CV Joints

• You will notice metallic clicking sounds upon acceleration -- and during turning -- if the CV joints are failing. Check the CV boots, which are located behind the tires on your Maxima. If the boots are cracked and aged, the CV joints have lost their lubrication and are in the process of failing. Replace the CV joints before more extensive repairs are needed.
  
  

Engine Mounts

• Engine mount failure may also explain loud, metallic knocking-sounds coming from your engine; this typically might occur during acceleration, when the engine works harder. Engine mounts are usually an inexpensive fix, although somewhat complicated. Replacing the mounts requires lifting your engine with a floor jack, removing the old mounts and installing new ones.
  
  

EGR Valve

• If you hear metallic pings or knocks as your Maxima accelerates, your EGR valve might have failed. Other problems related to the EGR valve can include carbon buildup in the piston chambers, bad ignition timing or a bad tank of gas. Switch to a higher fuel grade to see if the pings and knocks decrease or go away.