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...
Are Toyota VVT-i motors reliable?
The creation of TokyoTOYOTA MOTOR CORPORATION’s new “Variable Valve Timing-intelligent” (VVT-i) technology, which improves performance and fuel efficiency, was unveiled today.
Modern engine development must focus on both improved fuel efficiency and improved vehicle performance. The societal needs of protecting the environment and natural resources must also be met by modern engines.
Toyota added the WT mechanism to their 4A-GE sports engines in 1991 in an effort to boost engine production and torque. Depending on the state of the engine, WT permits the intake valve to open and close in two phases.
An enhanced version of the WT mechanism is called VVT-i. In order to deliver the best valve timing dependent on driving conditions, VVT-i continually modifies the open/close time of the intake valve. The benefits of VVT-i include improved fuel efficiency, higher torque and output, and decreased nitrogen oxide (NOx) and hydrocarbon emissions.
The VVT-straightforward i’s architecture makes it incredibly dependable and simple to adapt for already-existing engine designs. The new technology is anticipated to have numerous uses in the future.
A new model that will be released within the year will be the first to integrate VVT-i engines. Tests have shown that VVT-i boosts low and medium range torque by roughly 10% while increasing fuel economy by about 6%.
What accomplishes a VVT-i engine?
With variable valve timing, less air-fuel combination enters the engine during light acceleration or idle, resulting in a reduction in emissions. Because the valves are open for a longer period of time during heavy acceleration, the engine receives more air-fuel mixture, which boosts power.
With Toyota’s VVT-i, the “brain that regulates engine operations,” the electronic control unit, continuously determines the ideal time to open and close the valves and activates an oil pressure valve to vary the timing by changing camshaft speed.
Some Toyota engines, including the 3.5-liter V-6 in the Highlander SUV, use electric motors to adjust the intake valve timing. Toyota refers to these engines as VVT-iE engines (for Electric). The exhaust valves of engines like the 3.5-liter and 2.5-liter used in the Camry sedan also have variable timing, and they are referred to as Dual VVT-i. Toyota claims that VVT-i increases power, enhances fuel efficiency, and lowers pollutants by adjusting valve timing based on driving conditions.
Variable timing was originally made available by Alfa Romeo in 1980. Other automakers soon followed, including Honda in 1989 with its VTEC technology. VVT-i was first announced by Toyota in 1995 and debuted in the United States in the 1998 Lexus LS 400. The first Toyota model having it in the United States was the Celica, model year 2000.
All of the current Toyota vehicles sold in the US have VVT-i engines, with the exception of the 86 coupe, Supra sports car, and Mirai fuel-cell vehicle. Both the 86 and the Supra have variable valve timing and use Subaru or BMW engines, respectively.
How durable is the Toyota VVT-i 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?
Does oil burn in VVT-i engines?
I’m not sure if this belongs in Technical, but because it has an impact on many models, I thought I’d share it here. HJ has updated the automobile review area briefly, but I decided to go into more detail here for everyone’s benefit.
To put it simply, any Toyota VVT-I 1.4, 1.6, and 1.8L engines (1zz 1.8, 3zz 1.6, and 4zz 1.4) produced between 2000 and mid-2005 may experience high oil consumption of 1L/600miles. I don’t believe the smaller 1.0 and 1.3 engines, the 2.0, or the larger VVTI engines had this issue.
Insufficient oil capacity and inadequate piston and piston ring design were the root causes. Due to the oil-ways sludging up as a result, the rings’ surrounding hardened oil eventually caused the bores to misalign.
Since extending the warranty on these engines to six years, Toyota might retrofit these to older Toyotas built before around July 2005.
New Toyota vehicles built after around July 2005 have this patch installed, thus they should not experience this problem.
1. Buy a Toyota built after July 2005 with a VVT-I engine, with the exception of select Corollas that have the fix since September 2005. Therefore, obtain the VIN and contact Toyota UK.
2. If purchasing an older model, contact Toyota UK to see if the patch has already been implemented because the warranty will no longer be valid.
Vott-i saves fuel, right?
VVT and related lift technologies aid in enhancing combustion. This results in improved engine performance, decreased emissions, and a 16% decrease in fuel consumption.
VVT-i versus non-VVT-i: Which is better?
The vvti’s main advantages thus far are that it produces more torque at a lower rpm than the non-vvti, that it is a newer engine with less wear, and that it already has a single turbo.
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.
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.
Are VVT and VTEC the same thing?
Honda created the VTEC (Variable Valve Timing & Lift Electronic Control) technology to increase a four-stroke internal combustion engine’s volumetric efficiency, which leads to better performance at high RPM and less fuel usage at low RPM. The VTEC system alternates between two (or three) camshaft profiles using hydraulic pressure. Ikuo Kajitani, a Honda engineer, created it. [1][2] It differs significantly from conventional VVT (variable valve timing) systems, which just alter the valve timings and make no adjustments to the camshaft profile or valve lift.
Which automobiles have 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.
- There are two sets of cam lobes that are used and exchanged as necessary.
- 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: