Porangi Toa are originally Krana controlled toa.  Then they , one way or another, free themselves of the krana causing them to go crazy.  They can achieve unbelievable speeds and can fly.  The speed mask has absolutely no affect on them.  They fight for no one and usually end up blowing them selves up from continued insanity.  Their self destruct destroys them and the 100 closest Krana.  It also leaves a small crater and destroys anything in a 10 foot radius, but takes a full mintue to charge it.