How to check the adsorber

Many car owners may be interested in the question of whether how to check adsorber and its purge valve when the diagnostics showed its breakdown (an absorber error popped up). It is quite possible to perform such diagnostics in garage conditions, however, for this it will be necessary to dismantle either the adsorber completely or only its valve. And in order to carry out such a check, you will need locksmith tools, a multifunctional multimeter (to measure the insulation value and “continuity” of wires), a pump, as well as a 12 V power source (or similar battery).

What is an adsorber for?

Before moving on to the question of how to check the operation of the adsorber, let's briefly describe the operation of the gasoline vapor recovery system (called Evaporative Emission Control - EVAP in English). This will give a clearer picture of the functions of both the adsorber and its valve. So, as the name implies, the EVAP system is designed to capture gasoline vapors and prevent them from entering the unburned form into the surrounding air. Vapors are formed in the fuel tank when gasoline is heated (most often during prolonged parking under the scorching sun in the warm season) or when atmospheric pressure decreases (very rarely).

The task of the fuel vapor recovery system is to return these same vapors to the internal combustion engine intake manifold and burn them together with the air-fuel mixture. Usually, such a system is installed on all modern gasoline engines in accordance with the Euro-3 environmental standard (adopted in the European Union in 1999).

The EVAP system consists of the following elements:

• coal adsorber;
• adsorber purge solenoid valve;
• connecting pipelines.

there are also additional wiring harnesses going from the ICE electronic control unit (ECU) to the mentioned valve. With their help, control of this device is provided. As for the adsorber, it has three external connections:

• with a fuel tank (through this connection, the formed gasoline vapors enter the adsorber);
• with an intake manifold (it is used to purge the adsorber);
• with atmospheric air through the fuel filter or a separate valve at its inlet (provides the pressure drop that is needed to purge the adsorber).

Please note that on most vehicles, the EVAP system is only activated when the engine is warm (“hot”). That is, on a cold engine, as well as at its idle speed, the system is inactive.

An adsorber is a kind of barrel (or similar vessel) filled with ground coal, in which gasoline vapors are actually condensed, after which they are sent to the car's power system as a result of purging. Long and correct operation of the adsorber is possible only if it is regularly and adequately ventilated. Accordingly, checking the adsorber of a car is to check its integrity (since the body can rust) and the ability to condense gasoline vapors. also, old adsorbers pass the coal in them through their system, which clogs both the system and their purge valve.

Checking the adsorber valve with a multimeter

The adsorber purge solenoid valve performs exactly the purge of the system from the gasoline vapors present in it. This is done by opening it on command from the ECU, that is, the valve is an actuator. It is located in the pipeline between the adsorber and the intake manifold.

As for checking the adsorber valve, firstly, it checks the fact that it is not clogged with coal dust or other debris that can enter the fuel system when it is depressurized from the outside, as well as coal from the adsorber. And secondly, its performance is checked, that is, the possibility of opening and closing on command coming from the electronic control unit of the internal combustion engine. Moreover, not only the presence of the commands themselves is checked, but also their meaning, which is expressed in the time during which the valve must be opened or closed.

Interestingly, in ICEs equipped with a turbocharger, a vacuum is not created in the intake manifold. Therefore, for the system to work in it one two-way valve is also provided, triggered and directs fuel vapor to the intake manifold (if there is no boost pressure) or to the compressor inlet (if boost pressure is present).

Please note that the canister solenoid valve is controlled by the electronic unit based on a large amount of information from temperature sensors, mass air flow, crankshaft position and others. In fact, the algorithms according to which the corresponding programs are built are quite complex. It is important to know that the greater the air consumption of the internal combustion engine, the longer the duration of the control pulses from the computer to the valve and the stronger the purge of the adsorber.

That is, it is important not the voltage that is supplied to the valve (it is standard and equal to the total voltage in the machine electrical network), but its duration. There is such a thing as "adsorber purge duty cycle". It is scalar and is measured from 0% to 100%. The zero threshold indicates that there is no purge at all, respectively, 100% means that the adsorber is blown to the maximum at this point in time. However, in reality, this value is always somewhere in the middle and depends on the operating conditions of the car.

Also, the concept of duty cycle is interesting in that it can be measured using special diagnostic programs on a computer. An example of such software is Chevrolet Explorer or OpenDiag Mobile. The latter is perfect for checking the adsorber of domestic cars VAZ Priora, Kalina and other similar models. Please note that the mobile app requires an additional scanner, such as the ELM 327.

