What does FSI engine mean, its advantages and disadvantages

FSI engines: the pros and cons of FSI engines, what are they

As soon as the gasoline engine was invented, the designers were constantly addressing the issue of improving its efficiency. The 20th century, its second half was marked by many design decisions in this area.

In the 90’s of the 20th century, Japanese engineers from MITSUBISHI offered to equip gasoline engines with the innovative GDI (Gasoline Direct Injection) system. The design feature of the system is that the fuel injector is located directly in the combustion chamber. However, exactly GDI was not widespread, due to the fact that the cost of operation was quite high, and the increase in power and efficiency was minimal. Later, such systems were taken as a basis for new generations of injection systems, and today we can observe a new generation of GDI systems on modern Japanese cars. The FSI engines came a little later.

What are FSI engines . The working principles of FSI engines

In Europe, in contrast to Japan, to a similar, but we note, not the same system, the designers have addressed in the early 2000s. The main work on the subject of direct injection began to conduct engineers at Volkswagen. Designers of the company took into account the mistakes of Japanese engineers, offering direct injection system FSI. The very name of the system hides its main difference from the GDI system. FSI-Fuel Stratified Injection is “layer-by-layer” fuel injection.

The system is structurally similar to the aforementioned GDI, but Volkswagen engineers added complete electronic control of the fuel-air mixture. This has entailed a complication of the system as a whole, but the increase in power and efficiency of the engine has already made solid 15%.

Differences of FSI engines from TSI , GDI and others

Today, almost all major manufacturers are using FSI-like systems in their engines. Each manufacturer has a technology that has certain design differences.

For example, the TSI system implies the combined use of direct injection together with a turbocharger, TOYOTA uses a system D4-S, which combines technologies of distributed and direct injection. MAZDA uses SKYACTIV technology, where direct injection and high compression ratio are combined.

Short list of names of automakers and systems using the technology of direct injection.

Toyota – D4/D4S; Mercedes-benz – CGI; Mitsubishi – GDI; Nissan – NEO DI;

Renault – IDE; Alfa Romeo – JTS; PSA Peugeot Citroën – HPi; Mazda – DISI/ SkyActive; Ford – EcoBoost; Volkswagen, Skoda, Audi – FSI, TSI;

Opel – direct, SIDI (Spark Ignition Direct Injection); Honda – I-CDTI and others.

Vehicle brands using FSI

FSI technology was developed by VAG engineers, so FSI technology was spread on the models of the manufacturer. Engines equipped with the FSI system were installed on AUDI, SEAT, Škoda, and of course Volkswagen.

Advantages (pros) of FSI engines

The main advantages of engines equipped with FSI are:

  • High efficiency compared to standard engines.
  • Less fuel consumption.
  • Less harmful emissions.
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Disadvantages (disadvantages) of FSI engines

The high design manufacturability of the FSI engine, does allow to get more power from the engine while reducing fuel consumption. But the use of technology FSI, has a downside.

The fact is that an engine equipped with FSI technology from the peculiarities of design, very demanding to the quality of service and fuel quality.

The FSI engine requires constant attention from the car owner.

First of all, because of the location of the fuel injector directly in the cylinder. Such a design is prone to increased contamination. This, in turn, causes engine malfunctions. Such as difficult starting, ignition skips, misfiring and increased fuel consumption. In critical cases, this can cause irreversible consequences, which later lead to costly repairs.

Preventive measures to clean the injectors allow you to avoid this. Of course, removing the injectors and cleaning them on the bench is quite expensive. The manufacturer itself, VAG, strongly recommends using special fuel additives to clean the fuel system of FSI engines. Of course, everyone is well aware that the manufacturer itself does not produce additives. And those additives that are sold under its brand are sometimes very expensive. A car owner should pay attention to quality products of famous manufacturers. The market today is oversaturated with various automotive chemicals.

He should choose a really necessary and, what is more important, qualitative product, which will give a real result after its usage.

The German company LIQUI MOLY is the leader in production of automotive chemicals and additives. The range of fuel additives allows to choose the product for the particular situation. For owners of cars with FSI technology LIQUI MOLY offers a special fuel additive that is tailored specifically to the engine. The Direkt Injection Reiniger direct injection system cleaner contains a detergent package that works at elevated temperatures and removes all common contaminants from the spray nozzles.

The result of the cleaner’s work

Please note that the cleaners for common rail injection systems are not effective on direct injection systems.

Troubleshooting for FSI engines

Unfortunately, maintenance of the direct injection injectors is not the only problem with the FSI system. The fact is that the design of the engine is such that the intake valves are also exposed to increased contamination. This problem is more serious and already requires intervention of the qualified mechanics. The matter is that by virtue of design features, it is impossible to influence on deposits by means of additives. In this case, a partial disassembly of the engine is necessary.

