OK, so we got hit by a cold snap today, about 20F colder than I've ever logged the car. I actually recorded an IAT of 5F as I started up the car! For some reason, the car was knocking LIKE MAD today. Very, very frequent knock and HUGE corrections (like 5-7 degrees FLKC+FBKC). Once the car got hot enough than the under-hood temps pushed the IATs up into the 60s (about 30 minutes of driving), the knock dropped back down to about what I've been seeing lately.
At first I thought maybe the colder air was dense enough to raise my load (increased load->increased knock), but once I looked at the data again, it's was having a fit even at part-throttle where the loads were no higher than I had been seeing (~0.6-0.8g/rev). What the heck was going on while it was so cold?