We will talk about the design of an internal combustion engine with multipoint injection, because this is how the decoding of the abbreviation MPI (Multi Point Injection) sounds in translation. Before the advent of gasoline power units with direct injection (FSI, TSFI,), it was the MPI engine that was installed on the entire model range of Volkswagen, Seat, Skoda, Mitsubishi, Renault, Ford and cars of many other manufacturers. Consider the device, the principle of operation and design features of the multipoint injection system for valves.
Design
The device of the Mitsubishi Motors multipoint injection system is shown schematically. The design is quite typical, so you can see almost identical structure on Volkswagen, Skoda cars. The main difference will be in how the amount of air is calculated. The diagram shows a design using an absolute pressure sensor (MAP) and a temperature sensor (DTV). Also, in MPI engines, the amount of air entering the cylinders can be calculated by a mass air flow sensor (MAF) and a Karman-type sensor. 
The main components of the electronically controlled MPI petrol injection system are:
- fuel supply system;
- ignition system;
- air calculation system;
- exhaust gas toxicity management systems.
Basics of the operating principle
Requirements to be met by the air-fuel mixture of a gasoline engine:
- be in a gaseous state. In other words, for efficient combustion, gasoline must completely evaporate before the TPVS is ignited;
- be homogeneous. The gaseous state contributes to good mixing of the fuel with the oxidizing agent (oxygen, which is in the air). Uneven mixing in areas with a large amount of oxidant increases the risk. In areas with significant re-enrichment, gasoline will not completely burn, which will entail a decrease in engine efficiency;
- the amount of fuel supplied must correspond to the mass of air entering the cylinders. For the most complete combustion of TPVS, it is necessary to mix 1 kg of gasoline with 14.7 kg of air. By increasing or decreasing the proportion of air, we get an economic (lean) or power (rich) composition of the fuel mixture. But the range of variation in the proportions in the composition is quite narrow, which partly explains the relatively low efficiency of a gasoline engine with an MPI injection system (for example, in comparison with).
Supply system
Modern engines are increasingly equipped with hybrid injection, in which individual injectors inject fuel both into the valves and directly into the combustion chamber. Manifold injectors are used as an auxiliary system to flush deposits from intake valves.
Features of Volkswagen, Skoda mots
You can find many unflattering reviews about 1.6 liter MPI engines, which were installed on many VAG-Group models (Skoda Yeti, Octavia, Volkswagen Polo Sedan). Most likely, most of them will be about CFNA models, which, with relatively low mileage, begin to knock on the cold and consume oil. But this is connected not with the distribution injection on the MPI valves, but with the design features of the cylinder-piston group.
Judging by the reviews, to a lesser extent the problem of knocking on a cold one touched 1.6 CWVA engines. The payment for this has become. Volkswagen engineers compensated for the increased load on the CPG by the design of the oil scraper rings, which are required to leave a large amount of oil on the cylinder walls. Andrei Krutsko will tell you in more detail about the problem of the naturally aspirated MPI engines of Skoda, VW.
Surely everyone knows what a motor is in a car. but our today's article is devoted to a specific unit, about which we will try to tell from "A" and "I"
The end of the last century and the beginning of a new one became a period of heightened interest in MPI gasoline engines. The interpretation of this abbreviation sounds like Multi Point Injection. The extraordinary fuel injection scheme has served as a good demand for cars with such engines. This scheme was created according to the multi-point principle.
Individual injectors in each cylinder ensure the most uniform distribution of fuel in the cylinders. This design development, namely the launch of multi-point injection engines, was taken over by Volkswagen. Due to which later MPI engines appeared.
The emergence of such power plants constituted an alternative to carburetor engines. To better understand the MPI engine, you need to carefully analyze its competitive features.
Modernity of Multi Point Injection engines
There is no future for MPI engines, as it looked a few years ago; many even believed that the production of this type of engine had been suspended. The radical development of automotive developments and technologies very quickly forces us not to remember yesterday's quality benchmarks.
In fact, this is what happens with MPI engines, many in the industry argue that efficiency and environmental friendliness are outdated.
But these conclusions are mostly true only for the European markets, and as for the Russian ones, here it all looks in part. Since the real potential of these units has not yet been fully revealed by domestic motorists.