Prevention of malfunctions of FSI engines

Preventive maintenance helps to significantly reduce the amount of contamination and qualitatively increase engine life, in general. The use of additives keeps the system clean, reduces contamination and thereby increases service life. In the case of FSI systems and the like, a whole set of care and maintenance measures must be taken.

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To clean the injectors use: Direkt Injection Reiniger.

To clean the intake pipe and keep the air shutters working: Pro-Line Drosselklappen-Reiniger.

To remove moisture from the fuel tank: Fuel Protect

To improve fuel lubricity and maintain low and high pressure fuel pumps: Langzeit Injection Reiniger

Should I buy cars with FSI engines?

Cars equipped with the FSI system attract car owners with dynamics and economy. But on the other hand there is a lot of negative feedback regarding the operation of such cars. Practice shows that with proper care and proper use of automotive chemicals, it is possible to avoid costly investments in repairs.

The bottom line is .

Concern VAG is a company that looks into the future. Every year it offers car owners new models of cars equipped with the most modern engines. And the new TFSI system came to replace the FSI system. It also has its own peculiarities in operation. And the project to develop motors with the FSI system is still suspended.

The FSI engines and their development is one of the revolutions in the automobile industry. They have quite concrete and tangible advantages. But the downside of their use is costly repairs (primarily to the injectors). To avoid high costs and extend the life of FSI engines and injectors, these systems should be serviced. The easiest and cheapest way to do this is to use fuel additives.

VW AG: Excerpt from self-study material on the 2.0 TFSI engine

FSI engine

In the broad list of power units of the German auto giant VAG (Volkswagen AG) engines FSI, MPI, TSI (TFSI), TDI and a number of other units continue to enjoy great popularity due to their technology and unique characteristics. These engines were and are still being installed on different models of cars under the brand Volkswagen, Audi, Skoda, Seat and other brands within the concern VAG. Today, the above versions of the engines can be found on cars of different years of manufacture. In our articles we have already told our readers what are the TSI engines, which can be observed everywhere under the hood of Volkswagen, Audi and other brands. In this article we are going to talk about another popular motor, which is known as the FSI, and to consider in detail the principle of the FSI engine. At the same time the topic of oil selection for this type of internal combustion engine, common malfunctions and repair of the specified unit will be touched upon.

FSI engine: what is it

First of all, the transcription “FSI engine” is an abbreviation for Fuel Stratified Injection, which literally means layer-by-layer fuel injection. The main difference between this ICE and the now well-known TSI is the absence of turbocharging on the FSI version. In other words, this line includes uncharged (atmospheric) FSI gasoline engines with direct (direct) fuel injection.

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The FSI engine is not a “fresh” development, since the ready-made unit as the first test samples appeared back in 1998. Two years later, this motor began to be installed in series on Volkswagen models. Note that as of 2016, the last Volkswagen model with FSI remains the Touareg 4 WD off-road car. On other models, the FSI engine has now given way to a TSI (TFSI) or MPI version.

FSI engines: disadvantages and main advantages

Let’s start with the main pros and operating principles. A distinctive feature of the atmospheric engines of the FSI line can be considered the implementation of fuel injection and the scheme of the power system device. The fact is that the fuel supply system on such engines has structurally received two loops at once. In the first circuit the pressure is low, in the second one it is higher.

The contour with low pressure in the list of components has

– fuel tank; – petrol pump; – fuel filter; – bypass valve; – fuel pressure regulator;

High pressure circuit design implies availability of:

– high pressure fuel pump; – high pressure lines; – distribution lines; – high pressure sensor; – fuse valve; – injector nozzles;

The construction also includes an adsorber and a special valve for blowing it out.

On simple gasoline units the fuel injection is implemented in such a way that the fuel is fed to the intake manifold, and on the FSI engines the fuel is injected directly into the combustion chamber (direct injection). Injector injectors on these engines have 6 holes, which allows the most efficient distribution of fuel in the combustion chamber.

Air is supplied to the cylinders separately via a damper. As a result the best possible mixture formation and homogeneity of the fuel-air mixture can be achieved. The mixture combusts completely and evenly in the engine giving the maximum energy to the piston in different operating modes of the internal combustion engine. For this reason FSI engines provide better acceleration dynamics, are highly environmentally friendly and economical. In some cases such engines save up to 2.5 liters of fuel per 100 km compared to their simple counterparts in the same conditions. Let’s return to the features. As mentioned above, for the smooth operation of a gasoline engine with direct injection, engineers have separately introduced a high-pressure circuit in the FSI design. This pressure is necessary for the most precise and economical injection.

