The VIS Motors are only fitted to the V6 Petrol Engines not in the Diesel Variants of our Cars.
There are two of these motors in the Manifold one Power Motor and one Balance Motor.
When either of these stop working or both,
the Car uses more Fuel and it can significantly effect the overall Performance.
They are made of Plastic and get contaminated with Oil which stops or Jams movement.
I am a Diesel Man so I'm sure Stocktake and others will correct the above statement,
or put any additional Information required.
A Faulty Removed VIS Valve Motor
Picture borrowed. Thanks.