View Full Version : how do i read a A/F ratio gauge

08-08-2008, 10:38 PM
just got a autometer A/F gauge and i was wondering how do i read this thing, it steady goes from lean to rich and within a few seconds it will pause at rich when i get under WOT, so i was guessin this means running rich under WOT, is that correct,that the accurate reading is when it stops bouncing back and forth( i know this is a dumb question but i wanna clearify)

08-08-2008, 10:59 PM
I suppose it isn't a wideband. A wideband would tell you your actual ratio.

This one just tells you if you are rich, lean or stioch.

Basically that isn't gonna be a very accurate gauge and will pretty much just serve to tell you if something is really wrong. That means there isn't really a way to read it.

08-08-2008, 11:12 PM
My buddy has the SAME gauge in his car, they are not very accurate...

08-09-2008, 12:00 AM
Yes, you will be running rich at WOT.

08-09-2008, 02:55 AM
It's "accurate" wheather it's bouncing back and forth or reading steady.

The only time it's not "accurate" is when the O2 sensor is still warming up.

Accurate is all relative.
As already stated, it can only tell you if you're rich, lean or stoich [and how much so, to a point].
It also will tell you if you're running in closed or open loop.
When it's bouncing around the ECU is in closed loop.
When it's not, it's in open loop.

When the car is started cold [coolant below approx 120*F] and when you're at WOT it should be in open loop.
Pretty much any other time it should be in closed loop.

08-09-2008, 04:55 AM
o okay, thanks guys