Manufacturers relying on foresight do not let this technology die and are constantly introducing it on cars intended for Russian roads. For example, Skoda Yeti or Volkswagen Polo. The most memorable were the representatives of the MPI system with engines, the volume of which was 1.4 or 1.6 liters.
Design features of the MPI engine
The complete absence of a turbocharger is another significant feature of this system, along with the multipoint injection system. In the design of these engines there is a conventional gas pump, which, under a pressure of 3 atmospheres, supplies fuel to the intake manifold for subsequent mixture formation and supply of a ready-made composition through the intake valve.
This scheme of work is very similar to the scheme of operation of carburetor engines. With one difference, there is a separate nozzle for each cylinder.
Another unusual feature of the engine's Multi Point Injection system is the presence of a water cooling circuit for the fuel mixture. This is due to the fact that in the area of the cylinder head there is a very high temperature, and the pressure of the incoming fuel is very low, because of this there is a high probability of a gas-air lock and, consequently, boiling.
Inherent advantages of MPI
Before switching to a car with MPI, many motorists who are more or less familiar with this system will think very well about obtaining a set of advantages due to which multipoint injection installations have earned a vocation in the world.
Simplicity of the device
This does not mean that such systems are simpler compared to carburetor models. If we compare the TSI model, which has a high-pressure fuel pump and turbochargers in its design, then naturally superiority is evident. And the cost of the car will be lower and reduced operating costs and the ability to carry out self-repair.
Undemanding fuel quality inquiries
It is not possible to guarantee the proper quality of fuel and oils everywhere and always, which is very typical for Russia. The use of low-octane gasolines below 92 does not affect the performance of MPI engines, since they are very unpretentious. The minimum mileage of cars without breakdowns, according to the developers, is 300,000 km, subject to timely replacement of oil and filter elements.
Minimum overheating probability
The ignition timing is adjustable. The presence of a system of engine mounts, which is designed to use rubber mounts. Of course, this is not directly related to the engine, but it still matters for the performance of the engine and the comfort of the driver.
Because the supports dampen vibrations and various noises that occur when driving. An interesting feature is that the supports are automatically adjusted for various engine operating modes.
Typical disadvantages of MPI
All the disadvantages of this engine are expressed precisely by its design features. The connection of fuel with air occurs in the channels, and not directly in the cylinders. Accordingly, there is a limitation of the capabilities of the intake system. This is expressed in a lack of power and a rather weak torque.
Proceeding from this, decent dynamics, sporty throttle response, hot drive are not obtained. In modern cars, the presence of eight valves, as a rule, is not enough, so all these characteristics increase. If you characterize this car with such a system, then it will quite pass for a family and quiet transport.
That is why such cars are no longer in demand and recede into the background into the past. Why is this happening, i.e. the world made an assessment of the qualities of this system and decided that this was not enough for him and the designer's developers began to design more modern motors in terms of power. But no, there are unexpected surprises in the automotive industry.
The developers of Skoda, having developed the Russian version of the Yeti SUV for family use, in 2014 deliberately abandoned the turbocharged engine with a volume of 1.2 in favor of the MPI engine with a volume of 1.6 and 110 hp.
As the developers of the well-known world concern stated, this engine has practically nothing in common compared to the old 105 hp model. It suits TSI models best, but lacks direct injection and turbocharging.
Summarizing
All of the above indicators significantly affect the departure of engines from the world market with the MPI system. These days, many car enthusiasts prefer the more powerful modern cars, which are steadily increasing in pace.
The need to equip machines with more powerful units significantly underestimates the coefficient of demand for Multi Point Injection engines. Compared to them, this motor is rather weak. But it is still too early to write off the MPI engine completely, since the developers of the Skoda Yeti are trying to use it to the fullest on Russian roads.
Few car owners know what an MPI engine is. This abbreviation stands for Multi-Point-Injection, and the engine itself is a design with a multi-point fuel injection system. To summarize the data, the peculiarity of such a motor is that each cylinder of the power plant receives its own injector-nozzle. This technology was invented and implemented
Where is it implemented?
Now you have a little understanding of what this MPI engine is. For the first time, this technology has been successfully implemented in the Polo model. Later "Golf" and "Jetta" also received such engines.
