I'm having an odd issue with my 2008 R56, 112K miles. Under certain circumstances it throws the following codes:

2D9C - Knock sensor, signal
2D50 - Super knocking
2885 - Boost-pressure control deviation, plausibility

The circumstances are:

1) HOT (like 85F+) or humid (like 100% RH) or hot and humid.

2) Acceleration with 75% or greater throttle with engine RPM starting about 2K.

Never happens when it's cool or dry and almost never if the engine RPM starts above about 3K RPM when accelerating. I can clear the codes and they often will not come back for days or even weeks.

Where should I be looking for issues?