What Does CVVT Stand for in Cars & Symptoms of a Bad Variable Valve Timing VVT ?

Posted by Candy Lai on

Why is CVVT engine better than VVT?
Who makes the CVVT transmissions?
How to order Hyundai CVVT?
What does VVT stand for in cars?
Where to find CVVT meaning?
When Hyundai breakthrough CVVT problems?
What different from CVVT and CVT?
How can I resolve these problems about CVVT engine?

What is CVVT (Continuously Variable Valve Timing) System

The CVVT is Hyundai named for his VVT, same as Kia cvvt engine, positioned at hyundai sonata exhaust camshaft, controls the open & close timing of intake valve to improve engine performance.

Different car manufacturer has different name to differentiate their own variable valve timing, for example, VVT-i is the name Toyota use while Honda uses V-Tec.

This unprecedented design changed the way to control the intake & exhaust valves open and closing timing with hydraulic.

It was found that engine was starving for higher volume air-fuel mixture as the intake valve opening time reduced at high speed.
Also the exhaust gases were lack of time to fully expel at higher RPMS.


CVVT engine system adjusts the intake valve timing longer at higher rpm.
With the advanced intake valve and longer delayed exhaust, it allows more air entering the engine at higher rpm.
It delivers optimum air-fuel mixture fully filled the combustion chamber and the oil efficiency improves.

This just reminds me of my swimming training memory.

I always feel daunting when I can’t breathe well and struggle for more air when I tend to swim faster.

I really wished I could have the Olympian Flying Fish Phelps lung so I can feel easier to breathe in the pool.  

Yes, VVT system is like using Phelps lung equipped onto a normal human, to let engine chamber can “BREATHE” easier at higher RPMS.

You can imagine if now we download an extension app on the Phelps lung to monitor the lung’s actions. , to let it act more sensitive

Do you think will the lung works even better?

Does it remind you of any parts related to the VVT?



That’s the VVT solenoid!
variable valve timing solenoid

You can refer to our before article to get more information to maintain your variable valve timing solenoid, What Cause a Falling Variable Valve Timing VVT Solenoid & How to Fix Bad Oil Control Valve?


Benefits of camshaft gear CVVT

More and more new vehicles likes VVT design as it brings significant benefits.

  1. Fuel Consumption Reduction
    With VVT overlapping time adjustment of intake & exhaust valves, more air can get into engine in time. So it reduces fuel consumption and improves oil efficiency.

  2.  Emission reduction for environment friendly.
    VVt design has efficiently reduced NOX emission by EGR effect since 2007.
    Also the CO & CO2 emission also reduced due to full combustion.

  3. Torque increased at low speed so car performance improved

  4. Overall, the power distribution is better across different RPM range.


Symptoms of a Bad or Failing Variable Valve Timing (VVT)
1. Poor Fuel Economy Performance
If the CVVT has malfunction, it will fail to control the valves open and close at precise time to optimize the fuel performance and reduce the emission.

This will cause fuel consumption dramatically increased.
If you sense the fuel performance is poor than before, contact your mechanic to check your vehicle, both VVT and solenoids.

2. Check Engine Light On
Whatever the electrical component is failing, the vehicle’s ECU will activate the

Check Engine Light to alert us.

So when VVT is sending inaccurate data to ECU, ECL will be on and it is telling us to diagnose the potential problems.

3. Engine Rough Idle
VVT adjusted the intake & exhaust valves open & close timing according to the engine RPM.

If the VVT is failing, the adjustment function will be compromised.

Too much oil will flow into VVT gears and cause engine idle rough. 

The circumstance is significant obvious during the RPM is at 100 to 300.

 4. Poor Acceleration

The faulty VVT will fail to inform engine for the instant acceleration.

You will feel poor acceleration and sometimes the engine misfire appers.


Just as we mentioned before, the CVVT system is driven with hydraulic theory so the clean engine oil and correct viscosity is crucial.
The clogged oil with debris will cause the VVT malfunction very easily.

The passageway from solenoid to CVVT chain & gears will be clogged up.

And Similar to Kia Optima exhaust, Hyundai Santa Fe Variable Valve Timing (VVT) Replacement costs around $157 to $380 depends on serious level.
Any above symptoms occurs, better visit the auto service center to check your car first. 

Earlier you sort out the problems, cheaper cost you may need to spend. 

And make sure you check the oil level regularly and change the engine oil according to car manufacturer manual to avoid above situation.



Read More:

<hyundai Parts sonata engine parts>


How Important is Timing Chain Replacement & When do You Change a Timing Chain

<4 Symptoms of a bad transmission linear solenoid>

<Common reasons cause variable valve timing problems in your car>


<Ways to longer Camshaft Variable Valve Timing VVT gear lifetime>


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