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.