Every year, more and more demands are placed on vehicles equipped with an internal combustion engine in terms of exhaust cleanliness. Sometimes high environmental standards make it impossible to register a car in a particular country.
The modern exhaust system is equipped with a special element that plays an important role in the purification of the exhaust. Thanks to this, the manufacturer does not need to abandon the use of a standard line of power units for the next car models. What is the peculiarity of this part, and what can be done if it is out of order?
What is a catalyst
Let's discuss terminology first. The catalyst is an integral part of the combustion products removal system for a mixture of hydrocarbon fuel and air. The device works on the basis of a chemical process of neutralizing harmful gases and heavy particles. Thanks to this, the exhaust fumes from these vehicles do not increase the level of smog in the city.
You can find this part in the exhaust line. It is placed as close as possible to the exhaust manifold. The reason for this is that the reaction does not occur at low temperatures. Since the gases at the exit from the engine have a maximum temperature index, the device functions with greater efficiency.
Why it is needed
In recent years, the number of cars on the roads of most countries has increased. The most affordable variant of vehicles has an internal combustion engine as a power plant. Although there are environmentally friendly (at least clean during operation) vehicles such as electric vehicles or hydrogen fuel cell cars, they are not yet available to most motorists.
Naturally, each state is interested in maintaining a clean environment, since not only their existence depends on this, but also the frequency of occurrence of cataclysms on the planet. The catalyst ensures the neutralization of hydrocarbon compounds, nitrogen oxide and other substances.
Automotive catalyst device
The catalytic converter is manufactured in the form of a metal flask. It is installed immediately after the intake pipe. If you cut the flask, you can see a ceramic insert with a cellular structure inside. The cells are like honeycombs in a bee hive. This shape (hexagon) allows you to distribute as evenly as possible a large number of partitions with which the gas coming from the engine will contact.
Ceramic (sometimes made of metal) fins are alloyed with precious metals such as gold, platinum and iridium. The presence of these alloys is due to the fact that they enter into a chemical reaction with hot gases that are part of the ICE exhaust. The process is accelerated depending on the degree of heating of the catalyst fins. The hotter they are, the more efficiently the conversion of hydrocarbon and nitrogenous compounds into carbon dioxide and nitrogen will be.
In order for the catalytic converter to perform its function properly, an oxygen sensor is installed in the exhaust system. About how this element works separate review.
Catalyst malfunctions and their causes
In a car, the catalyst can be in working, semi working and non-working condition. Naturally, the driver will be able to determine the state of the catalyst if he is attentive to the behavior of his vehicle. Here are some indications of catalyst problems:
- Decrease in the efficiency of the power unit. If the engine slowed down decently in power, the car began to gain speed poorly and, in general, the dynamic characteristics decreased markedly, it is worth showing the "patient" to a specialist. True, these symptoms can also be harbingers of malfunctions in other vehicle systems. In the event of a critical breakdown of the neutralizer (the honeycombs are melted and clogged, too much plaque has formed on them), the motor will start poorly and often stall. This is due to the fact that a decent resistance is created in the exhaust manifold, which prevents high-quality ventilation of the cylinders and the filling of a new portion of BTC.
- The car began to consume much more fuel. The problem is the same, only the control unit tries to correct the situation, and supplies a richer mixture to stabilize the crankshaft speed.
- Loud noise coming from the exhaust system. Do not confuse this rumble with a burned-out silencer. This is a sign that the process of destruction of active elements has begun inside the catalyst. The pieces that have fallen off begin to quickly move along the body of the can, since they cannot be removed with the exhaust, therefore, they hit the catalyst walls with force. This can be heard especially clearly during a cold start and at high engine speeds.
- Check lit up with motor indication. Of course, this is a universal signal. It may indicate other malfunctions. In this case, diagnostics should be carried out, which will reveal the error code - from which node the signal came. So, the ECU can initiate an error notification when it receives incorrect data from the lambda probe.
Typically, a catalyst will last for a very long time. With proper operation and timely maintenance, its working resource is almost identical to the "life" of the entire vehicle. This parameter is set by the manufacturer - the technical documentation indicates the service life of the vehicle. However, situations are not uncommon when a catalyst can work out its resource much faster.
