Hooked a scope up to SCL and SDA. Sits at plus 5v when the program isn't running. That is with no added external pull up resistors. Once I start your program, both are producing a 5v DC square wave. Not a lot of difference seen in the output between when I attach 2k pull up resistors as it was already pulled up and down cleanly. Still moves down to zero and up to +5v cleanly without. I can see the frequency steps the program produces. Looks like the mega does work. So its either my software (wire program?) or the actual i2c devices. Wish I had one I knew worked.