In this article we will try to figure out what it is, what it is for and where the injector is located. Injector is a cognate word with the word injection, and injection is an injection. Although the injector bears little resemblance to a syringe, it also injects fuel into the engine cylinders. Strictly speaking, the injector is a nozzle that sprays fuel in small drops to enter the cylinders with a mixture of air and gasoline vapor. You say it does everything the same. Same, but not quite.
The carburetor jet works almost like spraying gasoline in its chamber. But gasoline is sucked into the carburetor by the engine piston, which takes about 10% of its power. Plus, it’s almost impossible to adjust the carburetor to an ideal state: it either overflows fuel, that the engine “chokes” and smokes, and part does not burn out, then it does not top up, and the engine works with dips and does not pull.
Gasoline is pumped into the injector using a special electric pump, and the mixing of gasoline and air vapors occurs in the cylinder combustion chamber itself. The amount of fuel is clearly portioned, and it depends on the amount required at the moment for optimal traction.
Where is the injector located?
In normal cases, the injector is installed instead of the carburetor, or rather, in general, in its place. As an injector, only one nozzle is used, which “serves” all cylinders, and fuel injection will be into the intake manifold, the so-called mono injection. There is only one advantage over the carburetor scheme here: the engine does not expend power on sucking fuel through the carburetor jet.
The system of multi-point or distributed injection is also made into the intake manifold. Thanks to the distributed injection, the fuel that enters each cylinder is better dosed. But still, only direct injection directly into the combustion chamber of the cylinder gives the best results, just like in.
Injector (injector) malfunctions are found both on and on engines. In the scheme of the power supply system of an injection engine, the nozzle is an element that is responsible for injecting an atomized portion of fuel into the combustion chamber at a certain pressure.
Accurate dosing, tightness and timely operation of the injection nozzle ensure stable and proper operation of the engine in all modes of operation. If the injector “pours” (let excess fuel pass at the moment when it is not required to be supplied), the efficiency of fuel spraying decreases (the shape of the torch is disturbed) and other malfunctions of the injector occur, then it loses power, consumes a lot of fuel, etc.
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What indicates a possible problem with the injector
We note right away that there can be many reasons for unstable engine operation, ranging from clogged, breakdown, failed spark plug or faulty coil to problems with, etc. Along with this, one of the main signs of a malfunction of the injectors is, as well as the consumption of gasoline or diesel fuel (depending on the type of engine), which increases markedly. It is also necessary to note the unstable operation of the internal combustion engine in idling mode, similar to the so-called "triple" of the engine.
When driving, one or more of the following symptoms may occur quite often:
- the presence of jerks, very slow reactions when you press the gas pedal;
- obvious dips and loss of dynamics when trying to accelerate sharply;
- the car may twitch on the go, when the gas is released, and also after changing the load mode on the engine;
It must be added that such a malfunction must be eliminated without delay, since problems with the injector negatively affect not only the life of the engine and transmission, but also the overall traffic safety. On a vehicle with defective injectors, the driver may experience serious difficulties when overtaking, on steep slopes, etc.
Self test of injectors
Let's start with the fact that automobile injectors are divided into several types, of which two types have found wide use at different times: mechanical injectors and electromagnetic (electromechanical) injectors.
Electromagnetic injectors are based on a special valve that opens and closes the injector to supply fuel under the influence of a control pulse from the engine. Mechanical injectors open as a result of an increase in fuel pressure in the injector. We add that electromagnetic devices are often installed on modern cars.
To check the nozzles with your own hands without removing it from the machine, you can use several methods. The simplest and most accessible way, which allows you to quickly check the injection nozzles without removing them from the machine, is to analyze the noise emitted by the engine during operation.
It is possible to determine a faulty injector by ear by the sound of the internal combustion engine if a muffled high-frequency sound is heard from the cylinder block. This indicates the need to clean the injector or a malfunction of the injectors.
How to check the power supply to the injectors
The specified check is carried out if the injectors themselves are in good order, but any of the injectors does not work when the ignition is turned on.
