Variable Valve Timing (VVT) – Benefits & Advantages Explained

08/26/2023 Timing
Variable Valve Timing - Benefits & Advantages Explained
Variable Valve Timing - Benefits & Advantages Explained

Variable valve timing (VVT) systems, do exactly what they say, they vary the valve timing.

Today, drivers want, a different reaction from the engine, through various RPMs.

For example, at high RPMs, the driver may desire more power.  However, fuel economy may be the priority, at low RPMs with lighter engine loads.

Variable valve timing (VVT), enables your engine, to react to these varied speeds. Consequently, by changing how the intake and exhaust valves work, at different engine speeds. As a result, it helps optimize the engine’s performance, while also improving fuel economy and emissions.

Variable valve timing (VVT) technology controls, three key characteristics, of the intake and exhaust valves:

  • Valve timing, the points in the piston’s movement, at which the valves open and close.
  • Valve duration, how long the valves stay open.
  • Actual valve lift, how much the valves physically open (their opening aperture).

So, maximum overlap is needed, between intake and exhaust valves’ opening, whenever the engine is running at high speed.

Variable Valve Timing (VVT)
Variable Valve Timing (VVT)

However, when the vehicle is running at medium highway speed, in other words, the engine is running at light load. Maximum overlapping may be useful, as a means to reduce fuel consumption and emissions.

Firstly the exhaust valves, do not close until the intake valves have been open for a while. So, some of the exhaust gases, are recirculated back into the cylinder. Furthermore, at the same time as, the new air/fuel mix enters. Because, part of the air/fuel mix, is replaced by exhaust gases, less fuel is needed.

So, the exhaust gas is mostly, non-combustible gas, such as CO2. Then, the engine runs properly, at the leaner air/fuel mixture, without failing to combust.

But, As Great As Variable Valve Timing Is, It Is Also Vulnerable To Some Problems.

On (VVT) systems, oil pressure is used to actuate the cam phaser. So, oil quality, viscosity and contamination problems, can affect the operation of the phaser.

So, if the phaser does not receive:

  • Adequate oil pressure.
  • The oil is the wrong viscosity (too thick or too thin).
  • The oil is dirty.

It may prevent the phaser from working properly.

Oil Flow Control Solenoid
Oil Flow Control Solenoid

As a result, hurting engine performance, fuel economy and emissions. Furthermore, such faults will often, turn on the Check Engine light and set a (VVT)-related fault code.

Variable Valve Timing (VVT) Generic OBD-II Fault Codes:

  • P0010….A Camshaft Position Actuator Circuit Bank 1
  • P0011….A Camshaft Position Timing Over-advanced or System Fault Bank 1
  • P0012….A Camshaft Position Timing Over-retarded Bank 1
  • P0013….B Camshaft Position Actuator Circuit Bank 1
  • P0014….B Camshaft Position Timing Over-Advanced or System Fault Bank 1
  • P0015….B Camshaft Position Timing Over-Retarded Bank 1
  • P0020….A Camshaft Position Actuator Circuit Bank 2
  • P0021….A Camshaft Position Timing Over-Advanced or System Fault Bank 2
  • P0022….A Camshaft Position Timing Over-Retarded Bank 2
  • P0023….B Camshaft Position Actuator Circuit Bank 2
  • P0024….B Camshaft Position Timing Over-Advanced or System Fault Bank 2
  • P0025….B Camshaft Position Timing Over-Retarded Bank 2

How Do I Reset The “Check Engine Or Service Engine Soon” Light?

After you’ve properly diagnosed and fixed the problem that triggered the OBD trouble code. You can reset or clear the Check Engine, a number of different ways:

  • You can just drive it and after a certain number of driving cycles, it will just clear by itself.
  • Disconnect your battery, turn on the headlight switch for about five to ten minutes, and reconnect the battery. But, will likely result in, you losing your radio presets and perhaps, some other small things like that.
  • Most, if not all scan tools, have an option to clear or reset codes. Without the use, of any tools or touching the battery.

Back in the day:

  • The engines intake and exhaust valves, opened a specific amount.
  • At a specific point, in the four stroke cycle.
  • Also, for a specific amount of time.

But, nowadays many engines can change, when their valves open, how much they open and for how long.

(VVT) Variable Valve Timing - Improves Low And High Speed Torque
(VVT) Variable Valve Timing – Improves Low And High Speed Torque

Conclusion

So, these systems are complex. And, it’s essential that you change your engine oil, at the recommended intervals. Also, make sure you are using, the correct weight and viscosity, that’s in your manufacturer’s recommendations. Above all, the solenoids that control (VVT) systems, can easily fail, by improper lubrication.

Thank You !

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