The (VVT) Variable Valve Timing that most of us see in our shops is actually variable “camshaft” timing.

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

Also, Variable valve timing allows valve timing to change with engine (RPM), unlike standard fixed cam drives that never change. Valve timing determines when the intake and exhaust valves open, how long they remain open, and when they close. As a result, this affects intake and exhaust flow, intake manifold vacuum, running compression, volumetric efficiency, throttle response, and horsepower.

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(VVT-i) – Variable Valve Timing – How Does It Work

Variable valve timing-cam phasing-VVT- how does it work

Variable valve timings (VVT) Generic OBD II Fault Codes

So, Most modern (VVT) systems utilize engine oil pressure and some type of an electronic solenoid to initiate any changes. As a result, One of the most common problems found when diagnosing a (VVT) system malfunction is low oil pressure. So, Without proper engine oil pressure, the (VVT) system cannot operate as designed. Obviously, low engine oil pressure can cause catastrophic engine damage in addition to adversely affecting the (VVT) system. Also, Make sure that the engine is filled to the correct level with the appropriate oil. Finally, If oil pressure is questionable, a manual oil pressure test may be in order.

Other faults that may affect the operation of the VVT system include signal issues with the camshaft or crankshaft position sensors, a faulty MAP sensor (which senses engine load), or even a problem in the PCM itself.

So, Some (VVT) systems operate using individual cylinder actuators, meaning some adjust cylinders in groups. Others adjust all the cylinders on a particular engine bank (at once) with an oscillating camshaft. So, If the vehicle in question has a single cylinder of the (VVT) system disabled, efficiency and performance may diminish minimally. While, If an entire bank has the (VVT) system disabled, a serious decrease in efficiency and performance will be experienced.

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