subjug4tor;1354743 said:
The lower the number, the richer it is. 14.9 is stoich.
14.7 is stoich for gasoline, numbers below that are rich number above that are lean. You may hear another term, the greek letter lambda. no matter what fuel you are running 1 lambda is stoich. the 14.7 AFR means in order to achieve 1 lambda in a vaccum, you need 14.7 parts air to one part fuel. We dont drive in a vaccum so you want richer numbers to be on the safe side. (keeps temps down, and prevent many problems) your so your idle is a little lean 14.8/14.7=1.007 lambda, around 14.0 would be ideal or .952 lambda. At WOT your 10.0 is a little rich. (10.0/14.7=.68 lambda) ideal safe range would be 10.5 if your running high boost, to 11.5 for lower boost setting (.714-782 lambda.) Lambda is important to understand because 1lambda is always stoich no matter what fuel you use 14.7 is only stoich using pure gasoline.
If you are modding your supra or planning on turning up your boost, its time to start researching fuel controllers. if your just running it at stock boost, your numbers are probably fine, just a little rich at wot, but the worst that can do is leave some black smoke on your rear bumper.