- for diagnostics, the block is disconnected from the injector, after which two wires must be connected to;
- the other ends of the wires are attached to the nozzle contacts;
- then you need to turn on the ignition and record the presence or absence of fuel leakage;
- if fuel flows, then this symptom indicates problems in the electrical circuit;
Another of the diagnostic techniques is to check the injector with a multimeter. This method allows you to measure the resistance on the injectors without removing them from the engine.
- Before starting work, it is necessary to find out what impedance (resistance) the injectors installed on a particular vehicle have. The fact is that there are injection nozzles with both high and low resistance.
- The next step is to turn off the ignition, as well as reset the negative terminal from the battery.
- Next, you need to disconnect the electrical connector on the nozzle. To do this, you need to use a screwdriver with a thin end, with which you need to snap off a special clip located on the block.
- After disconnecting the connector, we transfer the multimeter to the desired operating mode for measuring resistance (ohmmeter), connect the multimeter contacts to the corresponding contacts of the nozzle to measure the impedance.
- The resistance between the extreme and central contact of the high impedance injector should be between 11-12 and 15-17 ohms. If low resistance injectors are used on the car, then the indicator should be from 2 to 5 ohms.
If obvious deviations from the permissible norms are noticed, then the nozzle must be dismantled from the engine for detailed diagnostics. It is also possible to replace the injector with a known good one, after which the operation of the engine is evaluated.
Comprehensive diagnostics of the operation of injectors on the ramp
For such a check, the fuel rail will need to be removed from the engine along with the nozzles attached to it. After that, you need to connect all electrical contacts to the ramp and nozzles if they were disconnected before removal. It is also necessary to replace the negative terminal of the battery.
- The ramp must be placed in the engine compartment so that it is possible to place a measuring container with a printed scale under each of the nozzles.
- It is necessary to connect fuel supply pipes to the rail and additionally check the reliability of their fastening.
- The next step is to turn on the ignition, after which you need to crank the engine a little with the starter. This operation is best done with an assistant.
- While the assistant rotates the engine, check the efficiency of all injectors. The fuel supply must be the same on all nozzles.
- The final step will be to turn off the ignition and check the fuel level in the tanks. The indicated level must be equal in each container.
More or less fuel in the measured containers will indicate a malfunction of the injector or the need to clean one or more injectors. If the nozzle shows underfilling, then the element needs to be cleaned or replaced. Fuel leakage after turning off the ignition will indicate that the nozzle is “pouring” and has lost its tightness.
In addition to self-checking, you can use the injector diagnostic service at a car service. This operation is performed on a special test stand. Checking the nozzle on the stand allows you to accurately determine not only the efficiency of the fuel supply, but also the shape of the torch during fuel spraying.
How to clean the injectors yourself without removing from the engine
During the diagnostic process, a common cause of unstable engine operation is that the injection nozzles are clogged. There are several ways to clean nozzles, among which mechanical, ultrasonic or cleaning with special chemical compositions can be used.
In some cases, pouring a special injector cleaner additive into the fuel tank is enough to normalize the operation of the entire system. It is also recommended to spin the engine to high speeds with a certain frequency and accelerate the car to 110-130 km / h. on flat paths. In this mode, you need to drive 10-20 kilometers. Long-term operation of the nozzles under load allows for the so-called self-cleaning.
Finally, we add that the cleaning methods listed above allow you to remove only minor contaminants. A severely clogged injector must be cleaned mechanically, with pressurized compounds or ultrasonic cleaners. As for flushing the injectors, experts recommend flushing the injector every 30-40 thousand kilometers traveled.
Cleaning the injector should be done for prevention, and not after the appearance of signs of a malfunction. If the car is operated in urban driving mode on fuel of questionable quality, then the interval of preventive measures should be reduced in relation to individual operating conditions.
Read also
When and why you need to remove the fuel injectors from the engine. Removing nozzles on a gasoline and diesel engine: features of the dismantling process.
