anyone can enlighten me the formula to convert the stock Wideband O2 reading (in mA) to AFR reading?

thanks in advance

 

Nope. Can't do it.
You would need a driver circuit to convert it to volts, which would interfere with the PCM's circuit.

 

not possible?

How are those OBD scan tools do it? e.g. Canscan, OBDScan, Cobb AP, EFIDude, etc?

My OBDKey give me these data:
O2 Sens1, B1(WR)***mA Eq. ratio
~~~~~~~~~~~~|||~~~~~~~~~~~~
0.406**************1.179
-0.762**************0.846
-0.387**************0.914
1.727**************1.379


Wondering how to convert them into useful AFR.

 

Of course it's possible. MM is assuming you want to create some additional gauge to hook in, where what I see you asking is "How is the current reading converted to an AFR?"

There's a graph that shows the conversion somewhere, it's also in the shop manual I think, I may have it too if I can locate it, but it's here on the forum somewhere, just hard to find in here with the millions of tidbits of stuff in here.

 

EQ Ratio to AFR: AFR=Stoichiometric/EQ Ratio

 

This doesn't help him. The O2 produces a current that is converted into a lambda value in the ECU. The sensor doesn't produce a std voltage output. He needs the current > lambda conversion 1st.

 

thanks mysql101, you mean I should divide my "mA Eq. Ratio" to the Stoichiometric (14.7) like this:
mA Eq. ratio

14.7 / 1.179 = 12.468
14.7 / 0.846 = 17.376
14.7 / 0.914 = 16.083
14.7 / 1.379 = 10.660

Does this looks right?

 

i think mysql101 is right, found this on other website:


To convert EQ Ratio to AFR, use: AFR = {stoich}/EQ

To convert Lambda to AFR, use: AFR = Labmda/{stoich}

To convert AFR to EQ Ratio, use: EQ Ratio = {stoich}/AFR

To convert Lambda to EQ Ratio, use: EQ Ratio = 1/Lambda

To convert EQ Ratio to Lambda, use: Lambda = 1/EQ Ratio

 

That isn't what you asked.

 

I thought I was pretty clear.

He asked for a "formula" that converts the mA (that means current) output of the sensor to AFR. That means a wire to a meter to a formula.
Not for a formula to convert the calculated output of the sensor (as performed by the PCM) to AFR.

 

Answering forum posts on my phone by the pool sipping coffee.

 

I swear you guys are like a bunch of old ladies . All the guy wanted was the formula - you all go into some semantics argument and never get to it....remind me of my wife lol!

anyway... perhaps the forumla can be derived from the following:

 

thanks a lot guys.

my bad, was confused by the term "mA Eq. Ratio" which provided by OBDKey. After much searching, i've got it now.

 

Is there any reason why the FJO WB AFR unit could not be spliced into the OEM WB sensor wiring to connect to their gauge without it disrupting the ECU , err_ PCM signal?

 

Not sure the correct Stoich is 14.7 or 14.63 which i saw somewhere else.

I just did a logging apply this Stoich/EQ Ratio with 14.1 stoich as i'm running RON97 and here is what I got for my AFR. It doesn't look right though...compare to what I've seen here on this website.

 

Nevermind. Wrong sensor

 

Question.. my stock o2 sensor was cut (while my exhuast was stolen) wanting to know solution eg. can i simply run a wide band o2 sensor to stock ecm and to a a/f guage or no. sorry if its a noob question.. thanks!