As a better alternative, you can buy an autoscanner Rokodil ScanX Pro. When using this device, you will not need any additional gadgets or software, which often requires additional paid extensions, for a specific make or model of car. Such a device makes it possible to read errors, monitor the operation of sensors in real time, keep trip statistics and much more. Works with CAN, J1850PWM, J1850VPW, ISO9141 protocols, so Rokodil ScanX Pro connects to almost any car with an OBD-2 connector.

External signs of damage

Before checking the adsorber purge valve, as well as the adsorber itself, it will certainly be useful to find out what external signs this fact is accompanied by. There are a number of indirect signs, which, however, can be caused by other reasons. However, when they are identified, it is also worth checking the operation of the EVAP system, as well as its constituent elements.

1. Unstable operation of the internal combustion engine at idle (the speed “floats” up to the point that the car starts and stalls, since it runs on a lean air-fuel mixture).
2. A slight increase in fuel consumption, especially when the internal combustion engine is running "hot", that is, in a warm state and / or in hot summer weather.
3. The internal combustion engine of a car is difficult to start “hot”, it is usually impossible to start it the first time. And at the same time, the starter and other elements related to the launch are in working condition.
4. When the engine is running at low speeds, there is a very noticeable loss of power. And at higher speeds, a decrease in the torque value is also felt.

In some cases, it is noted that if the normal operation of the gasoline vapor recovery system is disturbed, the smell of fuel can enter the passenger compartment. This is especially true when the front windows are open and / or when the car has been standing in a closed box or garage with poor ventilation for a long time. also, the depressurization of the fuel system, the appearance of small cracks in the fuel lines, plugs, and so on contribute to the poor performance of the system.

How to check the adsorber

Now let's move on to the algorithm for checking the adsorber (its other name is the fuel vapor accumulator). the basic task at the same time is to determine how tight its body is and whether it allows fuel vapors to pass into the atmosphere. So, the check must be performed according to the following algorithm:

Adsorber housing

• Disconnect the negative terminal from the vehicle battery.
• First, disconnect all hoses and contacts going to it from the adsorber, and then dismantle the fuel vapor accumulator. This procedure will look different for different machines, depending on the location of the node, as well as the mounting means with which it was fixed.
• you need to tightly plug (seal) two fittings. The first - going specifically to atmospheric air, the second - to the electromagnetic purge valve.
• After that, using a compressor or pump, apply a slight air pressure to the fitting going to the fuel tank. Don't overdo the pressure! A serviceable adsorber should not leak from the body, that is, be tight. If such leaks are found, then most likely the assembly needs to be replaced, since it is not always possible to repair it. namely, this is especially true if the adsorber is made of plastic.

it is also necessary to make a visual inspection of the adsorber. This is especially true of its hull, namely, pockets of rust on it. If they occur, then it is advisable to dismantle the adsorber, get rid of the mentioned foci and paint the body. Be sure to check for charcoal from the fumes accumulator leaking into the EVAP system lines. This can be done by examining the condition of the adsorber valve. If it contains the mentioned coal, then you need to change the foam separator in the adsorber. However, as practice shows, it is still better to replace the adsorber completely than to engage in amateur repairs that do not lead to success in the long term.

How to check the adsorber valve

If, after checking, it turned out that the adsorber is in a more or less operable state, then it is worth checking its solenoid purge valve. It is worth mentioning right away that for some machines, due to their design, some actions will be different, some of them will be present or absent, but in general, the verification logic will always remain the same. So, to check the adsorber valve, you need to do the following:

Adsorber valve

• Visually check the integrity of the rubber hoses included in the fuel vapor recovery system, namely, those that are suitable for the valve. They must be intact and ensure the tightness of the system.
• Disconnect the negative terminal from the battery. This is done to prevent false triggering of system diagnostics and to enter information about the corresponding errors into the electronic control unit.
• Remove the absorber (usually it is located on the right side of the internal combustion engine, in the area where the elements of the air system are installed, namely the air filter).
• Turn off the power supply to the valve itself. This is done by removing the electrical connector from it (the so-called "chips").
• Disconnect the air inlet and outlet hoses from the valve.
• Using a pump or a medical "pear", you need to try to blow air into the system through the valve (into the holes for the hoses). It is important to ensure the tightness of the air supply. To do this, you can use clamps or a dense rubber tube.
• If everything is in order with the valve, it will be closed and it will not be possible to blow air through. Otherwise, its mechanical part is out of order. You can try to restore it, but this is not always possible.
• it is necessary to apply electric current to the valve contacts from the power supply or battery using wires. At the moment the circuit is closed, you should hear a characteristic click, which indicates that the valve has worked and opened. If this did not happen, then perhaps instead of a mechanical breakdown, an electrical one takes place, namely, its electromagnetic coil burned out.
• With the valve connected to a source of electric current, you must try to blow air into it in the manner indicated above. If it is serviceable, and accordingly open, then this should work without problems. If it is not possible to pump through the air, then the valve is out of order.
• then you need to reset the power from the valve, and there will be a click again, indicating that the valve has closed. If this happens, then the valve is working.

