AdBlue, what exactly is it?

AdBlue is a liquid solution used to reduce NOx (or nitrogen oxides) emissions from diesel engines. AdBlue is injected into the exhaust system between the engine and the SCR catalyst and converts the nitrogen oxides to nitrogen and water. As a result, you therefore have lower NOx emissions.

In this article, we take a closer look at what exactly AdBlue is.

What is AdBlue

As explained above, AdBlue is an aqueous solution added into the engine system. AdBlue is a mixture of demineralised water and pure urea

adblue dieselNot all passenger cars are equipped with one; your car must have an SCR system. SCR stands for 'Selective Catalytic Reduction' or Selective Catalytic Reduction. These are mainly Euro 6 diesel engines. From 2014, this system was introduced in trucks but from 2014 onwards also in several passenger cars. Several models of various brands use SCR catalyst such as Audi, BMW, Citroën, Ford, Mazda, Opel and Peugeot, for example.

How can I refill AdBlue?

Where you can refill AdBlue varies from car to car, sometimes the filler cap is next to the Diesel filler cap but sometimes it is under the bonnet. Not sure? Check your car's manual! It is often a blue screw cap with the text AdBlue on it.

You can refill AdBlue yourself, simply buy a jerry can of AdBlue and fill the reservoir. Just twist off the cap and pour. AdBlue is often available in 5- or 10-litre containers and available from various (online) shops. Buy AdBlue can easily be done at this webshop, for example.

When should I refill it?

If your car has an SCR system, there is probably a gauge in the car where you can see the level of AdBlue. Keep a close eye on the gauge and top up AdBlue as soon as the level gets too low.

If you have scheduled a service for your car, the mechanic in the workshop will often also check the level and top it up where necessary. If the AdBlue tank becomes empty, however, you should refill it yourself in time, make sure there is always enough fluid in the tank but don't overfill the tank. This is because if you pour too much of the fluid into the tank, it can overflow. You then have the chance that the liquid will crystallise, clogging the reservoir's filler neck. So stop filling the tank in time. If in doubt, we always recommend having it refilled by a specialist garage in your area.

Storage advice

Remember to store AdBlue at room temperature and in a dark place as the product can freeze at -11 degrees celcius and its composition can change due to exposure to UV light. So store it in a dark place and not too cold.

Nitrogen oxides?

Nitrogen oxides (NOx) are mainly released during combustion processes, where oxygen (O2) and nitrogen (N2) from the air react with each other. These combustion processes take place particularly in vehicles with diesel combustion engines. NOx is particularly harmful to the environment and is, for example, 40 times more toxic than carbon monoxide (CO) and 4 times more dangerous than nitrogen monoxide (NO).

By adding AdBlue, a chemical process occurs that reduces emissions of nitrogen oxides by up to 80% by converting much of it into nitrogen and water.

The famous 1.9 tdi of VW, Audi, Seat and Skoda

The well known 1.9 tdi engines of the VAG group have been used in many brands and models, from Audi to Skoda!

The first generation of this engine dates back to 1991, then known as the TDI-VP and was available as -75, 90 and 110 hp, and the fuel was delivered via a Bosch rotary pump. The strongest variant is characterised by the use of a variable geometry turbine and a floating flywheel (this is often replaced for a fixed flywheel when older). The engine was offered in a wide range of VAG models from 1991 to 2010 and quickly became popular for its low fuel consumption and good dynamics. But it was also criticised for being noisy. 

The technology behind TDI 

The direct fuel injection used in the 1.9 TDI engines requires very high precision and high pressure. In general, direct injection diesel engines are louder than indirect injection diesel engines, which is why a two-stage injector was introduced in the 1.9TDI engines. 

This solution allowed the implementation of the so-called pre-injection with traditional high-pressure "Bosch pump" fuel pumps that were mounted on 1.9 TDI engines from the beginning. The first smaller injection prepares the cylinder for the main injection of fuel into the cylinder and improves the main combustion, which is not sharp, i.e. it reduces the noise. The 1.9 TDI-VP uses a turbocharger, intercooler, EGR valve and heating elements in the cooling system for easy starting at low temperatures.

The new PD generation

In 1998, a new generation of 1.9 TDI - 1.9 TDI PD came on the market. This used pump nozzle injection, which replaced the traditional injectors and pumps. This solution helped to increase the injection pressure, thus reducing fuel consumption (in practice, the difference is nil) and again improving performance. Unfortunately, in this case a small side effect had already emerged: slightly higher maintenance costs, this engine had a floating flywheel and a turbine with variable geometry.

The noisy character of the TDI

The only accusation against the 1.9 TDI and 1.9 TDI PD is that they are quite noisy. Fortunately, this inconvenience is only felt in lower class cars, and generally at low speeds. When driving at a speed of around 100 km/hr, the noise isn't too bad, but the difference with, for example, a diesel of BMW is considerable. It is important to note that to counteract the vibrations, the manufacturer (VAG) uses engine mounts with oil-filled rubbers. 

