A little history... we have an issue with a sticking wastegate piston. I'm not convinced its ONLY that. What happens is while driving at steady throttle, generally lower RPM, the wastegate pops open and stays there .It is sticking; we just tap it back towards closed and it pops closed. That's been happening for a few weeks.
The other day it started this: boost will fluctuate inexplicably... so we might be driving along loaded and suddenly the power drops. Notice the boost gauge shows a boost pressure loss, then increase at the same time.
I don't see why the wastegate would open under a condition where it isn't building boost pressure, so I'm thinking the issue might be boost pressure sensor.