I have a TIR4 that I bought a year ago but only used it for a week. I was having problems trying to look behind me.
I found that if I reset all the custom views for a plane using the "home" then "F10" keys for each view, then the trackIR panning was nice and smooth, but it was really hard to look around the headrest to see behind me. I would turn my head to see the 6 view, then when I tried to lean to see around the headrest the thing would stop tracking and get stuck.
If I set custom views so that the back-left and back-right views already looked around the headrest then I found that trackIR seemed to "snap" to those views instead of smoothly panning with head movement, which I found really annoying.
I could never get the right setup so I gave up after a while, and went back to the old left hand on the numeric keypad for views.
Do you guys clear all the custom saved views for each plane when using trackIR?
Custom views have absolutely nothing to do with TIR and smoothness
UNLESS you're using your hat switch. I recommend that you disable your hat switch views to force yourself to rely only on TIR.
If your TIR seems to "snap" to particular views it probably isn't due to extra light sources. If that were true you'd have problems no matter where you look. The problem you're having is that you probably have way too much deadband set in your profile. This deadband tends to draw your view to the major axis, this is doublely true looking forward and aft since this is where the pitch and yaw axis intersect. To minimize the deadbands make your curves flatter in the center and with the center point well above zero (on the rotation speed axis). My pitch and yaw curves have a very, very shallow V that are actually almost flat with the center position set to 9 for yaw and 11 for pitch. X, Y, and Z curves are also almost flat with the center point set at five. Also, my speed is set to 1 and smooth set to 30.This is all personal preference but I personally hate the deadbands so I've eliminted it in all of the axis of my profile except roll.
The reason your views are getting stuck when you check six is probably because you're exceeding the limits of the TIR tracker (i.e., you're outside the camera's field of view (FOV)). It helps if you setup your system with greater physical distance between the camera and your head (the farther away you are the wider the FOV). Either sit farther back or move your TIR camera farther away. Hard to say what will work best for you since I don't know what your setup is. Lean forward a bit when you center TIR. That way, when you relax back to your normal sitting position your in game head is toward the back of the cockpit. When you turn to check six your head pivots around so that it's now toward the front of the cockpit which makes it much, much easier to see around the headrest. This minimizes the movement you need to do when checking six and minimizes the chances you'll go outside of the camera's FOV.
I seriously doubt the problems you describe are caused by light sources behind you but to check select your camera view. This will let you check for light sources that can interfer with tracking and also let you move your head in the same way as you would in the game and see if you're going outside of the camera's FOV.