The TDI was a breakthrough in the 90s 

In the late 1990s, Volkswagen brought a solution with the TDI that would later be used in many passenger cars. The pump-spray injection system made it possible to achieve even higher injection pressures, thus reducing fuel consumption. Unfortunately, neither the two-stage injector pump nor the pump-spray system eliminated the main disadvantages of the TDI engine: diesel rattling and strong vibrations transmitted to cars, pedals and steering wheels of smaller cars. If you hear a loud rattle under the bonnet of your car, it does not necessarily mean that there is something wrong with the engine - all 1.9 TDI engines do. 

The pump injector was an improvement

With the arrival of unit injectors, the 1.9 TDI engine began to run more quietly and the raw sound decreased somewhat. In addition, these engines had slightly lower emissions, which of course became increasingly important. 

In the case of the 1.9 TDI engine with a unit injector, it is especially important to check the timing belt replace them in time. Very high mechanical power is required to move the piston of the injection pump. That is why the timing belt is under extra strain.

Timing of TDI engines

With the 1.9 TDI engine, the intervals for changing the timing belt vary considerably and range from 60000 km to 120000 km. This depends on the engine generation. If you buy a car with a 1.9 TDI engine, it is best to replace the timing belt immediately when the last change is uncertain. 

Most reliable 1.9 tdi generation

The most reliable TDI generation are the earlier versions of the 1.9 TDI diesel, which has a rotary pump and outputs from 75 to 110 PS. The most popular version is the diesel engine with 90 hp. It is usually with fixed-geometry turbines, and with any luck, the car will no longer have a floating flywheel. A 90 hp 1.9 TDI engine can reach 500,000 km with regular maintenance, even if the driver has a heavy right foot.

Consumption of the 1.9 TDI engine

Of course, not unimportant for a diesel, the consumption! TDI engines can be very economical, especially the first generation with 75, 90 and 110 hp can easily achieve an average consumption of 1:18 and if you are a quiet driver, 1:20 is not at all exceptional. The new generation with pump injector is slightly more sensitive to the driving style of the driver. If you drive calmly, a consumption of 1:18 is also fine, but if you drive fast, it can suddenly become 1:15. Of course, still not bad values. Oil consumption is usually limited to 0.5 litres per 10,000 km, if your TDI uses more, it could indicate a leak or a space on one of the components.    

The 2.0 TDI vs. the 1.9 TDI

When the 2.0 TDI engine appeared in 2003, it was thought that the 1.9 TDI would slowly disappear from the VAG group's engine range. Unfortunately, the new diesel proved to be very unreliable. Partly because of this, the 1.9 TDI was still sold for over 6 years in various VAG models. So if you are faced with the choice of buying a 1.9 TDI or 2.0 TDI, choose the older generation of engines. These usually offer much more security and have a similar performance. 

CONCLUSION - 1.9 TDI engine

The 1.9 TDI engine comes in many models and versions, so you can easily find one that suits you. If the TDI has had regular oil changes, they are reliable, economical and quite fast workhorses.  

Of course, you may have bad luck once you buy a car with a 1.9 TDI engine. Fortunately, they are relatively simple blocks and low repair costs are the rule rather than the exception. 

EGR valve operation and problems

An EGR valve is found almost exclusively in diesel engines. This system was first tested by General Motors. This happened as early as 1970 and it has been a widely used technique ever since. The valve helps to reduce the emission of toxic substances from the atmosphere. Unfortunately, a dirty EGR valve can cause malfunctions. In this case, it can be cleaned or removed completely. After reading this article, you will know how an EGR valve works, how to maintain it and whether removing it is wise. 

Operation 

The term EGR valve stands for exhaust gas recirculation. General Motors first tested this system in 1970. It recirculates spent exhaust gases back into the air intake of an engine. This is also one of the reasons why the EGR valve can become contaminated. 

The system is controlled by the central computer of the car. Depending on the manufacturer, the valve is opened at a certain speed, for example 2000 rpm. 

The engine computer controls the EGR valve via a solenoid valve or an electric valve, depending on various parameters (water temperature, air temperature, engine load data, etc.).

By reusing the exhaust gases, the emissions (NOx) are reduced by 10 to 40%. This depends on the engine and the engine management. Each manufacturer has to comply with the emission regulations of the respective country, the engine management is adjusted accordingly.  

Disadvantage of an EGR valve

The engine emits an excess of nitrogen oxide and small particles into the atmosphere, which violates European emission standards. In an attempt to reduce such emissions, manufacturers install the EGR valve, which directs exhaust gas back to the injection so that it burns a second time. Unfortunately, this process creates excess hydrocarbons in the form of soot, which accumulates in the EGR system and sometimes clogs it up completely; this can affect the rest of the engine. The engine no longer functions as it should because of the unburnt gases that are injected into it. The EGR valve starts to malfunction when it is clogged; carbon emissions (soot) accumulate in the valve and restrict the mobility of the solenoid or the valve, which can lead to a complete blockage. The system fails and the engine computer switches to a lower operating mode, causing a significant loss of power.

