"Tac Tac" sound when printing with ABS My 3D printer makes weird sounds. When it's at >75% printing speed the extruder motor makes a "tac tac" sound and it goes backwards, pushing the filament back, for a small interval of time. I have tried changing the nozzle temperature and I'm unable to work this out alone. 

Has someone had the same problem?

This is the 3D printer: Geeetech High Quality Wood Geeetech Prusa I3 Pro W 3D Printer Kit.
@Ecnerwal is right: that noise you hear is the extruder not being able to push the filament, and the stepper can't push any harder. When the extruder tries to push harder than it can, it gives up, and the "spring" tension it created in the filament forces it to go backwards a tiny bit. Then it tries again.

Possible causes/fixes:


Temperature too low -- this makes the filament not liquid enough to push through the nozzle easily. For ABS, you should be in the 230-240 range.
Clogged nozzle -- take the nozzle off (while hot) and try heating it with a torch to burn out anything that might be in there.
Bad filament -- If the filament has contamination in it, or is too large to fit through the hot end in places (I.E. it gets up to 1.9mm instead of 1.75mm)
Stepper current too low -- I'm not sure if you can adjust the current that is sent to your stepper motors, but if it is too low, the stepper can not provide enough torque to push the filament through. I don't see the stepper drivers on the site, so I don't know if you can adjust them or not.