The gauge works fine at idle it is a small range that you can tell the mixture but while cruising, the light emcompass almost the whole gauge, is this normal because it seems kind of usless to have one?

 

you have a O2 guage?

 

Well I meant an air/fuel ratio gauge, sorry for the ambiguous post.

 

air fuel ratio guages do not do much at part throttle cruzing. (it may seem to bounce back and fourth this is because the computer is always trying to get the optimum a/f ratio. the guage should always be at rich when you are at full throttle. thats the only thing that its good for (besides it looks cool while you are driving.)