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. Engine efficiency is increased by adjusting the gap between the opening of the intake valve and the shutting of the exhaust valve. [1] Subsequent variations of the system include included VVTL-i, Dual VVT-i, VVT-iE, VVT-iW, and Valvematic.
In This Article...
What makes VVT different from non-VVT?
A front timing cover with a bulge and an additional electrical hookup is a sign of an engine with VVT. Gen IV vehicles without VVT have a flat front cover.
What makes VVT and VVT-i different from one another?
The functionality of a system called VVTL-i was derived from VVT-i, but it differs in that it modifies both the valve timing and the valve lift (duration).
Dual VVT-i, as its name suggests, would perform the same task simultaneously on two valves. In 1998, 3S-GE engines were given the option of dual VVT-i, which modifies both the intake and exhaust valve camshaft timing.
Variable valve timing intelligent by electric motor is referred to as VVT-iE. This technology, a Dual VVT-i variation, uses an electrically powered actuator to alter and maintain the intake camshaft timing.
Honda also created a proprietary technique known as VTEC (Variable Valve Timing and Lift Electronic Control), which not only changed the timing of the camshafts but also allowed an engine to have numerous camshafts, improving performance.
VTEC engines have an additional intake cam with its own rocker that comes after the main cam and opens the valve for a longer time.
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.
Do VVT engines work well?
advantages of VVT Utilizing VVT has a lot of advantages and hardly any 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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Can VVT be disabled?
likewise turn off the vvt code. The vvt spark tables can be zeroed out if you’d like. The vvt cam tables themselves do not need to be zeroed out because doing so nullifies them already. The most despised gain the most influence.
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:
- There are two sets of cam lobes that are used and exchanged as necessary.
- 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)
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:
When does VVT start working?
Over the full rev band, the change is present. All DOHC engines are typically peak RPM engines that require revving to provide power. The VVT adjusts the timing to help shift the engine’s power curve downward and keep it there so that it produces maximum power and torque at lower RPM.
Better power feel, MPG, and emissions will all increase by lowering the engine’s torque.
Now that the engine has a turbo with VVT and DI, you may push things even further such that the engine’s maximum torque is realized between 1800 and 5200 RPM. The torque curve is a flat plain rather than a curve.
At slightly over 1800 RPM, my HHR SS Turbo reaches 315 FT LBS and can maintain it until around 5300 RPM. It is incredible how it alters the way the engine feels. Additionally, even with the 45 HP increase, the MPG increased by 1-2 MPG when I increased the weight from 235 FT LBs to 315 FT LBs. This was accomplished with the GM Performance Turbo Upgrade, and a GM drive line engineer verified the gain in MPG. Although surprising, he claimed that they would accept it. According to him, a DI engine uses less the more you let off the throttle because the low end torque helps the car accelerate more quickly.
Be aware that DI engines will turn off the gasoline to the engine when coasting in gear while out of gas.
Is the Toyota VVT-i engine dependable?
Toyota makes it. Any Toyota already has a well-deserved reputation for being the absolute best in terms of dependability and toughness. It would be nitpicking to try to differentiate between these two variations, which are nearly identical. If you perform regular maintenance, a timing belt problem won’t arise.
You might also argue that because older vehicles often have more miles on them and are statistically more prone to fail.
The Land Cruisers are not the only vehicles with the VVTi system. It is present throughout the whole Toyota lineup and has established its value reliability in terms of power and fuel efficiency.
Consider the benefits: more overall power and efficiency. That shouldn’t be taken seriously for a large vehicle like the Land Cruiser. especially once you add armor, accessories, higher tires, and possibly a tow.