also, the adsorber valve can be checked using a multifunctional multimeter, translated ohmmeter mode - a device for measuring the value of the insulation resistance of the electromagnetic winding of the valve. The probes of the device must be placed on the terminals of the coil (there are various design solutions where the wires coming from the electronic control unit are connected to it), and check the insulation resistance between them. For a normal, serviceable valve, this value should be approximately within 10 ... 30 Ohms or slightly differ from this range.

If the resistance value is small, then there is a breakdown of the electromagnetic coil (short turn-to-turn circuit). If the resistance value is very large (calculated in kilo- and even megaohms), then the electromagnetic coil breaks. In both cases, the coil, and hence the valve, will be unusable. If it is soldered into the body, then the only way out of the situation is to completely replace the valve with a new one.

Please note that some vehicles allow a high value of insulation resistance on the valve coil (namely, up to 10 kOhm). Check this information in the manual for your car.

so, in order to know how to check if the adsorber valve is working, you need to dismantle it and check it in garage conditions. The main thing is to know where its electrical contacts are, as well as to make a mechanical revision of the device.

How to repair adsorber and valve

It should be noted right away that both the adsorber and the valve in most cases cannot be repaired, respectively, they must be replaced with similar new units. However, with regard to the adsorber, in some cases, over time, foam rubber rots in its housing, due to which the coal in it clogs the pipelines and the EVAP system solenoid valve.

Rotting of foam rubber occurs for banal reasons - from old age, constant temperature changes, exposure to moisture. You can try to replace the foam separator of the adsorber. However, this can not be done with all units, some of them are non-separable.

If the adsorber body is rusted or rotten (usually also from old age, temperature changes, constant exposure to moisture), then you can try to restore it, but it’s better not to tempt fate and replace it with a new one.

Checking the valve with a homemade control

Similar reasoning is valid for the solenoid valve of the gasoline vapor recovery system. Most of these units are non-separable. That is, the electromagnetic coil is soldered into its housing, and if it fails (insulation breakdown or winding break), it will not be possible to replace it with a new one.

Exactly the same situation with the return spring. If it has weakened over time, then you can try to replace it with a new one, but this is not always possible to reproduce. But despite this, it is still better to make a detailed diagnosis of the adsorber and its valve in order to avoid expensive purchases and repairs.

Some car owners do not want to pay attention to the repair and restoration of the gas vapor recovery system, and simply "jam" it. However, this approach is not rational. Firstly, it really affects the environment, and this is especially noticeable in large metropolitan areas, which are already not distinguished by a clean environment. Secondly, if the EVAP system does not work correctly or does not function at all, then periodically pressured gasoline vapors will come out from under the gas tank cap. And this will happen as much more often, how high the temperature will be in the volume of the gas tank. This situation is dangerous for several reasons.

Firstly, the tightness of the tank cap is broken, in which the seal is broken over time, and the car owner will probably have to periodically buy a new cap. Secondly, gasoline vapors not only have an unpleasant odor, but are also harmful to the human body. And this is dangerous, provided that the machine is in a closed room with poor ventilation. And thirdly, fuel vapors are simply explosive, and if they leave the gas tank at a time when there is a source of open fire next to the car, then a fire situation appears with very sad consequences. Therefore, it is not necessary to "jam" the fuel vapor recovery system, instead it is better to keep it in working order and monitor the canister and its valve.

Hack and predictor Aviator

Checking the adsorber, as well as its electromagnetic purge valve, is not very difficult even for novice car owners. The main thing is to know where these nodes are located in a particular car, as well as how they are connected. As practice shows, if one or the other node fails, they cannot be repaired, so they need to be replaced with new ones.

As for the opinion that the fuel vapor recovery system must be turned off, it can be attributed to misconceptions. The EVAP system must work properly, and provide not only environmental friendliness, but also the safe operation of the car in various conditions.