DEFI A/F guage and it's functioning...

[Lipster]

This is specific to JUST the Defi D series A/F gauge...

Does anyone here use this gauge? It is based off of the 1 volt O2 sensor, but, it's output is based upon the ratio output.

If I am idling, the gauge tends to sit at 14.5:1 -- but on WOT, the output doesn't do much else.

Letting off of the throtle will drop the ratio to 17:1, which seems right to me.

I understand the output will not be accurate, but, I am just looking at trends... (And the gauge was free)

Any experiences with this gauge?

I tapped off of the ECU based off of the 2004 WRX (pin numbering was from ravens _blade website - my first funny issue was I was looking at the pin numbers and looking at the actual wire plug -- not the pins on the ECU itself... geez...)

[ryland]

I think it is because the stock 02 sensor is a narrowband, and you need a wide band sensor to be able to accurately measure your AFR.

[subieworx]

I think it is because the stock 02 sensor is a narrowband, and you need a wide band sensor to be able to accurately measure your AFR.

He said he knows it's not accurate. The fact that it is narrow band has nothing to do with it reading strangly. I think there is something weird with our O2 sensor. I remember reading that it works off an inverse 5 V signal or something.

[Lipster]

I've had it a few days now and I seeing what it is trying to tell me (again, yeah... I know it is narrowband).

I was curious to see if anyone had dealth with this type of gauge before; narrowband with the ratio as the output, not a bouncing blinky light.

It seems to lock into 14.7:1 at idle, which seems about right...

The thing that I think is actually cool with this is like I said -- you can at least see trends.
I.E. Now full throttle pegs the needle past 10:1 (like 9:1). Since it previously would only measure around 14:1, in essence, I am watching the computer learn and adjust as I drive it more.
When I had my perrin BOV on it, I would run WOT then shift, it would read a quick rich then back to lean (I didn't get it properly adjusted yet). I put my stock BOV on it and now when I run WOT and shift, the ratio doesn't dip anywhere near what it was with the perrin.

I guess at this point, the post is more my experiences with this gauge and watching how the computer is learning my engine and driving and also how different components MIGHT impact the engine... TO A DEGREE since it is a narrowband gauge.

[ryland]

I think the results you will get from that thing are sketchy at best.

[Lipster]

Right -- trends...

I dont think these things are hideously way off -- not accurate -- but not HIDEOUS. If your O2 sensor goes bad, your car runs like crap, so, there has to be some level of accuracy with these things FOR TRENDING.

[ryland]

Well, there is a big big difference between 10.5:1 afr and say 12:1 afr. I doubt it would be accurate enough to distinguish between those two values, and that could be the life/death of your engine right there.

[Lipster]

Right. I never said I am tuning against it. It is, again, trending.

For tuning, using wideband, egt, and dyno are the best ideas.

Anyway, I think this thread might be hitting a wall.