The injection pressure is created by a high-pressure fuel pump, which draws fuel from the low-pressure circuit. This design is reminiscent of a diesel engine. Moreover, the high-pressure fuel pump does not pump fuel constantly, but as needed for a particular operating mode of the unit.

In other words, during sudden acceleration and increased loads, the pressure rises to 0.5 MPa, while during coasting, the pressure in the circuit can be as low as 0.05 MPa. A separate electronic control unit, as well as a low-pressure sensor, allows such flexible pump control. The dynamic operation of the electronic control systems makes it possible to supply a strictly limited amount of fuel to the cylinders, depending on the operating mode. In other words, unnecessary enrichment or depletion of the fuel-air mixture is avoided. In parallel, injection is layer-by-layer, i.e. double injection. This means that fuel is metered between the injection and compression strokes. Such a solution makes it possible to save fuel and reduce the toxicity of the exhaust before the engine and catalytic converter are fully warmed up, since an enriched mixture is usually injected into the cylinders when the engine is cold.

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Disadvantages of the FSI engine

To begin with, any direct injection engine is highly sensitive to fuel quality. Along with this, it is necessary to be careful about the quality of fuel filters and strictly follow the schedule of replacements. The FSI engine in question is no exception in this case.

– Poor fuel quality often causes problems with the fuel equipment on this engine. Nozzles need to be constantly cleaned, since minor problems with injection later develop into serious breakdowns. Also, in motors of this type, spark plugs should be changed regularly and their condition should be monitored separately. – If we take into account the common malfunctions and FSI engines, problems in this line may occur with cold starting. The culprit is considered all the same layer-by-layer injection and the engineers’ desire to reduce the toxicity of the exhaust during warm-up.

In other words, the unit can simply not start in severe frosts. This phenomenon does not occur in all cars with this engine, as the manufacturer has eliminated the error in later versions, changing the firmware of electronic systems.

– Also, owners note greatly increased fuel consumption during trips when the motor of this type has not yet reached operating temperatures.

On the example of the common 2.0 liter FSI, other problems inherent in this engine become apparent.

– As a rule, a significant amount of fouling accumulates on the intake valves between 100,000 and 150,000 km. In this case, the soot on the valves causes the engine to be unstable and noisy, the power drops, and the consumption increases. Such fouling in some cases can only be removed mechanically, that is, disassembly and repair of the FSI engine is needed.

Let’s add that such a problem of increased sooting is more relevant for early versions of the unit, as later the manufacturer has changed the firmware in the fuel control units. At the same time, it is still impossible to exclude the increased formation of carbon monoxide with respect to all modifications of this unit.

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– It is also necessary to mark out the increased consumption of engine oil, both on earlier versions, and on later ones. The main symptom of obvious problems becomes the fact that the level of lubrication rapidly decreases. In this case, diagnostics is often necessary, and the frequent verdict is an engine overhaul.

As for the question of consumption and which fsi engine oil is better to pour, the main condition is to stick to the tolerance of VW 504 00/507 00. The seasonality has to be taken into account individually, as too liquid oil (e.g. 0W-30) can be very high in consumption. For this reason, many owners of this motor stop at 5W-30 when selecting a lubricant.

– In some cases it is also noted that the catalytic converter quickly fails, there are problems with the operation of lambda probes. Also malfunctions occur with camshafts and variable valve timing mechanism, ESD sensors fail. The slightest malfunction in the unit leads to the fact that the dashboard lights up “ceck” and the engine requires diagnosis. – Different versions of the FSI can have both a chain drive timing and a timing belt. Given the fact that the unit is quite technological, the breakage of the timing belt in this case can lead to very serious consequences, that is, get off only with the replacement of bent valves will not work.

What will result

1. If you look back, in 2000, FSI with a working volume of 1.4 liters took the honorable place in its class of the best unit. Six years later, the new 2.0 FSI was once again praised for its outstanding acceleration, good response at all rpm, lower emissions and fuel economy.

However, the engine has since been actively superseded by other counterparts and developments. Moreover, today FSI is the version of the power unit, which was actually abandoned by the manufacturer itself. The reasons for this are obvious, as the engine is atmospheric, while having a complex design, demanding fuel quality and quite expensive to repair.

3. With this in mind, it becomes clear why its budget car models VAG now uses a simpler and cheaper MPI, and on the basis of the technological FSI manufacturer has built a whole line of newer and more efficient turbocharged TSI (TFSI) engines.

In conclusion, we should add that the FSI can not be considered unsuccessful or problematic. A large number of its inherent failures and malfunctions are no less common in other engines, similar in design features and characteristics.

As practice shows, with proper care, timely maintenance and maintenance of the normal working capacity of all elements such an engine easily crosses the average mark of 200-250 thousand km. without any major repairs, pleases the owners with stable operation, confident acceleration and fuel economy.

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