A permanently open valve can damage your intake system. It is therefore important to regularly service the EGR valve of your diesel. Otherwise it can become a recurring problem. 

Symptoms of a defective EGR valve:

  • Power loss
  • Engine management light on (emission fault)
  • Black clouds of smoke when accelerating rapidly
  • A faltering car 

EGR valve removal

Although it is not permitted to remove or cap the EGR valve, in some cases it is the only way to get the car to function normally again. In extreme cases, you can also install a new valve, but this can be a costly affair. 

However, because it is not allowed, problems can arise during the MOT, the so-called soot measurement will show too high values, resulting in a car being rejected. Besides a complete replacement, cleaning can also work, although there is a chance that the problem will return in time. 
Finally, driving many short distances can also have a detrimental effect on the EGR valve, which is why, as with the soot filter It is wise to drive long distances at times.

Soot filter problems? How to prevent them

Soot filter problems? How to prevent them

Has a mechanic ever sent you out on the highway? He probably did this because there were problems with your particulate filter. If you have a diesel car that you don't drive much on the motorway, you should read this post about particulate filters and DPFs. This filter is located in the exhaust system and removes particles and pollutants formed during combustion. These particles are also known as fine dust and represent a health risk. Most diesels from after 2005 are equipped with a particle filter. These are mandatory from that year of construction so that they could comply with the Euro 4, 5 and 6 emission standards. 

How does a diesel particulate filter work? 

The particulate filter traps the harmful particles so that they can be burned later during the filter regeneration process. This converts them mainly into carbon dioxide and water.Filter regeneration takes place every 300 kilometres. A car with a particle filter is equipped with an electronic control unit that calculates the volume of particles accumulated and indicates when the process to remove them should ideally take place. To remove the particles, the particulate filter must operate at more than 400 degrees Celsius. If this is not the case, the filter may become clogged and have problems retaining the aforementioned particles. 

This is quite common in the situations below:  

  • if you only drive in the city, 
  • if you usually do not drive more than 60 kilometres per hour, 
  • if you use your car mainly for short trips or if your engine is idling a lot.

Good maintenance alone is often not enough

A particulate filter can cause problems, even with regular maintenance. The particulate filter light or emission fault will probably come on at some point if the car is driven many short distances. If this happens, you may also experience loss of power and an increase in fuel consumption.

"It may seem unfair: why is this light on, when you always maintain your car properly!" 

Cause of emission failure 

The reason why your vehicle does not remove the solid particles is because the particulate filter cannot regenerate because the exhaust does not get hot enough. So the particles accumulate in the filter and block the exhaust. In other words, your car is choking and screaming for help.

Fortunately, there is a simple solution 

Prevention is better than cure. If you regularly drive small distances, it is advisable to drive for at least 30 minutes on the motorway, and not at too low a speed. Just keep to the maximum speed of 130 km/h. The car may make a jolt. Don't worry, this only means that your exhaust has been cleaned and your car is now back to normal. The power of your engine will go back up and you will use less fuel.
So if you do a lot of city driving, regularly cover short distances or usually drive no more than 60 kilometres per hour, make sure you set aside a little time each week for your car. If this is not possible, try to squeeze a little 'car time' into your busy schedule every 200 or 300 kilometres. Regularly take a stretch of motorway where you are allowed to drive at 130 km/h. This reduces the chance of the particulate filter becoming clogged and an emissions warning light coming on. 

A diesel or petrol car?

Buying a diesel or petrol car?

There has been a lot of talk about diesel cars lately. Porsche has withdrawn its diesel models and no longer offers them, and the diesel offerings of Toyota is now also limited to its pickups and SUVs. Much of the controversy surrounding diesel stems from widespread media coverage of emissions scandals and negative government attention. This has led to a dramatic decline in diesel car sales. But does this mean you shouldn't consider buying one yourself?

When is a diesel car more advantageous

Ultimately, your choice of car comes down to petrol, diesel, hybrid or electricity, with the latter expected to provide the mid- to long-term answer to our personal transport needs. However, for a large number of motorists, diesel still makes sense.

Depending on how many miles you drive per year, a diesel can still be very attractive. The tipping point is still around 20,000 kilometres per year. If you decide to buy a used car, the difference can increase even further, as diesel cars have fallen out of favour due to negative media attention. If a 3-4-year-old diesel car is 2,000.00 euros cheaper, it will take an average of 3 years to recoup the difference in road tax. Not to mention the difference in fuel price and consumption.

What are good diesel models to buy?

There are traditionally a number of well-known brands that have developed the diesel engine to very great heights. These are the VAG group, BMW, and the French brands. The diesels of a few years ago often had a capacity of 1500 to 2000 cc and could easily achieve 1:20 with a normal driving style. Audi Like other brands, we have also developed a number of 3 cylinder engines, which can even reach 1:25. So you can drive 1000 kilometres on a 40 litre tank!

The only things you can't control with a diesel are the road tax and whether or not diesels are allowed in city centres. It will probably be another five years before younger diesels are banned from city centres, but be warned, in the long run this could be a problem if you live near one.

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