Note that from the engine range, such engines are outdated. Nevertheless, they are practical and reliable. Many experts argue that today such power plants do not meet modern economic and environmental standards. In addition, quite recently, one could say that the manufacturer has stopped the production of such motors. The last car to receive an MPI engine is the Skoda Octavia of the second series.
However, the technology has recently been revived, it has become in demand. In the fall of 2015, at the Kaluga plant, the concern launched a production line for these engines, where they began to produce motors of the EA211 series.
Peculiarities
What features they have has already been written above. These are motors with a multi-point gasoline supply system. However, those in the know can say that TSI engines also use a multi-point fuel delivery system. Therefore, in this case, it is appropriate to talk about other distinctive features - there is no supercharging in the Skoda and Volkswagen MPI engines. This means that there are no turbochargers that would pump the fuel mixture into the engine cylinders. The most ordinary gasoline pump is used here, which pumps gasoline from the tank to the start-up manifold, while creating a pressure of only 3 atmospheres. In the manifold, the fuel is mixed with air and is drawn into the combustion chamber through the intake valve. Actually, the system is very similar to the principle of the carburetor, and there is no direct injection of fuel into the cylinders (as in FSI, TSI and GDi engines).
Now you have a better understanding of what MPI engines are. It is appropriate to answer the second feature - the presence of a water cooling system. Thanks to it, the fuel is cooled. This is necessary due to the increased temperature conditions at the cylinder head. Since the temperature is high there and the fuel is supplied at low pressure, there is a possibility that the fuel mixture can boil, leading to the formation of gas air pockets.
Dignity
MPI motors can boast of unpretentiousness to the fuel used and efficiently run on 92nd gasoline. Also, the design of such an engine is very durable, and its mileage without any intervention and repair is on average 300 thousand kilometers. Of course, it is necessary to change filters and oil on time. 1.6 MPI (and other car models) is simple in design, and in case of any breakdown, it can be inexpensively repaired at a service station. In this case, the design feature of such motors compares favorably with more complex TSI-engines with high-pressure pumps and turbochargers. Also MPI motors overheat less.
The last more or less pertinent plus is rubber mounts located under the engine. They help reduce noise and shake while driving.
Minuses
According to the reviews, MPI engines are less dynamic, and there is a reason for this. Due to the fact that gasoline is mixed with air in the exhaust ducts (before being fed into the cylinders), these engines are limited. Also, the eight-valve system with a timing set makes it clear that the motor lacks power. Therefore, these motors are not designed for quick start and acceleration.
The second drawback is inefficiency. Multipoint injection is inferior in efficiency and economy to supercharging with direct injection of fuel into the cylinders. As mentioned above, this technology is implemented in TSI engines.
MPI engine - solution for Russian roads
In addition, cars with such engines are better suited for Russian operating conditions. The fact is that the quality of the fuel sold at some gas stations leaves much to be desired. However, for MPI engines, even gasoline with a higher sulfur content is perceived easily, and the engine perfectly processes this type of fuel. And the robust design of the power plant itself provides additional reliability and protection from unnecessary mechanical stress that occurs when driving on bad roads with potholes. So it is fair to say that MPI engines are better suited for Russia. Perhaps because of this, a production line for the production of such motors was established at the Kaluga plant. Now we have finally figured out what an MPI engine is and what its features, advantages, and disadvantages are.
Finally
If we compare the pros and cons, then we can conclude that such motors are quite competitive for themselves. An indirect confirmation of this is the abandonment of the 1.2-liter TSI engines by German manufacturers in favor of the unassuming 1.6-liter engines with MPI injection technology.
Can you recommend it to car buyers? Quite! This is a pretty good technology from Volkswagen that deserves a chance at life. This is confirmed by numerous customer reviews.
MPI engines are gradually becoming a thing of the past, so it is less and less common to meet a car enthusiast who understands what it is about when they call this abbreviation. Those who have changed a lot of cars or are interested in cars in general know about it.
Having replaced carburetor engines, becoming the next step in the development of the automotive industry, this type of engine is now giving way to advanced developments. Today, many people think in advance which engine should be on a personal car: TSI, FSI or MPI. Although, until now, many experts consider the latter the most practical, reliable and trouble-free in the family of injection engines.
