Knock light on idle
 

Back story : Knock light (Which makes the CEL blinks fast) Never went on before. TS never read overheating

Now: finally connected Wideband to MS. TS reads WB perfect. BUT, now for some reason, knock box on TS and CEL blinks on. just on idle. When i blip or hold throttle, it goes away.
Also, for some reason, the Coolant temp started reading higher than what it is. It goes past 220F+ just idling.

So i disconnected WB from MS, and knock goes away, and Coolant temp immediately reads normal.

What could be making all this happen, just by me connecting my WB to MS?

Tune attached if someone would be willing to see,
MS3 enhanced Rev built.

You probably grounded the wideband through the DB37's black/green wire, which is an analog ground, instead of grounding to the engine.

I presume the black/yellow ground remains acceptable for the LC-2 (in lieu of the direct engine ground)?

Yes for the Basic MS3, the Enhanced MS3 doesn't have one.