.

There are other factors. For example - candles. Improper spark will not give complete combustion, which can cause disastrous in the catalyst reaction melt. "

Be very careful in the use of additives to fuel or oil. Most thought about it, and after all additives can also adversely affect the catalyst. If a product is not written, "is compatible with the catalyst," better not to take chances.

Another dangerous case - start the engine by towing. This may involve entering the catalyst just pure gasoline. This is, firstly, catalyst poisons, but can also cause an instant reaction and even explosion. See also where you are going - try not to fall into deep puddles. The operating temperature of the catalyst is about 900 ?� C. The sudden hit it in the water can be fatal.

In general, it is seen that the lifetime of the catalyst depends upon the conditions of use. Most catalysts suffer on machines operating in urban conditions when the engine is part of the plant. On the other hand, during prolonged high-speed driving on highways catalyst also spoils what is overheating.

Finally, you would be wise, if you become regularly inspect the entire exhaust system. If the brackets are broken or loose rubber suspension, exhaust pipe will vibrate, transferring the catalyst to unnecessary stress.