Tracking a VOR/NAV course

[cavity]

Does anybody know what parameters in the air file need to be altered to allow a plane to track the vor or nav course more precisely?  The default planes do this very well, but some of the downloaded planes wander back and forth over the course even when intercepting at a low angle.  I wasnt sure if this was built into the model or something that can be altered.  When looking at the default and downloaded air files, most of the values in the autopilot section are identical or very similar, so that doesnt seem to be it.  I hope it isnt hard coded into the model itself.  Thanks for any help.  Todd

[GA_Pilot]

You shouldnt need to modify the airfile to be able to track a VOR. Wind direction and speed will affect your plane, when tracking a VOR.

[cavity]

I am referring to  the autopilots ability to track the VOR/NAV course with no wind or other factors effecting the plane.  Some planes, and not many, intercept the course, start their turn towards the correct heading, fly back over the course, and adjust the other way, back and forth till they reach the waypt.  While one would expect this if intercepting at 90 degrees to the course, it shouldnt happen when intercepting at 20 degrees or less.  Is there a parameter that you can adjust to have the plane track the course more tightly, like the default planes?  Thanks, Todd