Techniquest Glyndr’s ZR engine with intelligent variable valve timing, shown in a cutaway view.
Toyota created the variable valve timing technology known as VVT-i, or variable valve timing with intelligence, for use in automobiles. The Toyota VVT-i system takes the place of the Toyota VVT, which was available on the 4A-GE engine’s 5-valve per cylinder starting in 1991. The VVT system is a two-stage cam phasing mechanism that is hydraulically regulated.
VVT-i, which debuted on the 2JZ-GE engine in 1995 for the JZS155 Toyota Crown and Crown Majesta, modifies the interaction between the intake camshaft and camshaft drive (a belt or chain). An actuator is subjected to engine oil pressure in order to change the camshaft position. Improved engine efficiency is achieved by adjusting the overlap time between the exhaust valve shutting and intake valve opening[1]. Subsequently, different iterations of the system, such as VVTL-i, Dual VVT-i, VVT-iE, VVT-iW, and Valvematic, have been developed.
In This Article...
How reliable are Toyota Dual VVT-i engines?
Dual VVT-i technology from Toyota improves system performance and helps to further reduce emissions by adjusting both the intake and exhaust valves. More power, better responsiveness, better mileage, and lower pollutants are the practical results for the driver.
What occurs when VVT malfunctions?
The valve timing may not advance or retard as required if the VVT solenoid isn’t working properly. The engine may consequently display performance issues, such as jerky running and slow acceleration.
How durable is the Toyota VVT engine?
Everyone is aware that Toyota manufactures indestructible engines, but like the majority of man-made objects, there are production problems and prospective weaknesses to watch out for. This article will go over the Toyota 4.0 V6’s dependability in detail and the highest mpg you can get out of the v6 monster.
The 2009 and later vehicles’ Dual VVT-i 4.0 V6 engine is quiet, dependable, and smooth, with an engine life that easily exceeds 200,000 miles (320,000 km).
It goes without saying that the secret to an engine’s dependability is routine maintenance and the use of premium oils and lubricants. Undoubtedly, certain engines are more likely than others to experience mechanical and dependability problems.
So how does the 4.0 v6 fare in terms of durability and dependability? What are some of the potential problems you can anticipate and how effective are these engines really?
How can I tell whether my VVT is functioning?
The engine will also misfire or appear to stumble if your VVT switch is malfunctioning while your car is carrying extra weight, going up hills, or when you press hard on the accelerator to accelerate quickly. This is frequently brought on by a switch’s electrical malfunction rather than always by the switch itself. It’s likely that the variable valve timing switch won’t need to be replaced if you identify this issue and call a nearby ASE-certified repair to evaluate the situation. However, a correct diagnosis is required to confirm that it is an external issue. The likelihood of future engine damage will rise if you ignore the issue.
Regardless of the exact cause, you should always be proactive and get in touch with a qualified mechanic as soon as you observe any of the aforementioned warning signs or symptoms. The possibility that a problem can be fixed without resulting in further harm to other engine components greatly improves if you identify it as soon as the symptoms appear. As soon as you see any of these symptoms, call a local YourMechanic experienced mechanic.
What makes VVT and VVT-i different from one another?
VVT-i is a smart application of the VVT technology that I previously described, employing microprocessors to control the VVT functionality through a few actuators. Toyota created VVT-i, which began using it in 1996 and brought changes to the timing of the intake and exhaust valves. The Toyota VVT technology, which was introduced in 1991 for 4A-GE engines, was intended to be replaced with this variable valve timing technology for automobiles, which is somewhat comparable to BMW’s VANOS.
By adjusting the mechanisms between the camshaft drive (belt, chain, etc.) and the intake camshaft, the technology is to blame for differences in the timing of the intake valves. The engine oil pressure that is applied to the actuator to change the camshaft position serves as the adjustment’s medium. Higher engine efficiency is the result of adjustments made to the gap duration between the opening of the intake valve and the shutting of the exhaust valve. Since the release of VVT-i, a number of variations of this system have been developed, including VVTTL-i, Dual VVT-i, VVT-iE, and Valvematic.
What vehicles feature VVT engines?
A type of piston engine technology known as variable valve timing, or VVT, purposefully offers irregular timing of the intake and/or exhaust valves. This helps an engine offer top performance under a variety of driving circumstances and improves gas mileage. Traditional piston engines, for instance, frequently need to trade off low-end torque for high-end power (or vice versa). Both of these ideal performance parameters are easier to fulfill with a VVT engine.
Variable Valve Timing – How it Works
Similar to conventional piston engines, VVT engines drive the air flow through the intake and exhaust valves via cams on a camshaft. The amount of air injected into the engine during each cycle directly depends on the timing of this valve lift. A typical piston engine frequently does not allow enough air to flow during each cycle, resulting in reduced output performance at times when the engine needs greater air flow (for example, high speeds or acceleration). On the other hand, a conventional piston engine with longer exhaust and intake cycles will have lower fuel economy at slower speeds.