FSI is considered a more modern development, the next step after MPI. The BSE engine appeared in 2005 and is famous for being well tolerated by the poor quality of domestic fuel.
Did you know? The abbreviation MPI comes from the term Multi Point Injection, which means multipoint fuel injection. The motor was actively used at the Volkswagen concern. It was gradually introduced at the Skoda subsidiary. The motors were also installed there for the last time - on the Yeti and Octavia models.
It should also be explained what MPI and TSI are. If the first term means an internal combustion engine, in which each cylinder has its own injector, then TSI has different interpretations.
So, initially, the abbreviation meant double supercharging and stratified injection: Twincharged Stratified Injection. But recently, the abbreviation TFSI has become increasingly used, in which the additional letter F stands for Fuel - fuel.
You can often find another abbreviated name of the engine - MPI DOHC, which means it is easy to understand if you know that the term DOHC refers to engines in which there are 2 camshafts and 4 valves in the cylinder head.
Principle of operation
The MPI fuel injection system delivers fuel from multiple points simultaneously. Each cylinder has its own injector, and fuel is supplied through a dedicated exhaust channel. But what distinguishes the MPI engine from the TSI, which is also equipped with a multi-point fuel supply, is lack of pressurization.
The fuel mixture is supplied to the cylinders not with the help of turbochargers, but with the help of a gas pump. It pumps gasoline into a special intake manifold under pressure of three atmospheres, where it mixes with air and is also sucked into the cylinder through the intake valve under pressure.
Schematically, the engine looks like this:- The fuel pump pumps fuel from the tank to the injector.
- A signal is sent from the electronic injection control unit to the injector, which passes fuel into a special channel.
- The mixture is directed to the combustion chamber.
The hydraulic drive control system consists of a clutch with a grease fitting and a system that limits trims. It includes rubber mounts that can independently adjust to the engine operating mode, reducing noise and vibration during operation. The engine has 8 valves: 2 for each of the cylinders, as well as a camshaft.
Did you know? The most common engines are the MPI 1.4 with 80 horsepower and 1.6 with 105 horsepower. But automakers are still gradually abandoning them. The only ones who still use engines of this type are the Dodge and Skoda companies.
Dignity
The engine has several advantages, the main of which is - simplicity of the system. This makes it easy to repair and maintain. For repairs, it is not always necessary to completely disassemble the entire structure. It can run on 92 gasoline.
In addition, its overall construction is very robust. In most cases, you can drive up to 300 thousand km without repairing the engine. Of course, if you maintain it properly: change the oil and filters on time.
disadvantages
However, it was the design features of the MPI engine that provoked its shortcomings. The intake system has very limited capabilities, since the fuel is combined with air not in the cylinders, but in the channels. Therefore, the motor has a weak torque and low power. In addition, 8 valves are considered insufficient for today's vehicles.
In general, this type of engine is only good for a low-speed family car. Apparently, therefore, car manufacturers have been increasingly abandoning it lately.
Important! Today, only a few companies use this type of motor in their vehicles. In addition, repairing it is quite expensive. This must be taken into account when choosing a car.
Although there are attempts to upgrade this engine. For example, in 2014 Skoda installed an improved engine of this type on the Yeti, designed specifically for the Russian segment. He received a power of 110 horsepower.
American developers are also engaged in modernization, but nevertheless, in the confrontation between power and reliability, manufacturers and motorists more often choose the former.
The forthcoming publication is intended for experienced drivers who have changed a lot of vehicles. Today, an engine labeled MPI is considered a kind of rarity, supplanted by more advanced innovative developments. And at one time, such a power unit was a novelty of advanced technologies.
The information provided will help you better understand the device of this motor, weigh its disadvantages and evaluate its advantages. Also in this article you can find a detailed description of the principle of operation of the complex mechanism with the MPI index.
What was good about the MPI engine, memories of achievements in the field of automotive industry
Some confirmation of the well-known statement that nothing lasts forever in our ghostly world is the gradually disappearing popularity of the power unit with the MPI marking. At one time, it was considered a very successful replacement for carburetor engines, a definite innovation in the modern automotive industry, an advanced stage in its development.
