DVCrazyCamTAWs6

iTrader: (6)

i'm trying to put together and Excel App for determining Air/fuel by o2 mV output, for editing VE and PE tables etc.

So far i've come up with data in seaching th net that leads to average mVs equaling same air/fuels ratios..

so as far as mV's equaling given Airfuel ratios are very close in test after test given their SLOW responce time, but given that time and it comes equal too have been fair but hard time come by in searching for people that have test for this

has an one ran these test that have a wide band o2 or have come across any data. I would like to gather data from 18 to 9 air fuel ratios and have them converted to mVs

So far i've only been able to gather data around stoich as far as example
(onAverage)450mV Should = 14.86
(onAverage)885mV Should = 12.9

what is everyone else getting, and for the rest of the 18 - 9 go

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http://users3.ev1.net/~borlaz06/VEtablecrack.xls
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jimmyblue

iTrader: (11)

You need to separate narrowband O2 voltages by the
physical exhaust configuration. The EGT pushes the
voltage around a lot more than AFR, in the rich region.

Stock log manifolds showed 870-880mV at 12.7-12.8:1
for me. I had originally tuned for a 910mV target but
that turned out to be about 11.7:1 if I recall.

With enough data you could probably make a useful map
for one particular exhaust configuration. However I think
headers will have wider wall-temp swings and put some
driving history based "fog" onto your curves.

SMOKY

iTrader: (4)

The 02 voltae shuld be around what you stated. 14.7 is supposed to be .450 all the time. The only way to actually see this is if you have an anolog display for your voltmeter with a memory so you can see after you record the data. It will jump around alot when idleing mainly around the .300 to .650 or .750 since it is trying constatly to get it close in the long run to .450.

luv2spd

iTrader: (1)

Anybody have any correlation data with LT's. I've heard that some guys have had 920 mV be 12.8.

DVCrazyCamTAWs6

iTrader: (6)

yeah the LT's would through the numbers way off. but since most of us are using LT's i'm sure our data would be close to people the are stock. This data i'm finding on the net wouldn't be accurate enough coming from cars that differ from ls1s etc. Thats why i'm trying to come up with data firgures from people off the board, most of use running cams and LTs

12secSS

iTrader: (30)

Personally, I don't think this is a good idea. The accuracy of the narrow band O2 sensors drop drastically with usage. For example, if your NBO2 are new and you correlate that data accordingly, after about 20K miles, those numbers will not match up anymore to be usefull for tuning. Anything beyond 14.0-15.5, the NBO2 sensor will not be consitently accurate. It is far better to use the fuel trim to adjust your VE table(s). And for PE modifier, it would be much safer to use an accurate device to measure such critical data. Otherwise it is like smelling the exhaust and concluding "yeah, it smells like 13.0:1 AFR to me".

P Mack

iTrader: (6)

I tried this and there was no useful correlation. Here is what i got from a dyno run, and yes i know i was lean as hell, but if anything that should just mean the o2's are more accurate for the run.

luv2spd

iTrader: (1)

Looks like if you continue that line that 12.9 would lie somewhere between 900-910 or so. That kinda makes sense since guys with stock manifolds are usually around 890.....the LT's allow the egt to cool thus the higher mV.

P Mack

iTrader: (6)

That's where the line would go, but it doesn't matter cause the correlation is so low. Look at the R^2 value. In fact, pick an o2 voltage, say 850 mv, and try to tell me what a/f ratio that is just by looking at the data points.

luv2spd

iTrader: (1)

Yeah, I know they aren't the most accurate thing in the world. That's why I haven't leaned my car out anymore than 920 mV until I get on the dyno with wideband.

DVCrazyCamTAWs6

iTrader: (6)

kinda like this right?



looks close if you ask me. when i dynod my car i was spitting like mid 11s to high 9s in AirFuel mixture which was reading out very high 1050+ to like 1200mVs WOT

now if we had strock headers the line would be more horizontal