There is a spread sheet that I have used from the forum. Have a read of this thread.
http://forum.efilive.com/showthread....=interpolation
The adjustments to the VE table will be erratic also if you have not hit a particular cell enough times and obviously that will make the table erratic. The values should be an average of the accumulated data (not a one off number) which will give more accurate numbers for the adjustments.
As for how it looks I am not familiar with the numbers as I use Grams*Kelvin/kPa so my numbers look different however the numbers will depend on my point above.