Judging from your settings I'm going to assume you're trying to use the INTOSC.

If so, you need to set the CONFIG to use it. That's what controls what happens at powerup...
trying to setting the OSCCON register is a run-time setting, so it relies on the thing running in the first place.

The default INTOSC setting is 8MHz, so it'll run at that speed until you change it with OSCCON.


Try this:
Code:
  CONFIG  RETEN=ON, INTOSCSEL=HIGH, SOSCSEL=HIGH, XINST=OFF, FOSC=INTIO2, PLLCFG=OFF

'then later you can change it
OSCCON = $70     ' IRFC[2:0] = 111 (16MHz), SCS[1:0] = 00 (primary CONFIG osc setting)
' set PLLEN (optional, 4x16MHz=64MHz)
'OSCTUNE.6 = 1