I have a 93 too and sometimes, when it is 90F or higher and I'm going up a grade in high gear, I can hear a ping or two. I make it a habit to run 93 in the summer and it decreases that tendency noticeably. Also, it was much worse before I replaced the knock sensor. Make sure you torque the bolt properly, which I believe is in inch pounds. It is sensitive to the torque and improper torque will not allow it to function as designed. BTW, there is no way to test the newer sensors without an oscilliscope. The old bang a wrench on the block and watch the timing mark isn't reliable.