Is my wideband calculation correct

[Bignatesmith]

I have a tech edge wideband controller that reads 0-5v and 9-19:1 AFR unleaded but I want to have it set for e85.
From their website it says (v/0.5)+9=AFR
But this +9 obviously won't work for e85.
So I need to work out what I need to plus it by.
So far I have calculated it to be (V/0.5)+4.08= e85 AFR

I done this by working out the difference between stoich of unleaded and stoics of e85 which I have at 14.7-9.78, the difference being 4.92.
I then minus 4.92 off 9 which gave me 4.08.

Which is how I came up with (V/0.5)+4.08= E85 AFR
So (9.78AFR-4.08)x0.5=2.85V for stoich E85.

But by tech edge website their wideband reads
0.612 lambda at 0v - 1.293 lambda at 5v...
Which fucks my calculations up
Because when I use my calculation for

0volts I get (0v/0.5)+4.08= 4.08 AFR
Which is 0.42 lambda not .612

5volts I get 14.08AFR which is 1.44lambda not 1.293

I understand I can work of lamda values or just pretend 14.7 is 9.78 but I'd prefer to work it out


Any help would be appreciated
Thankyou!!

[Puffwagon]

I haven't tried flashing this to my techedge and it's too cold, dark and late to go outside and set it up to try it right now.

I reckon if you give this a crack it might sort you out tho.

Download latest WButil. http://wbo2.com/sw/zip/WButil06it.zip

Go to the general tab and change the stoich afr to 9.76 which is E85 stoich. Click add, enter the new fuel name and save permanently.

When you click on the "WB Tables" tab you will see that when the "x axis" drop down is set to lambda the correct values will be there.

[Bignatesmith]

Sweet I'll have to give it a go tonight when I get on the laptop,
If that fails I was just thinking about using the lambda scale of the wideband and changing the AFR values to e85 but that will change the stoich voltage from 2.85v and I'm not sure if that will mess things up

[turbotrana]

Alot of tuners, including myself just use petrol lambda scales. Its just what you get used to cause in the early days used the LM1 sensor where could not adjust wideband scales.
Also in the beginning when done the free air calibration I always double check the new style sensor calibrations with my LM1 sensor that I trust.

[Puffwagon]

Alot of tuners, including myself just use petrol lambda scales. Its just what you get used to cause in the early days used the LM1 sensor where could not adjust wideband scales.
Also in the beginning when done the free air calibration I always double check the new style sensor calibrations with my LM1 sensor that I trust.

That's what I do too.

Obviously there are slightly different afrs to target using e85 but I find it much easier that way.

Like you said, it's what you're used to.

[rolls]

Use lambda to tune, it will be foreign at first but ultimately I recommend you get used to it as it will be the same for all fuels.

It only took me about 2 weeks to get used to using lambda as units.

[hiddeous]

Lambda all the way for me. Seems like a natural relationship given the fuel tables are all in lambda?