ITV exhaust emissions

WHEN it’s time for your car’s ITV, the most usual items to check would be wheels, tyres, brakes and bodywork damage, some of which we have already covered.

We often forget about our cars’ contaminating emissions. This is one of the fundamental aspects to passing an ITV, because it is the most-common cause of failure.

For diesel engines, the most important test, when checking the emissions, is the opacity of the exhaust gases. The opacity limit depends on when the car was first registered, because the laws have changed, significantly, in the past few years. We are going to clarify doubts you may have.

How are gases measured?

Gases are measured out of the tail, or exhaust pipe, at the rear of the car. In general, if you follow the manufacturer’s servicing  schedules, and always use good-quality fuel, perhaps you would be less likely to have a problem.

This test is performed by putting the engine at idle, then accelerating the car to a speed of disconnection. (To the point where the injection with acceleration is empty.) To avoid damaging the engine, the ideal temperature to check this is over  80ºC, with all external energy drains disconnected, such as lights, radio etc.

The reader is introduced into the exhaust pipe, which is capable of measuring the opacity level or maximum absorption co-efficiency, which is the smoke emitted from the exhaust.

The value of gases for cars registered after 1st July 2008 is 1.5 m/l. If your car is older, the limit is set at 2.5m/1, for non-turbo vehicles, and 3m/1 for those fitted with a turbo. For new vehicles with the new emission sticker ITV Euro 6 and Euro VI, this limit is lowered to 0.7m/1. Vehicles registered before 1st January 1980 are exempt.

In the opacity test, the maximum number of allowed readings is eight. This allows the exhaust to blow out any residual soot sitting in the exhaust, and then get a correct reading. If the result is high, the last three readings are used to calculate the final amount.

The ITV manual states that there are three requirements to check gases.

*The engine should be hot following the manufacturer’s specifications, if there were any

*Before beginning the test, the engine would be revved to between 2500 and 3000 rpm, for approximately one minute, so as to reach the desired temperature in the catalytic converter, or DPF.

*Hybrid vehicles would require the manual override to switch on the engine, in order for the test to be completed .

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Posted by on Apr 18 2019. Filed under Motoring. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

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