Now, on almost any gasoline engine in a car, an injection power system is used, which has replaced it. The injector, due to a number of performance characteristics, is superior to the carburetor system, so it is more in demand.
A bit of history
Such a power system has been actively installed on cars since the mid-80s, when environmental emission standards began to be introduced. The very idea of a fuel injection system appeared much earlier, back in the 30s. But then the main task was not in environmentally friendly exhaust, but in increasing power.
The first injection systems were used in combat aviation. At that time, it was a completely mechanical design, which performed its functions quite well. With the advent of jet engines, injectors have practically ceased to be used in military aircraft. On cars, the mechanical injector was not particularly widespread, since it could not fully perform the assigned functions. The fact is that the modes of the car engine change much more often than that of an airplane, and the mechanical system did not have time to adapt to the operation of the engine in a timely manner. In this regard, the carburetor won.
But the active development of electronics gave a "second life" to the injection system. And an important role in this was played by the struggle to reduce the emission of harmful substances. In search of a replacement for the carburetor, which no longer met environmental standards, the designers returned to the fuel injection system, but radically revised its operation and design.
What is an injector and why is it good
The injector literally translates as "injection", so its second name is an injection system using a special nozzle. If in the carburetor fuel was mixed with air due to the vacuum created in the engine cylinders, then in the injection engine gasoline is forced. This is the most fundamental difference between a carburetor and an injector.
The advantages of an injection engine, relative to carburetor ones, are:
- Economy of consumption;
- Best power output;
- Less harmful substances in exhaust gases;
- Ease of starting the motor under any conditions.
And all this was achieved due to the fact that gasoline is supplied in portions, in accordance with the mode of operation of the engine. Because of this feature, the air-fuel mixture enters the engine cylinders in optimal proportions. As a result, in almost all operating modes of the power plant, the maximum possible combustion of fuel with a lower content of harmful substances and increased power output occurs in the cylinders.
Video: The principle of operation of the injection engine power system
Types of injectors
The first injectors that were massively used on gasoline engines were still mechanical, but they already began to have some electronic elements that contributed to better engine performance.
The modern injection system includes a large number of electronic elements, and the entire operation of the system is controlled by a controller, aka.
In total, there are three types of injection injection systems, differing in the type of fuel supply:
- Central;
- distributed;
- Immediate.
1. Central
The central injection system is now obsolete. Its essence is that the fuel is injected in one place - at the inlet to the intake manifold, where it is mixed with air and distributed over the cylinders. In this case, its operation is very similar to a carburetor, with the only difference being that the fuel is supplied under pressure. This ensures its atomization and better mixing with air. But a number of factors could affect the uniform filling of the cylinders.
The central system was distinguished by its simple design and quick response to changes in the operating parameters of the power plant. But it could not fully perform its functions. Due to the difference in the filling of the cylinders, it was not possible to achieve the desired combustion of fuel in the cylinders.
2. Distributed
Multipoint fuel injection
The distributed system is currently the most optimal and is used on many vehicles. In this type of injection engine, fuel is supplied separately for each cylinder, although it is also injected into the intake manifold. To ensure separate supply, the elements that supply fuel are installed near the head of the block, and gasoline is supplied to the valve area.
Thanks to this design, it is possible to achieve compliance with the proportions of the air-fuel mixture to ensure the desired combustion. Cars with such a system are more economical, but at the same time the power output is greater, and they pollute the environment less.
The disadvantages of a distributed system include a more complex design and sensitivity to fuel quality.
3. Immediate
Direct fuel injection system
The direct injection system is currently the most advanced. It differs in that the fuel is injected directly into the cylinders, where it is already mixed with air. This system is very similar in principle to diesel. It allows you to further reduce gasoline consumption and provides more power output, but it is complex in design and very demanding on the quality of gasoline.
The design and principle of operation of the injector
Since the distributed injection system is the most common, we will use its example to consider the design and principle of operation of the injector.
