I've got several examples like the image below where the perimeter either doesn't bond to, or doesn't reach the infill. I tried adjusting the
infil overlap parameter in Slic3r from its default of 25% to 30%, but it doesn't seem to have made a difference. This is on a new Tevo Tornado that's all stock + a petsfang bullseye cooler.
neither speed variations, nor temp variation seems to impact this issue. I'm beginning to suspect that it's related to some sort of play in the y axis, as if you look at the defect in the picture, it's the most pronounced running north/south in the picture, which would be layers along the x axis (meaning their relative position would be impacted by y axis movement instability). I'm replacing the leveling springs with PETG standoffs tonight (I have a BLTouch) and will try again then.
I tried 25, 30, and 50% infill overlap as per a comment request, and that (50%)seems to have improved another issue where the infill on a first layer would often not reach the perimeter shells.
I tried the following print speeds with all of the following temperatures- 190/60, 193/65, 193/70, with 3 perimeters.
That's default behavior. I've also gone to
Perimeters - 80 Small perimeters - 20 Infill - 90 Solid infil - 25 Top solid infil - 20 Bridges - 70 Gap fill - 25
With no visible change in this outer perimeter behavior (the faster set of numbers is what I print with in general).