I found this very old thread doing a search. There were some mixed opinions there and I wanted to give it a fresh start. The knock I am refering to is not a rod knock or a lifter tick or piston slap. Its like dieseling but the engine starts inmediately and idles smooth. No codes and no knock from the sensor.

It only does it with the engine hot.

 

Did you change fuel recently? Or did you fuel change?

 

No changes in fuel. 93 or better octane rating.

 

Sounds like there may be a bit too much ignition advance for the "start" mode part of the tune.