| Choosing the right catalytic converter for your | | | | cause a catalytic converter to overheat. Problems |
| car is increasingly recognised as one of the most | | | | such as improper float or air/fuel mix |
| important decisions you will make when | | | | adjustments and worn metering rods can damage |
| maintaining your car. Whether you are looking to | | | | the catalytic converter. The choke system also |
| maximise performance, minimise fuel consumption | | | | needs to be operating properly so the right level |
| or do your bit for the environment getting the | | | | of fuel enters the system. If too much fuel |
| right catalytic converter for you will save time, | | | | enters the system it will overheat and eventually |
| money and avoid the headaches of failing an | | | | fail.Canister Purge Valve Control - This vacuum |
| MoT.Here are some frequently asked questions | | | | operated valve vents fuel vapour from the |
| about catalytic converters:Why should I have a | | | | carburettor bowl to the charcoal canister. If the |
| catalytic converter?If your car was fitted after | | | | vacuum is breached the charcoal canister will |
| 1st August 1992 with a catalytic converter from | | | | flood, causing the air/fuel mixture to become |
| new, you need to have one for the MoT. It | | | | very rich. This will cause the catalytic converter |
| needs to be in good working order to comply | | | | to overheat and break down.Noisy |
| with the Government's emissions legislation. The | | | | A catalytic converter should not be considered to |
| engine has been designed to work with a Cat and | | | | be a silencer although it does have some silencing |
| besides giving out toxic emissions, the | | | | qualities. Noise can be caused by excessive fuel |
| performance will be reduced if your Cat is not | | | | getting into the catalytic converter.What happens |
| working properly. You will fail the annual MoT if | | | | if my Cat fails? If a catalyst fails it can block and |
| either it is not present or it is not in good working | | | | the car will break down.What does my Cat do? |
| order.Can I remove my Cat? If your car was | | | | Catalytic converters are specialist environmentally |
| registered after 1st August 1992 you must have | | | | friendly devices fitted in the exhausts of vehicles |
| the Cat present and working for the MoT. | | | | which ensure that hydrocarbons are burnt off and |
| Previously registered cars can have the Cat | | | | that minimise the emission of harmful pollutants. |
| permanently removed.Why do people want to | | | | Cars fitted with converters can use only unleaded |
| remove their Cats? Without a Cat the engine | | | | petrol as the lead in leaded fuel poisons the |
| gives more power and reduced petrol | | | | converter and irreparably damages it.Car |
| consumption. You may remove the Cat for track | | | | manufacturers have ruled out the retrofitting of |
| / competition / display use, for example.Why | | | | catalytic converters on older cars, saying that it |
| might my Cat fail? Road Damage | | | | could irreparably damage the converter, as |
| The outside of the cat can be damaged by | | | | vehicles which have been using leaded fuel for |
| hitting solid objects in the road. ie, speed bumps, | | | | many years have lead deposits in their engines. |
| large rocks etc.Plugged or contaminated | | | | On fitting with a catalytic converter, these |
| Plugged or contaminated catalytic converters are | | | | deposits could poison the Cat and damage it |
| caused by the wrong sort of fuel in your car. | | | | permanently.Unleaded fuel, when burnt, produces |
| Using leaded or lead replacement fuel will plug up | | | | gases such as carbon dioxide, carbon monoxide, |
| the monolith and cause it to stop working. A | | | | hydrocarbons, and oxides of nitrogen, the latter |
| similar thing will happen if fuel additives are used | | | | three can be poisonous or carcinogenic. A |
| that are not suitable for use with a catalytic | | | | Catalytic Converter, which is working correctly, |
| converter.Melted / Broken substrate | | | | creates a chemical reaction between these gases, |
| A monolith is usually broken when it is impacted | | | | which converts them to relatively harmless gases. |
| by an object or when it suffers a sudden change | | | | It is critical for the environment that you have |
| in temperature. If the catalytic converter suffers | | | | your Catalytic converter checked regularly to |
| road damage (See section on road damage) the | | | | ensure it is functioning properly.Catalytic |
| monolith inside can be cracked due to it being | | | | converters fitted to vehicles can reduce toxic |
