VVTI is a system developed by Toyota for variable valve timing. If you translate this abbreviation from English, then this system is responsible for the intellectual phase shift. Now the second generation of mechanisms is installed on modern Japanese engines. And for the first time VVTI began to be installed on cars since 1996. The system is a coupling and a special VVTI valve. The latter acts as a sensor.
The valve device of the VVTI system of Toyota cars
The element consists of a housing. In the outer part there is a control solenoid. He is responsible for the movement of the valve. The device also has o-rings and a connector for connecting the sensor.
General principle of the system
The main control device in this valve timing system is the VVTI coupling. By default, engine designers designed valve opening phases to get good traction at low engine speeds. As the speed rises, so does the oil pressure, which opens the VVTI valve. Toyota Camry and its 2.4-liter engine works on the same principle.
After this valve opens, the camshaft will turn to a certain position relative to the pulley. The cams on the shaft have a special shape, and during the rotation of the element, the intake valves will open a little earlier. Accordingly, later to close. This should have the best effect on engine power and torque at high speeds.
Detailed job description
The main control mechanism of the system (and this is the coupling) is installed on the camshaft pulley. Its body is connected to a star or gear pulley. The rotor is connected directly to the camshaft. Oil from the lubrication system is supplied from one or both sides to each rotor blade on the coupling, causing the camshaft to rotate. When the engine is not started, the system automatically sets the maximum delay angles. They correspond to the latest opening and closing of the intake valves. When the engine starts, the oil pressure is not strong enough to open the VVTI valve. To avoid any shock in the system, the rotor is connected to the clutch housing with a pin, which will be squeezed out by the oil itself with increasing lubricant pressure.
System operation is controlled by a special valve. According to the signal from the computer, the electric magnet with the help of a plunger will begin to move the spool, thereby passing oil in one or the other direction. When the motor is stopped, this spool moves due to the spring so as to set the maximum angle of delay. To rotate the camshaft at a certain angle, oil under high pressure through the spool is fed to one of the sides of the petals on the rotor. At the same time, a special cavity opens onto the drain. It is located on the other side of the petal. After the ECU understands that the camshaft is rotated to the desired angle, the pulley channels overlap and it will be further held in this position.
Common Symptoms of VVTI System Problems
So, the system should change the phases of the gas distribution mechanism. If there are any problems with it, then the car will not be able to function normally in one or several operating modes. There are several symptoms that will indicate malfunctions.
So, the car does not keep idle at the same level. This indicates that the VVTI valve is not working as it should. Also about various malfunctions in the system will say "braking" of the engine. Often, with problems with this mechanism of phase change, the motor cannot run at low speeds. Error P1349 may also indicate problems with the valve. If the engine is warm at high idle, the car does not go at all.
Possible causes of valve malfunction
The main causes of valve malfunctions are not so many. Two can be distinguished, which are especially common. So, the VVTI-valve may fail due to the fact that there are breaks in the coil. In this case, the element will not be able to respond correctly to voltage transmission. Diagnosing a malfunction is easily done by checking the measurement of the resistance of the coil of the sensor coil.
The second reason that the VVTI (Toyota) valve is malfunctioning or does not work at all is jamming in the stock. The reason for such jamming may be commonplace dirt, which eventually accumulated in the channel. It is also possible that the sealing gum inside the valve is deformed. In this case, it is very simple to restore the mechanism - it is enough to clean the dirt from there. This can be done by soaking or soaking the element in special fluids.
How to clean the valve?
Many problems can be cured by cleaning the sensor. First you need to find the VVTI valve. Where this element is located can be seen in the photo below. He is circled in the picture.
To remove the sensor, remove the plastic cover of the power unit. Then remove the metal cover, which fixes the generator. The valve will be visible under the cover. It is necessary to disconnect the electrical connector from it and unscrew the bolt. It is very difficult to make a mistake here - this is the only bolt here. Then the VVTI 1NZ valve can be removed. But for this you do not need to pull the connector. It is very tight to the sensor. Also, a rubber o-ring is installed on it .
Cleaning can be done with carburetor cleaning fluids. To completely clean the system, remove the filter. This element is located under the valve - it is a plug in which there is a hole for the hexagon. The filter also needs to be cleaned with this fluid. After all operations, it remains only to assemble everything in the reverse order, and then install the generator belt, without resting on the valve itself.
How to check VVTI valve?
Checking if the valve is working is very simple. To do this, a voltage of 12 V is supplied to the sensor contacts. It must be remembered that it is impossible to keep the element energized for a long time, since it cannot work in such modes for so long. When voltage is applied, the rod will retract inward. And when the circuit opens, he will come back.
If the stem moves easily, the valve is fully operational. It only needs to be washed, lubricated and can be operated. If it does not work as it should, then repair or replacing the VVTI valve will help.
Self repair valve
First dismantle the regulator bar of the generator. Then remove the hood lock fasteners. This will allow access to the axial bolt of the generator. Next, unscrew the bolt that holds the valve itself, and remove it. After they remove the filter. If the last element and valve are dirty, then these parts are cleaned. Repair is a check and lubrication. You can also replace the o-ring. More serious repairs are not possible. If the part does not work, it is easier and cheaper to replace it with a new one.
Independent VVTI Valve Replacement
Often cleaning and lubrication does not provide the desired result, and then the question arises of the complete replacement of the part. In addition, many car owners after the replacement claim that the car began to work much better and reduced fuel consumption.
First, remove the regulator bar of the generator. Then remove the hood lock fasteners and gain access to the generator bolt. Open the bolt that holds the desired valve. The old element can be pulled out and thrown away, and a new one is put in place of the old. Then tighten the bolt, and the car can be operated.
Conclusion
Modern cars are both good and bad. They are bad in that not every operation related to repair and maintenance can be performed independently. But replacing this valve with your own hands can be done, and this is a big plus for the Japanese manufacturer.