The catalyst never fails suddenly. Rather, this is a consequence of some mistakes of the car owner himself. It is mainly associated with malfunctions in the fuel supply or ignition system. A certain amount of unburned fuel enters the exhaust system, which remains in the form of carbon deposits on the edges of the device. When the fuel is burned out in the catalyst, its elements heat up more strongly and are destroyed. Sometimes this happens due to wear of the valve stem seals, and engine oil enters the exhaust manifold along with the exhaust.
To prevent this from happening, you need to periodically check the ignition system, perform computer diagnostics to eliminate errors in the engine settings (poor-quality fuel combustion). Also, do not save on fuel. If a gas station is not famous for its quality products, you should not refuel it.
Automotive Catalyst Diagnostics
To check if the catalyst is not clogged, you can carry out one simple procedure. We start the engine, put our palm to the tip of the exhaust pipe. During normal operation of the neutralizer, a slight pulsation will be felt (even with a well-executed exhaust system, an uneven movement of gases will be observed). If gases exit the pipe in an even flow and without pressure, this is a clear sign that the part is clogged.
During such a diagnosis, you can ask the assistant to turn off the engine, and at the same time keep your hand at the exhaust. If, even after turning off the engine, smoke continues to leave the pipe to a small extent, this further proves that the catalyst is clogged. An overpressure is created in the circuit between it and the motor, which squeezes out the gases, even when the internal combustion engine is shut off.
Replacing the catalyst
When a catalyst malfunction occurs, the service center specialists can offer three ways out of the situation:
- Remove the old element and install the original spare part to replace the broken one. This is the simplest option, but one of the most expensive. The fact is that in most cases, manufacturers select only a specific part that matches the parameters of the motor. Moreover, it is rarely when the automaker itself is engaged in the manufacture of spare parts. This is done by third party companies. The original spare part will be when the brand buys it and sticks a tag that it is the property of the brand. If the car owner chooses this option, then he will receive a 100 percent corresponding part, for which the manufacturer has adapted the operation of the unit.
- Install a universal modification. This option will cost less money. This is a kind of golden mean between price and quality. If a motorist decides to replace a part with a new one, this option is often chosen.
- Install the flame arrester. In this case, a "blende" is installed, which does not allow the control unit to recognize the absence of a catalyst. But the disadvantage of this procedure is changes in the operation of the motor, since the electronics will adjust its operation taking into account the resistance from the neutralizer. It will also affect the cleanliness of the exhaust.
The high cost of the element is due to the presence of precious metals in its device. The high cost of the part is one of the main reasons why many car owners with a damaged catalyst decide to simply remove it. If you just cut it out and put a piece of pipe instead of it, the least that can happen is that the motor will constantly work in emergency mode. In more modern cars, the ECU recognizes this problem and will not give the opportunity to start the car.
For this reason, before performing the procedure yourself, you should consult a specialist. Here's how to properly remove the catalyst:
- Diagnostics is carried out, and parameters are measured, which are recorded by the ECU with a working converter (indicators of lambda probes, fuel system, ignition, etc.);
- A diagram is drawn up of the proper operation of the motor with a working converter;
- The contact group going from the catalyst to the control unit is disconnected. The diagnosis is repeated;
- Instead of a catalyst, you need to put an imitator in the system, since you need to create something of the resistance that it creates;
- It is chosen what will stand instead of this element: just a pipe insert or an additional resonator;
- "Bogus", other sensors are installed, or the ECU is reflashed.
Installing the catalyst
Sometimes it costs almost as much to install deceptive elements, flashing and tweak the software as buying a new catalyst. In addition, if the car is still under warranty (of course, it is difficult to imagine what needs to be done with it to make the catalyst fly so quickly in it), then removing the part is automatic removal from the service period.
Another argument in favor of installing a new element is the mandatory inspection when crossing the border with some European states. If the part is removed and the electronics are correctly adjusted, the sensor, which is brought up to the exhaust pipe by a technician, will show real readings.
So, do not ignore the first signs of failure of the catalytic converter. And in order to extend its working life as much as possible, you cannot neglect elementary service procedures, even if they seem expensive.
Here's another short video on why you shouldn't cut out the catalyst: