bagodoosh

wow. talk about being absent minded.
i drew a gridline threw the lambda graph, then came to realize i had done the same thing 3 weeks ago.

anywho.. previously:

<img src="http://bagodoosh.home.comcast.net/s4/lambda-afr.gif">

and now..:

<img src="http://bagodoosh.home.comcast.net/s4/lambda_graph.gif">

<img src="http://us.i1.yimg.com/us.yimg.com/i/mesg/emoticons6/39.gif"> someone needs a life here.

Oo.et.oO

at least you got the same results. :-D

ImolaRocket

Am I correct? This graph converts our O2 voltages to standard AFR ?

bagodoosh

the original graph was posted by todd/a.w.e. i believe.
i just put a grid to make things easier.

i am in the process of formulating the graph -- but not having so much luck.

bagodoosh

this allows you to just feed it a voltage, and it'll formulate the lambda. it's not 100% accurate, but it's pretty close. for the accuracy of AFR which is 1 decimal point, it seems to work.

i split the graph into 2 sections. there's a linear part between 150 - 800mV. and the curve from 800mV beyond. i've avoided any values below 150mV. so any AFR leaner than 14.7 won't be calculated, which should be fine for WOT.

here's the grid once more, reoriented:

<img src="http://bagodoosh.home.comcast.net/s4/lambda_graph2.gif">

and here's my emulation:

<img src="http://bagodoosh.home.comcast.net/s4/lambda_graphe.gif">

formula for the linear part: 150 &lt;= X &lt; 800

(12.9-X)/12.75

formula for the curvature: 800 &lt;= X

-130.31*X^4 + 395.56*X^3 - 450.41*X^2 + 227.84*X - 42.214

excel formula:

=IF($D8&lt;0.15,"",IF($D8&lt;0.8,(12.9-$D8)/12.75,-130.31*$D8^4 + 395.56*$D8^3 - 450.41*$D8^2 + 227.84*$D8 - 42.214))

this allows you to calculate directly on the Block 033 sheet.

to calculate AFR just multiply lambda by 14.7. "format" the resulting cell as a number with 1 decimal point.