Catalyst – a small but very important part of modern vehicles.
Understanding Catalysts:
Fuel combustion in car engine cylinders produces harmful substances like CO, HC, and NOx. A catalytic converter transforms these into CO2, N2, and H2O.
Historical Catalyst Development:
Developed in the 1970s, catalytic converters gained widespread use with environmental standards like Euro 2. Now integral to every car, they’re crucial for production and road operation.
Catalyst Components and Mechanisms:
The catalytic substrate, coated with precious metals, facilitates chemical reactions, converting harmful gases into harmless by-products. Modern converters are three-way systems, purifying gases sequentially.
Catalytic Converter Layout and Efficiency:
Despite complicating engine layout, placing catalytic converters closer to the engine enhances purification efficiency. This proximity accelerates catalyst heating, crucial for reactions occurring above 300°C.
Common Catalyst Failures:
Catalytic converters usually last 60-90 thousand miles. Melting, ceramic breakdown, and clogging are common faults. Signs of failure include reduced power, starting issues, and unusual exhaust characteristics.
Signs of Catalytic Converter Issues:
Recognize potential issues through reduced engine power, starting problems, or increased fuel consumption. Unpleasant odors or a rumbling noise indicate immediate replacement is necessary.
Several factors can lead to malfunctions in the catalyst, and here are the main ones:
- Poor-Quality Fuel: Often, low-octane gasoline is a culprit. The Engine Control Unit (ECU) responds by retarding ignition timing, causing incomplete combustion in the exhaust and raising exhaust gas temperatures.
- Ignition Misfires: Unburned fuel can combust in the catalytic converter.
- Incorrect Air-Fuel Mixture: The same effect as ignition misfires, but caused by sensor or injector malfunctions.
- Mechanical Damage to the Converter: Ceramic substrates do not tolerate increased vibrations and impacts on the converter’s casing.
- Thermal Shocks: Rapid cooling of the catalytic converter with water from puddles or other water obstacles can cause cracks in its casing.
- Fuel Additives: Undesirable additives in gasoline can increase its combustion temperature.
- LPG (Propane) Gas: The combustion temperature and octane rating of gas are higher, causing partial combustion in the catalytic converter.
- Engine Design: Ironically, sometimes the design of engines may create conditions that contribute to the rapid deterioration of the catalytic converter. For example, new low-emission engine designs are programmed for quick warm-up. In cold conditions, the ECU enriches the mixture, leading to incomplete combustion in the converter.
To avoid problems with the catalytic converter, it is advisable to follow some simple recommendations:
- Avoid prolonged engine cranking with the starter to prevent fuel flooding.
- Do not start the engine by pushing the vehicle (bump-starting).
- Avoid checking cylinder operation by disabling ignition spark plugs.
Additionally, keep in mind that the catalytic converter heats up to very high temperatures during operation, posing a fire hazard. Therefore, refrain from parking on dry grass, wooden platforms, or similar locations.
REPAIR AND REPLACEMENT OPTIONS
The original catalyst is a rather expensive component due to the use of high-cost materials. Therefore, when it fails, some car owners consider alternative repair options, including removing the catalyst from the exhaust system. The most common alternatives are:
- Cell Knockout: The exhaust system is disassembled to gain access to the catalyst’s internals. Ceramic cells are then knocked out with a long metal object (such as a pry bar), and their remnants are removed. Drawbacks of this repair include check engine errors, which can be addressed by reprogramming the Engine Control Unit (ECU) or installing ‘cheaters’: mechanical devices that close off oxygen sensors or electronic devices that send ‘correct’ signals to the control unit. Additionally, the car’s environmental class inevitably drops, which may cause issues during emissions inspections. Cases of increased exhaust noise to an uncomfortable level and local overheating near the catalytic converter are not uncommon.
- Installation of Flame Arrester: The faulty catalytic converter is removed, and a component resembling another resonator is installed in its place. The flame arrester, also known as a ‘strainer,’ typically consists of a cylinder with a double-layered casing and a complex (often X-shaped) internal structure. Similar to the stock catalytic converter, the flame arrester reduces engine noise, slows down, and partially cools the exhaust gases but does not neutralize them. Therefore, installing a flame arrester entails the same ecological and electronic issues as in the previous case.
- Universal Catalytic Converter: Among all the methods to save on catalyst replacement, using a non-original part is the only one that does not cross ethical boundaries and is generally recommended. In this case, there is no need to interfere with the engine’s software, and problems with environmental standards are less likely to occur. The main drawback of aftermarket catalytic converters is their low lifespan, rarely reaching figures exceeding 38,000 to 50,000 miles compared to the original.
Summarize!
Replacing the catalytic converter, whether with an original part or alternative options, can be a complex task. Interfering with the car’s software without sufficient experience and qualifications is strongly discouraged. Therefore, in case of issues with the catalytic converter, as well as with other car systems, it’s advisable to consult professionals – for example, RepairPal. However, if you possess the necessary skills or have consulted with an auto mechanic and need a catalyst, you can always fill out the form on our service, myNextParts. Hundreds of sellers will see your request and offer their options. For more detailed information on how the parts search service works, you can familiarize yourself here.
If you are going on a long road read this article.