Today, most motorists look at each other in bewilderment at the mention of the abbreviation MPI, since contemporaries are more familiar with the TSI, FSI engines or the BSE that appeared in 2005. It should be noted that the latest engine model is characterized by excellent portability of domestic fuel, whose quality leaves much to be desired.
In the line of injection engines, the unit in question occupies a worthy place, characterized by extreme practicality, reliability and reliability. At the time of its launch into production, it was considered the forefront of the domestic automotive industry.
Than the drivers with considerable experience remembered the MPI injection engine. What are the features of its principle of operation, what are the indisputable advantages and annoying flaws. Further information will answer the questions of curious motorists.
The principle of operation of the MPI power plant
First, you need to explain to uninformed readers that the abbreviation MPI stands for an internal combustion engine, each cylinder of which corresponds to a separate injector. The name MPI DOHC is much more common. Here the second part of the name indicates two camshafts with four valves.
The principle of operation of the main mechanisms that make the MPI engine function is quite simple. Nevertheless, it deserves a separate consideration.
Fuel is supplied simultaneously from several points. As mentioned earlier, there is a separate injector for each cylinder and a dedicated exhaust port for fuel delivery. The multi-point fuel supply is also characteristic of the TSI engine, but it differs in the presence of pressurization, which is absent in the engine in question.
A special intake manifold is an intermediate link, where fuel is supplied under a pressure of three atmospheres by a special pump. A mixture of gasoline and air is formed in it, after which it enters the cylinders through the intake valve. The whole process is carried out at elevated pressure.
Briefly, the operation of the engine can be described in three stages:
- First, the fuel from the gas tank is pumped to the injector;
- After receiving a certain signal from the electronic control unit, the injector directs the fuel into a special channel;
- In this direction, the fuel mixture is delivered to the combustion chamber.
Some similarity in the principle of operation with the carburetor unit is leveled by the presence of a liquid cooling system. This is due to the excessive overheating of the space at the cylinder head.
A strong increase in temperature can cause the fuel that is there under low pressure to boil. The gases emitted during this process can form undesirable gas-air locks.
Another distinguishing feature of the MPI engine is the presence of a specific control mechanism for the hydraulic drive, consisting of a clutch equipped with a grease nipple, and a special system that sets certain limits for trims.
It is usually represented by rubber supports, a distinctive feature of which is the ability to independently adapt to the mode of operation of the power unit. Their main purpose is considered to be noise and vibration reduction during engine operation.
The design of the MPI engine also includes eight valves, located in pairs on each of the four cylinders. An important part of such an engine is the camshaft, which is considered an essential part of the system.
Advantages and disadvantages of MPI motors
First of all, it should be noted the undeniable advantages of the design of the unit in question, namely:
- The presence in the device of the power plant of the function of advancing the ignition process contributes to an increase in the sensitivity index of the throttle located on the gas pedal. This significantly expands the possibilities of driving a car;
- Water cooling of the gasoline-air mixture allows you to maintain an acceptable temperature in the engine, protecting it from the formation of gas-air jams;
- The advanced hydraulic drive control system makes it possible to significantly reduce the noise and vibration generated by a functioning motor.
Among other advantages of power units with the MPI marking, the following can be noted:
- Unpretentiousness to the quality of fuel. For domestic motorists, the possibility of using inexpensive AI-92 gasoline is especially attractive, which translates into significant savings in refueling;
- Reliability and strength of the structure. The manufacturer declared a minimum motor resource of 300 thousand km. However, trouble-free operation of the engine is impossible without periodic replacement of lubricants and filters;
- The extreme simplicity of the power unit is reflected in the cost and laboriousness of the repair.
You can't do without a fly in the ointment, which somewhat belittles the listed advantages of the MPI motor. In our case, a significant flaw in such engines is considered to be the power loss arising from the limited intake system. However, although the units under consideration lose their dynamism due to the presence of eight valves in the timing mechanism, a measured calm ride with their help is ensured.
Conclusion
Having considered in detail all the advantages of MPI engines, and carefully weighing the disadvantages, it becomes unclear why the manufacturer refused their widespread use. If earlier almost all Volksvagen car models were equipped with such motors, today they are installed only on the second generation Skoda Octavia.
The design of power units is considered outdated and is gradually being phased out, being replaced by high-tech innovations.
