How to check injection nozzles without removing from the engine

24.03.2021

Fuel system

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 motor;

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 diagnostic technique 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.