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  The Invisible Killer from Your Engine  
- Tuesday, September 18, 2001  By Chips  Bookmark and Share

A reminder of the danger of carbon monoxide......

[+ click to enlarge]
Early Kancils don't have catalytic converter
Early Kancils don't have catalytic converter
Kembara is fitted with catalytic converter
Kembara is fitted with catalytic converter

The recent tragedy involving a mother and her children being gassed to death inside a car serves as a reminder of the danger of carbon monoxide (CO) poisoning and highlights the reason for the existence of catalytic converters in today’s cars. CO, a gas produced during combustion, is a colourless, odourless gas which limits the blood's ability to transport oxygen to body tissues. This places a strain on people with weak hearts and respiratory diseases, causing dizziness, headaches, impaired coordination; at very high levels, death is likely.

In the tragedy, the car’s occupants had remained inside with the engine idling and the air-conditioner running for hours and it is believed that CO fumes from the exhaust had somehow accumulated in the cabin and killed them. How the fumes got into the cabin is the subject of investigation by authorities as well as Perodua, which has assistance from its technical partner, Daihatsu.

While a catalytic converter is supposed to minimise the presence of CO, such a device was not present in the Kancil because early models of the Kancil are not required to have it (the Kancil EZ automatic is, however, fitted with the device). The law making catalytic converters in petrol-engined cars mandatory was only introduced in recent years and models which were introduced earlier than the implementation date have been exempt (even if they are still being assembled). Other Perodua models such as the Kembara, Kenari and Kelisa have catalytic converters as standard.

But even then, it is abnormal for exhaust gases to seep into the cabin, let alone accumulate to lethal levels. The cabin is generally sealed from outside air if the windows are closed and the ventilation system is set to recirculate internal air. It is, however, possible for gases from the exhaust system to seep in if some modification was made to the vehicle, an area investigators are looking into. A damaged exhaust system allowing exhaust gases to escape upwards into the cabin is also a possibility. Exhaust gases can also enter through the rear of the car while it is moving. If the rear hatch is open, the turbulence behind the vehicle can blow exhaust gases into the cabin.

It is not known where the car was parked but Owner’s Manuals in many cars do warn of the dangers of running the car inside an enclosed space (although closed garages are not so common in this country). Such a situation allows the build-up of exhaust gases to dangerous levels and be life-threatening to people inside the garage as well as occupants in the vehicle.

In the case of the Kancil, it is possible that the exhaust gases built up inside the cabin because the ventilation system was set to recirculate air rather than draw in fresh air from outside. If the car had been parked in an open space, perhaps the intake of outside air would have diluted the polluted air inside the cabin, averting the tragedy. However, most people don’t do this because it reduces cooling inside as outside air is warmer (and outside smells get in). Now that such a danger is evident, perhaps it is wise to do so if you are waiting in an idling car or better still, wind down the windows slightly. Ideally, the engine should be switched off when the car is parked but understandably, many people desire the comfort of the air-conditioner, especially in our climatic conditions.

On newer cars which have catalytic converters, the danger of CO poisoning is lower as the catalytic converter eliminates 99% of the toxic elements through chemical conversion. This device, which has been around since the 1970s, was initially a ‘bolt-on’ item and affected performance. However, after a few years, engineers tuned engines to allow for the presence of the catalytic converter and its effect on back-pressure and performance levels were no longer an issue. Nevertheless, there are still some people who deliberately remove the device to improve their engine’s performance, an action which is illegal in some countries. In fact, with emission control devices being integral with the engine management systems, tampering with the device will likely cause a reduction of performance and worsen fuel consumption as the system attempts to compensate and usually enriches the mixture excessively.

Catalytic converters are designed to last for many years and at least 300,000 kms. However, they can be damaged by lead which is why unleaded petrol is a must. The lead covers the catalyst and prevents the chemical reaction from taking place. This is why, before catalytic converters could become mandatory in Malaysia, unleaded petrol had to become widely available.

There is no specific maintenance needed for the catalytic converter but if you are concerned about air pollution, then it is useful to have the exhaust gases analysed periodically. The bigger workshops have machines to do this as it is also a way to assess the state of the engine tune.

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