O2 voltage to A/F ratio

[Wufei]

Wonder if anyone knows the voltage signal correlation to the A/F ratio on the stock O2 sensor. I know it's not very accurate as the correlation isn't linear, but it's still good enough for a rough conversion right? Want to setup my A'PEXi AutoTimer so that the A/F ratio actually has meaning.

 

[cxx]

0.5 Volts = 1:14.7 air fuel ratio if I remember correctly.

 

[1990EclipseGSX]

Wonder if anyone knows the voltage signal correlation to the A/F ratio on the stock O2 sensor. I know it's not very accurate as the correlation isn't linear, but it's still good enough for a rough conversion right? Want to setup my A'PEXi AutoTimer so that the A/F ratio actually has meaning.

The value you read on your TT will still have no meaning. .90V on the stock 02 could be 11.0:1-13.0:1...

Get a wideband .

 

[Wufei]

The value you read on your TT will still have no meaning. .90V on the stock 02 could be 11.0:1-13.0:1...

Get a wideband .

I mean to

Huh, I thought that it's just that instead of a linear relation, the relation between V and A/F is like this graph:

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[GVR4592]

If it was only that simple we wouldn't spend hundreds of dollars on wideband setups. The fact is no two cars are the same when it comes to O2 voltage, and it's pointless to use it as an indicator of A/F ratio.

 

[Wufei]

Ah, thanks for the info! How much of the area around .50v (which cxx is right in remembering is 14.7) is useful? There's 8 setting points on the AutoTimer so I'd like to put maybe 4-6 of those points around .50v. Right now I've got one right at .50v and one at .48v and .52v, those are still ok right?

The wideband is the next mod on the list. Just trying to tweak what I have right now.

 

[Staytuned]

Dude you don't want 14.7:1 anywhere along your WOT log.

Say bye bye to your engine. If I was to give you a hint at what might be very rough guess as to what narrow band voltage to look for at WOT it would be .92v on a 2g. That could be anywhere from 10:1 to 11:1 ....but that's safe for now.

 

[Wufei]

Dude you don't want 14.7:1 anywhere along your WOT log.

Say bye bye to your engine. If I was to give you a hint at what might be very rough guess as to what narrow band voltage to look for at WOT it would be .92v on a 2g. That could be anywhere from 10:1 to 11:1 ....but that's safe for now.

Yeah, just trying to make the best use of the narrowband.

 

[shortydtp]

best use for the narrowband. would be leaving it alone. and let the ecu use it , for your idle and cruise. get a wideband for WOT.

 

[1990EclipseGSX]

Dude you don't want 14.7:1 anywhere along your WOT log.

Say bye bye to your engine. If I was to give you a hint at what might be very rough guess as to what narrow band voltage to look for at WOT it would be .92v on a 2g. That could be anywhere from 10:1 to 11:1 ....but that's safe for now.

Read through this link... The last little paragraph and the pic of the DSMLink log especially. AFR ranges from 10:1-13:1 while the O2 voltage stays right at .98V on a 2g....

http://www.posracing.net/AFR.html

 

[Staytuned]

Yeah that's fine but the last two years on pump gas I have run .90v and have seen anything from 10's to 11's on those numbers. Also seen a .88v around 12:1 at WOT...so I am pretty sure that .92v would be a safe guess for him.

 

[1990EclipseGSX]

Yeah that's fine but the last two years on pump gas I have run .90v and have seen anything from 10's to 11's on those numbers. Also seen a .88v around 12:1 at WOT...so I am pretty sure that .92v would be a safe guess for him.

That is great for you. But what makes you think his car will behave like yours and not like the ones that span the whole rich to lean spectrum on the same voltage?.

A safe thing to do would be to not even bother with this, because it is shooting in the dark.

Guesses lead to blown engines....

 

[Staytuned]

There is no doubt in my mind that all cars are different and that a wideband is the way to go. But I merely suggested a what works for me and the other Talons in my town that are tuned with the Link and a wideband.

 

[GVR4592]

The bottom line is the narrowband isn't a good indicator of A/F ratio. Using it would be a huge waste of time. They are never the same from vehicle to vehicle, so lets forget about it and let it rest like the dozens of other worthless narrowband threads.

 

[Defiant]

Great idea.