Negative on the cetane. And its not nailing that it cleared up, it was pinging or preignition.

The nailng sound ( its defintely #2 cylinder) is a bad prechamber I belive, a loose ball??. That sound is actually LOUDER with bio in the tank. much louder in fact. I'm assuming bio doenst atomize as well, and when faced with a bad precham,ber or loose ball, does worse.