Conventionally, this system can be divided into two parts - mechanical and electronic. The first one can additionally be called executive, because thanks to it, the components of the air-fuel mixture are supplied to the cylinders. The electronic part provides control and management of the system.
The mechanical component of the injector
Power supply system for VAZ 2108, 2109, 21099 cars
The mechanical part of the injector includes:
- fuel tank;
- electric ;
- gasoline cleaning filter;
- high pressure fuel lines;
- fuel rail;
- nozzles;
- throttle assembly;
Of course, this is not a complete list of components. The system may include additional elements that perform certain functions, it all depends on the design of the power unit and the power system. But these elements are basic for any engine with a distributed injection injector.
Video: Injector
The principle of operation of the injector
As for the purpose of each of them, everything is simple. The tank is a container for gasoline, where it is stored and fed into the system. The electric fuel pump is located in the tank, that is, the fuel is taken directly from it, and this element provides fuel under pressure.
To prevent overpressure, a pressure regulator is included in the system. From the filter, through it, through the fuel lines, gasoline moves to the fuel rail connected to all injectors. The injectors themselves are installed in the intake manifold, not far from the cylinder valve assemblies.
Previously, the injectors were completely mechanical, and they were triggered by fuel pressure. When a certain pressure value was reached, the fuel, overcoming the force of the injector spring, opened the supply valve and was injected through the atomizer.
The modern nozzle is electromagnetic. It is based on a conventional solenoid, that is, a wire winding and an armature. When an electrical impulse is applied, which comes from the ECU, a magnetic field is formed in the winding, which acts on the core, causing it to move, overcoming the force of the spring, and open the supply channel. And since gasoline is supplied to the nozzle under pressure, gasoline enters the manifold through the opened channel and sprayer.
On the other hand, air is sucked into the system through the air filter. In the branch pipe through which the air moves, a throttle assembly with a damper is installed. It is on this damper that the driver acts by pressing the accelerator pedal. At the same time, he simply regulates the amount of air supplied to the cylinders, but the driver has no effect on the fuel dosage at all.
Electronic component
The main element of the electronic part of the fuel injection system is an electronic unit consisting of a controller and a memory unit. The design also includes a large number of sensors, based on the readings of which the ECU controls the system.
For its work, the ECU uses the readings of the sensors:
- . This is a sensor that detects the remaining unburned air in the exhaust gases. Based on the readings of the lambda probe, the ECU evaluates how mixture formation is observed in the required proportions. It is installed in the exhaust system of the car.
- Mass air flow sensor (abbr. DMRV). This sensor determines the amount of air passing through the throttle assembly when it is sucked in by the cylinders. Located in the air filter element housing;
- (abbr. DPDZ). This sensor gives a signal about the position of the accelerator pedal. Installed in the throttle assembly;
- Power plant temperature sensor. Based on the readings of this element, the composition of the mixture is regulated depending on the temperature of the motor. Located near the thermostat;
- (abbr. DPKV). Based on the readings of this sensor, the cylinder is determined into which it is necessary to supply a portion of fuel, the time for supplying gasoline, and sparking. Installed near the crankshaft pulley;
- . It is necessary to detect the formation of detonation combustion and take measures to eliminate it. Located on the cylinder block;
- Speed sensor. It is needed to create impulses, according to which the speed of the car is calculated. Based on his testimony, the fuel mixture is adjusted. Mounted on the gearbox;
- Phase sensor. It is designed to determine the angular position of the camshaft. May not be available on some vehicles. If this sensor is present in the engine, phased injection is performed, that is, the opening impulse is received only for a specific injector. If this sensor is not present, then the injectors operate in pair mode, when the opening signal is sent to two injectors at once. Installed in the block head;
Now briefly on how everything works. The electric fuel pump fills the entire system with fuel. The controller receives readings from all sensors, compares them with the data stored in the memory block. If the readings do not match, it corrects the operation of the engine power system in such a way as to achieve maximum agreement between the data received and those entered in the memory block.
