Abnormal piston slap and triggering of knock sensor?

[Victrix]

I recently acquired a 99 30th AE ej22 with 190,XXXmi. It has what i can only describe as piston slap, but only when warm. On a cold start it knocks for ~1/2 a second(typical), then is smooth and quiet until it warms up. Once it is warm it rattles at any rpm over idle. After a few minutes of driving (with the knock) it will throw a CEL for the knock sensor. Could these two be related? Normal piston slap goes away when warm, but mine is quite the opposite, I have listened to videos of other ejs with piston slap and it is most certainly the same sound. Last week i changed the oil to mobil delvac, and noticed a slight decrease in volume, but not in duration. Is the block getting ready to rid itself of some of that pesky reciprocating mass by showing me what rods look like?

Isaac

[Huffer]

Normally I'd just say piston slap, but because the knock sensor is being activated then it could be more serious. If you have the funds, try seeing if a new knock sensor eliminates the CEL... the sound may not go away but if the CEL turns off then you'll know that the sound is "normal".