[geaux_tigerss]

Assume knock is real until proven otherwise. I wouldn’t zero tables.

Are you sure you don’t have any metal to metal contact with headers? That can cause it. It’s worth getting under the car and checking everything. Motor mounts, steering shaft, heat shields, etc.

Are you data logging? Where are you seeing the knock? Same place every time? If so, drop some timing in that region and see if it goes away. Feel free to copy the low octane spark table to the high octane table and data log. Of knock goes away you know you had pre ignition. If not, time to troubleshoot. Bad knock sensors are pretty low likelihood but not impossible. More likely this is knock or metal contact fooling the sensor. I’ve even heard of a pebble getting stuck in the collector space and cause false knock.