As for the fuel supply, based on the data from the sensors, the controller calculates the opening time of the injectors to ensure the optimal amount of gasoline supplied to create the air-fuel mixture in the required proportion.
If one of the sensors fails, the controller goes into emergency mode. That is, it takes the average value of the readings of the faulty sensor and uses them to work. In this case, a change in the functioning of the motor is possible - consumption increases, power drops, interruptions in work appear. But this does not apply to the DPKV, if it breaks down, the engine cannot function.
Equipment of this kind is used in all injection systems of engines - both gasoline and diesel. Today, modern engines use nozzles that are equipped with electronically controlled injection.
Depending on one or another method of injection, there are such types of nozzles as: electromagnetic, piezoelectric and electrohydraulic.
- Read also the article:
The design and principle of operation of the electromagnetic nozzle
Photo of the electromagnetic nozzle device
An electromagnetic device of this kind is usually used on gasoline engines, including those that have a direct injection system. This type of equipment is characterized by a rather simple design, which consists of a nozzle and a solenoid valve equipped with a needle.
The operation of the electromagnetic nozzle occurs in this way. The electronic control unit, in strict accordance with the previously laid down algorithm, provides voltage supply to the valve excitation winding at the required moment. In the process, an electromagnetic field is created that overcomes the force of the spring, then retracts the armature with the needle and thus releases the nozzle. This is followed by fuel injection. When the voltage disappears, the spring returns the nozzle needle to the seat.
The design and principle of operation of the electro-hydraulic nozzle
Photo of the device of the electro-hydraulic nozzle
Electro-hydraulic equipment of this kind is used on diesel engines, including those equipped with an injection system called "Common Rail". The design of this type of device combines a solenoid valve, drain and inlet throttles, and a control chamber.
The principle of operation of this equipment is based on the application of fuel pressure, both during injection and after its termination. The solenoid valve in the initial position is de-energized and completely closed, the needle of the device is pressed against the seat by pressure on the fuel piston in the control chamber. In this position, fuel injection is not carried out. It should be noted that in such a situation, the fuel pressure on the needle due to the difference in contact areas is less than the pressure exerted on the piston.
After the command of the electric control unit, the solenoid valve is activated and the drain throttle is opened. At the same time, the fuel in the control chamber flows into the drain line through the throttle. The intake throttle prevents rapid pressure equalization not only in the intake manifold, but also in the control chamber. Gradually, the pressure on the piston decreases, but the fuel pressure exerted on the needle does not change - as a result, the needle rises and, accordingly, fuel is injected.
Design, advantages and principle of operation of the piezoelectric injector
Scheme of the device of the piezoelectric nozzle
The most advanced device with which fuel injection is provided is piezoelectric equipment of this kind - it is called a "piezo injector". This type of device is installed on those diesel engines that are equipped with an injection system called Common Rail - a common rail fuel system.
The advantage of such devices is the rapid response (about four times faster than a solenoid valve), which results in the ability to repeatedly inject fuel during one cycle. In addition, the advantage of piezo injectors is the most accurate dosage of fuel that is injected.
The creation of this type of equipment became possible due to the use of the piezoelectric effect in the nozzle control, which is based on a change in the length of the piezocrystal as a result of voltage. The design of such a device includes a piezoelectric element and a pusher responsible for switching the valve, as well as a needle - all this is placed in the body of the device.
In the operation of this type of equipment, as well as in the operation of electro-hydraulic devices of this kind, the hydraulic principle is used. The needle in the initial position is seated on the seat due to the high fuel pressure. In the process of applying an electrical signal to the piezoelectric element, its length increases, which transfers force to the pusher piston. As a result of this, the switching valve opens and fuel enters the drain line. The pressure drops above the needle. Due to the pressure in the lower part, the needle is raised and, accordingly, fuel is injected.
The amount of fuel that is injected is determined by factors such as:
- duration of exposure to the piezoelectric element;
- fuel pressure at the fuel rail.
