Is that 139 BLM reading at WOT? If under boost, the BLM's may be locked by your chip to 128. If that is the idle or cruise BLM reading, that would not be contributing to your knock condition under boost. a 139 BLM means its running lean and the ECM is adding fuel...but with the looks of your O2s its rich...unless thats WOT O2s your posting......
Gotta keep you #'s consistant, please provide WOT #s, the reading of your IAC and BLMs at cruise/part throttle/idle will not effect your WOT / under boost KR condition.
And a BLM of 139 isn't bad, the computer is doing its job making the A/F what it should be, which would be the same A/F if the BLMs were 128.
I would suspect timing may be too high if adding the 100 octance or xylene mix cures the problem. Also, get a manual fp gauge that you can see while under boost to be sure your getting 1 lb of fp added for every lb of boost.
And octane booster like 108+ in the can is garbage, that will only boost your octane for a tank of gas by about 8 points, which means 93.8 if you have 93 pump gas in the tank, it does not mean 93+8=101 octane! Go to a paint store and pick up some Xylene and you can find Marvel Mystery Oil at most auto stores or Walmart..its in a red bottle.
