How Do I No If Vvt Is Working

[st170dan]

hi i have a st170 and im not sure is vvt has ever been working i can hear no change in exhaust note and allso my manifold flap control unit isnt working and the lambda sensor isnt working when i put the diag on it could this stop vvt from working or could this cause a lose of power. thanks

[artscot79]

if the vvt isnt working youll have a lack of power and eventually the car will go into limp mode the vvt varies the cams so an easy way to tell is get to 2200rpm then put the foot down in 5th there should be immediate pick up