Nissan Repair: Noise when clutching, nissan sentra gxe, nissan sentra

Question
My 2002 Nissan Sentra GXE has some kind of knocking noise and it is more evident when I clutch or put it in neutral. It doesnt make the noise as I am pressing the gas pedal.The RPM needle jumps around and seems to stick more so now since I have noticed this noise today. Could this be a problem with the clutch throw-out bearing or could it be the cable to the RPM gauge being loose and causing the bumping noise?

Answer
Terrell,

If there is noise when you have your foot on the clutch pedal that would be the throwout bearing.  If the noise is in neutral with your foot off the clutch that would be the input shaft bearing.  If your tach is jumping around it would not be a cable since it is electronic.  So, if the tach is jumping then there is something going on with the engine like sparkplugs or fuel injectors if the engine is responding in like kind with the tach.  Otherwise, if the tach is going nuts and the engine is idling fine then the tach or the tach pickup is screwing up.