According to alleged gurus on this board, there is no such thing as false knock.
However, in the real world, something in the engine bay is likely resonating at the same frequency that the knock sensors detect knock below 3k.
Does it happen in all gears?
Is it only when the TCC is locked? IE: When you're cruising on the highway and load the engine to go up a small incline?
What mods do you have?
Check the trans mount and the bottom motor mount located on the underside of the engine near the passenger tire. They can collapse.
