Okay I'll hazard a guess. You said not to go on boost before you try this, and I've seen various posts that say the ecu will gradually add timing until it detects knock. If this is a running average of knock correcton, and if the ECU code feels safe giving absolute max possible advance at this low rpm, and boost level, then ....
The fastest way to build that running average is to go to the point on the rpm / boost scale the ECU is most willing to give max advance, and hold there long enough to max out the average.
Am I close ??