Can anyone explain to me better about A/F? Ok my truck has a A/F of 10.9-1 . iIt is a lil on the richside but its winter time so i am going to just leave it like that for now. Ok my question is? Is it 10.1 % Air to 1% fuel Or how does all this work out. I am new to the SC world so just trying to learn as i go.

 

You are correct. 10.9 parts air to 1 part fuel.

 

Yep! dc is correct. Engs. run/need much more air/oxygen than fuel to run properly.

Dan

 

Its not percent its parts...
10.9 parts air for every part fuel ...
The 10.9 in your case means for every unit of air measured there was 10.9 times as much air as fuel. The higher numbers the leaner the mixture because there is more air for the same amount of fuel. 10 to1 is richer than 13 to 1

The numbers most people worry about are at WOT above 3000 rpms... Sometimes you will see higher A/F at low rpms at the begining of the run.. untill you go to WOT the computer is trying to keep the A/F at 14 to 1

Doug

 

so the computer tries to maintain 14.1 before WOT? i thought it was 14.7? (only saying that because most dyno sheets i've seen at tip in the AF is at 14.7 @ 3300 rpms or so...)

 

14.x to 1