Modification of the crankcase ventilation system of LADA engines (PCV valve)

April 20, 2017 Lada.Online 188 072 65

If, while operating a LADA car, you notice that during load (when the air conditioner is running, the heating is on, etc.) in a traffic jam, the engine begins to operate unstably (troits, pulls poorly, etc.), perhaps the reason lies in the ventilation system crankcase The article proposes to solve the problem by installing a PCV valve from a foreign car.

Diagram of the standard crankcase ventilation system

The crankcase ventilation system of VAZ engines consists of two circuits that operate at different load modes and speeds:

The small ventilation circuit is connected to the valve cover and the intake manifold (behind the throttle body). This connection diagram provides intensive crankcase ventilation due to the vacuum that occurs in the intake manifold when the throttle is closed. To avoid an effect such as hyperventilation, the cross-section of the small circuit is limited by a jet in the cable throttle body with a diameter of 1.7 millimeters. This circuit operates in the region of 800-1500 rpm.
A large ventilation circuit is connected to the valve cover and the air pipe (in the pre-throttle space). This scheme provides intensive crankcase ventilation at high speeds. The cross section of the large contour is 16-18 millimeters

Examples demonstrating the shortcomings of the standard crankcase ventilation system:

A car is going down a hill with the gear in gear. In this mode, the engine operates at higher speeds with a reduced load. A high vacuum is created in the crankcase, and a large ventilation circuit is connected, in which there are no control valves. Since both circuits are connected to one volume of the oil trap, a strong vacuum in the crankcase will draw a fresh portion of air bypassing the throttle. The mass air flow sensor will show increased air flow, and the ECU will try to close the throttle. Having realized that this is not possible (it is already closed), the lean mixture will be corrected by increasing the fuel supply (fuel consumption will increase). As a result, the entire internal volume of the engine will work as a parallel receiver of very significant volume, connected to the intake, bypassing the throttle. It is this volume that will interfere with the formation of a high-quality mixture.
A car in a traffic jam drives under tension with additional consumers (for example, the air conditioner is on). The compressor clutch is connected, the load increases abruptly. The engine does not have enough air, it begins to pull it from the crankcase, bypassing the throttle. But the ECU is also aware of the clutch engagement and also supplies more air by opening the throttle. The vacuum drops sharply, the vacuum brake booster (VBR) does not have enough strength to hold the car. Leap forward. The ECU sees an increase in oxygen and closes the throttle. A sharp increase in vacuum, VUT seizes. The car jerks, the transmission hits. And so on ad infinitum.

As a result, in both cases, when the engine is running, speed jumps occur and the engine choke under the load. Jerking and vibration are possible on manual transmissions, automatic transmissions and automatic transmissions. To eliminate these shortcomings, it is proposed to modify the design according to one of the presented schemes.

Improved crankcase ventilation. Useful improvements

It is worth noting the fact that modification of the crankcase ventilation allows us to solve some problems with excessive release of oil condensate and other problems with the functionality of the unit in question.
There may be several reasons for the accumulation of oil on the walls of the intake system of the power unit. The main contributing factors are related to the absence of a hydraulic intake, aimed at the unhindered flow of oil into the cylinder cavity according to the reverse flow pattern. In addition, the appearance of the presented malfunction is affected by a small number of in-line turns, which does not allow the emitted gases to gain the required speed. The design is able to filter out large particles of the product, but small components are ignored due to flaws in the base.

Schemes for upgrading the crankcase ventilation system

Schemes for modifying the crankcase ventilation system, as well as a description, are provided by IgorRV.

For LADA cars with manual transmission and AMT (“robot”), scheme No. 1 “Crankcase ventilation scheme with PCV valve for E-GAS and cable throttle” is suitable:

It is necessary to install a PCV valve (article 94580183, price about 400 rubles) from a foreign car into the small crankcase ventilation circuit. When connecting the PCV valve to a small circuit on an E-GAS, use a new hose (petrol-oil-resistant 8 mm without fabric reinforcement). On a cable choke, connect to the receiver, not to the choke.

As a result, the valve will shut off the circuits in transient modes, which will allow:

Accept the load without jerking or dropping engine speed (for example, when the compressor is running, heated windows, seats, etc.).
Reduce vibration load at idle
Increase traction from the bottom (noted by owners of automatic transmission with VAZ-21126 engine, manual transmission with VAZ-21227, 21126 and 11186 and AMT with VAZ-21127).
Get a sharper response to the gas pedal and faster shifts (on AMT). Perhaps due to the fact that the valve does not allow the engine to slow down, maintaining a more optimal switching algorithm.
Reduce oil consumption through ventilation.

The valve replacement period is 40,000 km.

For LADA cars with automatic transmission (Jatco) and AMT (“robot”), scheme No. 2 is suitable:

Description of scheme No. 2: The pressure reducing valve is connected in series to a large ventilation circle. Thus, it regulates the flow of crankcase gases at high speeds and during transient processes. This allows:

Exercise full control over the flow of crankcase gases between the small and large circuits.
Improve engine operating mode.
Reduce vibration load.
Reduce oil release into ventilation.

For LADA cars with automatic transmission (Jatco) and AMT (“robot”), scheme No. 3 is suitable:

Description of scheme No. 3: To improve the operation of the braking system and facilitate the process of holding the car on the brakes in mode “D”, an “Ejection Pump” was used. Due to the flow of crankcase gases from the small circuit, the vacuum in the tube leading to the vacuum booster increases. This happens at low speeds, which is very helpful when driving in traffic jams. Keeping your foot on the brake all the time is not very easy, but this pump makes the task easier.

Getting rid of vibrations, failures, transmission shocks.
The engine begins to operate more calmly and softly.
The force on the brake pedal becomes less.
The air conditioner turns on almost imperceptibly.

Required:

ejection pump (article 10793 VIKA, price 546 rubles);
pressure reducing valve (article 1117701500 JP GROUP, 422 rubles);
PCV valve (article 94580183 GENERAL MOTORS, 400 rubles);
clamps (about 10 pieces, 600 rubles);
thin, petrol-resistant 8 mm hose 50 cm (100 rubles);
standard ventilation pipe.

Installing the PCV valve on Granta

Installing the PCV valve on Vesta:

By the way, there are other ways to modify the crankcase ventilation system. Are you ready for such modernizations? Let us remind you that modification of the ignition system (installation of capacitor ignition coils in the harness) is also common among owners of LADA cars.

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Article: 2112-1014056, additional articles: 2112-1014056Р

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