| crushed by the movement on the steel can.The | | | | emissions (e.g. Carbon Monoxide, NO2, HC) by up |
| use of exhaust paste before the catalytic | | | | to 90%. Catalytic converters do not reduce CO2 |
| converter can cause the monolith to break. When | | | | emissions.Can I fit a Cat to a car which doesn't |
| the exhaust paste has hardened, small pellets | | | | have one? If your engine ran on leaded petrol you |
| may break away and shoot into the catalytic | | | | cannot. The old deposits will poison the Cat.How |
| converter. The monolith will gradually be | | | | can I best care for my Cat? There are several |
| destroyed by these pellets and break down. The | | | | things you can do to ensure your 'cat' has a long |
| catalytic converter can also be damaged by | | | | and healthy life.When fitting the catalytic |
| excessive engine vibration. Another possible cause | | | | converter, don't use exhaust paste in front of the |
| of a fractured monolith is a sudden temperature | | | | cat. When the exhaust paste hardens it can break |
| change. (See number 7 in "Caring for your | | | | off in chunks and damage the monolith. Paste can |
| Catalytic Converter")The monolith can be melted | | | | also block the monolith.Always use the correct |
| when unburned fuel is injected into the catalytic | | | | fuel for your car.Never use a fuel additive without |
| converter. This can be caused by the car being | | | | first reading the instructions to find out if it is |
| bump or tow started, or if the car's engine | | | | suitable for use with a catalytic converter. If in |
| requires several turns before firing. More | | | | doubt, contact the manufacturer of the |
| information can be found on this is the section on | | | | additive.Never attempt to bump or tow start |
| "Overheating".Overheating | | | | your car. This causes unburned fuel to be injected |
| There are many problems that can cause a | | | | into the catalytic converter, which makes the |
| catalytic converter to overheat or fail. The most | | | | monolith overheat and melt.Never tow anything |
| common cause is unburned fuel entering the | | | | that is too heavy for your vehicle to cope with. |
| catalytic converter. Also faulty spark plugs and | | | | For example, an overloaded caravan will actually |
| leads will cause the engine to misfire and ruin the | | | | push a car along when it travels downhill. This |
| catalytic converter. It will also be damaged if the | | | | sends unburned fuel into the exhaust system and |
| distributor timing is out.Oxygen Sensor - An | | | | can cause the monolith to melt down.Have your |
| oxygen sensor collects and sends information to | | | | car regularly serviced to your car makers |
| the Electronic Control Unit. This is used to control | | | | specifications. In particular, make sure the engine |
| the fuel/air mix. If the oxygen sensor is faulty, or | | | | is running properly. A poorly tuned engine can |
| it has been contaminated with silicone from | | | | cause the monolith to break down or become |
| anti-freeze or sealant, he fuel/air mixture will not | | | | covered in soot, which stops it working |
| be corrected and excess fuel will enter the | | | | regularly.Take care when driving through deep |
| catalytic converter, causing it to overheat.Fuel | | | | puddles, fords or parking when there has been |
| injection systems - If a fuel injector is leaking | | | | heavy snowfall. The catalytic converter operates |
| internally or dribbling fuel into the engine the | | | | at an extremely high temperature, and when it |
| catalytic converter may be damaged. The excess | | | | comes into direct contact with water or snow it |
| fuel will enter the exhaust system and cause it to | | | | cools down more rapidly than the monolith, and in |
| overheat. Due to the varying fuel injector | | | | extreme circumstances the monolith can be |
| systems the proper manual should always be | | | | crushed as the steel shell contracts.Don't park |
| consulted when trying to diagnose a problem.Map | | | | your car over long grass or anything similar. As |
| Sensors - Map sensors tell the Electronic Control | | | | the catalytic converter operates at such a high |
| Unit the load on the engine and the amount of air | | | | temperature it can actually set the grass on |
| entering it. If this sensor fails it causes a rich | | | | fire!Drive slowly over speed bumps or very |
| condition in the engine, which can overheat the | | | | bumpy roads to reduce the chance of the |
| catalytic converter causing it to fail.Carburettor | | | | exhaust system being grounded. This could cause |
| systems - A worn or defective carburettor can | | | | impact damage to the catalytic converters. |