well first of all remember what a wah is and what it does.

second get rid of any ground loops by plugging everything in to a signal power strip or even better a power conditioner.

Next turn off all fluorescent lights and CRT type computer displays as your pickups will pick up particle emissions from these sources.

If this doesn't work try shielding the cavity housing the electronics of the guitar.

Sometimes when you are recording it comes down to moving about till you find a spot that gives you less noise than the others.


Last resort is a noise gate though this will only serve to kill the signal to your amp during times when you are not playing.