gus do you know lambda and afr are one and the same thing,. just different ways of measuring just that the way your question is worded like you want both.

lambda 1 = 14.7 afr
lambda 0.86 = (0.86 X 14.7) 12.6 afr
lambda 1.2 = (1.2 X 14.7) 17.64 afr