Last Friday we talked about the Gas test in gasoline vehicles carried out in the ITV. Today, we are going to do the same with diesel vehicles.
In this case, it is called Opacity Test and it measures, as its name suggests, the opacity of the exhaust gases with the opacimeter. In other words, what is measured in this test is the carbon or black smoke that comes out of the exhaust.
If when hitting a strong acceleration, our car emits black smoke, it may not pass the opacity test. One recommendation is that, when we are on our way to the ITV, it is to give the engine a little joy and squeeze a couple of gears to the red zone. With this we will be able to do a cleaning that will come in handy for the test they carry out on the ITV.
What is the ITV gas test?
La gas test of the Technical Inspection of Vehicles (ITV) is a procedure carried out during the mandatory periodic inspection to evaluate the exhaust emissions of vehicles. The objective of this test is to verify that the gases emitted by the exhaust comply with the limits established by current regulations for environmental protection and pollution control.
During the ITV gas test, a gas analyzer is used to measure and analyze the concentrations of different gases present in the vehicle exhaust fumessuch as carbon dioxide (CO2), carbon monoxide (CO), unburned hydrocarbons (HC) and oxides of nitrogen (NOx).
The vehicle is placed on a special test bench where the exhaust pipe is connected to the gas analyzer. Measurements are made under different conditions of acceleration and revs to simulate different driving situations. Based on the results obtained, it is evaluated whether the vehicle's emissions comply with the limits established by the corresponding regulations.
In case the values of emissions exceed the permitted limits, the vehicle will not pass the ITV gas test and it will be necessary to carry out the corresponding repairs or adjustments to reduce emissions and meet the required standards before undergoing the inspection again.
The ITV gas test is essential to ensure that vehicles comply with environmental requirements and contribute to the reduction of air pollution.
Diesel exhaust gases
The gases emitted by a diesel engine contain a combination of various components, including:
- Carbon dioxide (CO2): It is the main component of the exhaust gases of a diesel engine. CO2 is a greenhouse gas and contributes to global warming.
- carbon monoxide (CO): It is a colorless and odorless gas that is produced during the incomplete combustion of fuel. CO is toxic and can be dangerous in high concentrations.
- Nitrogen oxides (NOx): Nitrogen oxides, which include nitrous oxide (NO) and nitrogen dioxide (NO2), are formed during combustion at high temperatures. They are polluting gases that contribute to the formation of smog and can cause respiratory and environmental problems.
- Unburned hydrocarbons (HC): Unburned hydrocarbons are volatile organic compounds (VOCs) that have not been completely burned during combustion. These compounds can contribute to smog formation and have negative effects on air quality.
- Solid particles: Diesel engines also emit fine solid particles, known as particulate matter or soot. These particles are harmful to human health and can cause respiratory problems, especially in high concentrations.
Gas test procedure for diesel vehicle
The procedure for performing this test differs a bit from the one explained for gasoline cars. First of all, it is important that the engine temperature is close to 80º C. Before carrying out the test, the inspector must measure the oil level to check if it is correct, if it is not between the minimum and maximum, the test cannot be performed.
The test, as a general rule, It must be carried out by the ITV inspector and it consists of fully accelerating the car, in automatic vehicles it will accelerate a little less, about 2/3 of the total. The acceleration will normally be repeated several times to obtain a reliable result.
The maximum values for this test, for vehicles registered before the July 1th,2008, is 3,0 m-1 for cars with turbo and 2,5 m-1 for those without. For all vehicles registered after that date, the maximum value allowed is 1,5 m-1.
In case of exceeding the values that we have just mentioned, the vehicle will be rejected and must pass the ITV again. Among others, a possible cause may be that we have a dirty air filter. As we said before, simply revving up the car a bit and squeezing a couple of gears is usually enough to pass the test.
More information – How often do I have to pass the MOT?
Hello, I want to ask you what types of measurements should be applied to a vehicle that uses gasoline and one that uses diesel, both are measured for opacity? Thank you.