In order to shorten exhaust and intake cycles at high speeds and lengthen them at slow speeds, a number of specialized VVT engine technologies are used. The following are the three main ways to change an engine’s valve timing:
- When necessary, the intake or exhaust valves’ real timing is slowed down or sped up.
- For best effectiveness, timing and lift are continuously changed (called continuous variable valve timing)
- There are two sets of cam lobes that are used and exchanged as necessary.
History of Variable Valve Timing (VTT)
Initially employed to power steam engines in the 19th century, variable valve timing. The first variable valve timing system for use in automobiles was patented by Fiat in the late 1960s. A pioneering device was also patented by GM in 1975, but it was abandoned because of lift issues. A vehicle utilizing VVT technology wasn’t made accessible for the North American market until 1980. With the release of the 1980 Alfa Romeo Spider, this was accomplished. In the 1980s and 1990s, other automakers introduced VVT engines of their own, following suit. The Honda VTEC technology was introduced in 1989, and the Nissan NVCS (Nissan Valve-Timing Control System) was introduced in 1986.
The EPA and other government agencies are putting more pressure on automakers to increase fuel efficiency, so this is a serious worry. To comply with more stringent guidelines for car emissions and efficiency, many of them are now using VVT technology.
Proprietary Terms for VVT
While some automakers simply refer to such engines as having “variable valve timing” or “VVT,” many use proprietary technology and as a result add a proprietary word to set their engines apart from the competitors. The terminology each automaker uses to identify an engine using VVT technology are listed below:
How is a poor VVT diagnosed?
Almost all individual components are monitored by the engine control unit (ECU), which controls modern cars nowadays. The ECU will record a specific issue code when a component starts to fail, alerting a mechanic using a scan tool that a problem is present. Once the code has been produced, it will alert the driver by turning on a warning light for a certain zone. The Check Engine Light is the most frequent light to come on when a VVT solenoid fails.
Every automotive manufacturer has a different set of codes, so it’s important for a car owner to get in touch with a nearby ASE Certified technician who will inspect the vehicle, download the code using the proper diagnostic equipment, and identify the precise cause of the issue. For any automobile manufacturer, there are literally dozens of different codes for VVT solenoid problems. The mechanic can start resolving the specific problem after they have this first information.
How much does a VVT solenoid replacement cost?
There are many factors to take into account before changing this component. For starters, it’s possible to change the VVT solenoid and the oil control valve (OCV) simultaneously. This is due to the fact that when this part malfunctions, both pieces typically require replacement.
There is no defined cost for either element when replacing just one component. This is due to the fact that costs vary depending on the engine being repaired and the parts that may be found nearby. Depending on whether a new oil control valve is required, the cost to repair a faulty variable valve timing solenoid can range from $325 to over $700 on average.
However, the average price ranges from $400 to $1,300 when all the parts are replaced at once.
Depending on the make and model of the car, the price range for replacing both parts is between $400 and $700. According to customers, replacing these parts with OEM (original equipment manufacturer) parts cost them up to $800. When customers used non-OEM brands or aftermarket replacement parts, the average cost was about $550.
Do VVT engines work well?
Benefits of VVT Using VVT has a lot of advantages and almost no disadvantages. One advantage is a 25% increase in maximum engine speed, which results in more peak power. Additionally, low speed torque is boosted, improving driving dynamics. You might believe that having an overlap between the intake and exhaust valves is unproductive because it signifies that exhaust gases are reentering the cylinder. Exhaust gas recirculation (EGR), on the other hand, is a crucial component of emission control and can be improved with VVT. The engine becomes more efficient when operated at medium speeds with a light engine load, such as when traveling on a highway, where maximum overlap typically occurs. The exhaust gas recirculation lowers the quantity of fuel required to power the engine, increasing the crucial MPG figure.
The extra expense and complexity of installing VVT in an engine is the sole negligible disadvantage. There are various approaches of adding VVT, and each manufacturer has a unique modificationsome are easier and less expensive to implement than othersthat they use. Regardless of design, improved fuel economy and power output are more advantageous in the long run than any up-front costs, especially when considering the multi-year investment in an automobile.
Does the typical motorist understand anything from all of this fancy talk? Most likely not, but it might offer you a question to put to the salespeople the next time you’re looking for a car. Fans of racing and high-performance vehicles will undoubtedly be curious to learn how various VVT technology might impact the output of their engines. One thing is certain: manufacturers will continue to come up with innovative and affordable ways to incorporate VVT into regular cars as the requirements for fuel efficiency are further mandated.
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VTEC vs Turbo: Which is superior?
While VTEC is more focused on extracting the maximum amount of horsepower from the engine because torque on VTEC cars can only be felt on the VTEC range, which is anyplace after 5,500RPMs, the torque produced by a turbo is still negligible in comparison.