My failsafe boost issue was caused by a bad knock sensor so I did the Maxima knock sensor relocate to the supercharger, which didn't fix it, so I looked for other issues. I chased down a leaky vacuum line on the s/c bypass actuator, and found an intermittent spark plug wire. It appeared that all was in order, so I was stumped, as it was still dropping boost. Then I read that the superchargers can be noisy which can set off the knock sensor. I decided to dampen the KS by mounting it off a 1"x3"x1/8" aluminum bar, right to the s/c. Problem solved. I didn't do the resistor mod because I was concerned about predetonation killing the engine, since there would be no feedback to the ecu.
As for your situation, it would seem that the ecu is detecting a knock, maybe from a lean condition. Is your MAF sensor clean? (be careful when cleaning if you do, as they are very fragile and expensive)