5 Reasons why fitting a cheap Catalytic Converter could Kill your car's Performance 

  Engine management is at the heart of the modern car. The car will only reach it's full potential if all components are functioning properly. Full potential means performance in terms of speed, acceleration and fuel economy.

Modern cars are increasingly under digital control. The central management controller is the ECU - the Engine Control Unit. This ECU receives

information from all the other components in the engine telling it what is happening so that it in turn can control the amount of fuel etc going into the engine. The catalytic converter is an important part of the system.
Not surprisingly the catalytic converter and exhaust system are important components because they maintain the back pressure in the system which has been built into the specifications of the vehicle and into the mapping of the ECU. There are 'Original Equipment Manufacture' (OEM) cats and there are after- market (Pattern) units. While many pattern parts are good they can fall below specification. Fit an aftermarket cat which falls below specification and the system will be unbalanced and not perform optimally.

Be sure to find out what has gone wrong with your catalytic converter before replacing it. Have it checked professionally by a mechanic using car diagnostic equipment.
Here are some of the reasons for failure:
Water has got in - driving through water

Oil, water or anti-freeze has entered from the engine - internal leak e.g. head gasket failure

Leaded petrol has been used unwittingly. Even small amounts will cause damage or failure because leaded fuel coats the ceramic honeycomb core and prevents it from interacting with the exhaust gases.

Engine is out of tune/ not set up to OEM spec.

The overall health of your vehicle will be revealed by diagnostic check of :

fuel injection duration

manifold pressure

spark strength

timing

emission levels

What does the catalytic converter do?

The catalytic converter works on the basis of a catalyst reaction. Inside the catalytic converter are precious metals fitted into a honeycomb structure. The exhaust gases flow through this and in the process harmful emissions are reduced or removed. Basically the catalytic converter is an exhaust box; exhaust gases flow through it; the chemicals inside change poisonous, toxic elements in the exhaust into less toxic substances.

Historically the invention of the catalytic converter was inspired by the smogs of Los Angeles. These famous smogs have been blamed on a number of things including the geography of the country and the exhaust gases from thousands of cars. The catayltic converter had to wait until the introduction of lead-free fuel because leaded petrol is no-go for catalytic converters ; it coats the metals inside and disables the converter making it useless very quickly.

In many countries and states it is illegal to run a vehicle without the catalytic converter fitted.

So is the catalytic converter the answer to pollution problems? One criticism of the 'cat' is that is only functions properly when it reaches effective working temperature. This can take up to 30 minutes - not much good on shorter journeys. To get around this pre-heaters are fitted so that optimal temperature is more quickly achieved.

Another criticism is that the catalytic converter removes harmful emissions but 'turns' these into carbon dioxide - well known as the main gas contributing to 'global warming'.

The precious metals used in production come mainly from Norilsk, in Russia. Their production has contributed to Norilsk's reputation as one of the planet's most polluted cities. (Time magazine)

There are two-way and three-way converters and different converters for petrol and diesel engines. For more technical information be sure to read the Wikipedia article.

© Andy Hewing