Nissan Repair: Fuel knock sound, magnetic signal, knock sensor

Question
I have an 02 Maxima and once the engine gets warm, between 1500 and 2000 RPM, it almost sounds like a fuel knock coming from the front of the vehicle.  It is in time with the RPM's.  I have brake torqued to see if it happens when im not moving and the noise isnt present.

Answer
Wade,

You could try super unleaded fuel and see if the knock goes away.  If you are already using premium then I would think you should be throwing a code for a knock sensor.  Go to Autozone or Checker and get the codes read for free...  Even though the check engine light is not on an error code is stored in memory for many ignition cycles as a pending code.  Email me back and let me know what you find.

Also, if this is not engine noise you could have a broken motor mount, rear, that can cause noise as you drive.  The motor mounts are freeo-fluid filled and become soft at idle and harden via electro-magnetic signal once you start moving.  My 2000 Maxima SE lost it's rear mount, the ferro-fluid leaked out, looks like old engine oil, and then the engine knocked around when you drove.  And, it was pronounced at the RPMs you indicate.  Check it out...