A simple E10 question

Hey all,

I found out that since all my fuel sources here in Hawaii are pretty much all labeled "up to 10% ethanol" I should really set my stoich point in my tune to 14.4. After all the years tuning my car I just learned about this...even though this topic has been beat to death! Anyways, I just set my stoich point in the tune to 14.4 for the whole splitting the difference philosophy. I clearly understand that. I run a closed loop speed density tune with ltft's turned off. STFT's only until I go into open loop (PE/WOT) I tune my VE table using STFT's with the exception of any open loop operation. Those cells get treated by my AFR % error wideband calculations. Seems to work great for me. Quick and easy to touch things up if need be.

So whats my question? I don't want to tune in lambda. I like the AFR readout...it makes me all warm and fuzzy inside. Since all my part throttle/closed loop driving is set purely on the factory narrow band sensors (CLSD tune)I'm not too concerned with what my AFR readings are cruising around. I have not changed my LC1 wideband settings to 14.4 as stoich. Should I? If so, do I have to change anything in my VCM scanner as far as the formula that's set up to give me an accurate readout via the AC pressure sensor....I don't have pro so I use the ac pressure signal formula route.
100*((([PID.7101]/.5)+10.1)-[SENS.121])/[SENS.121]
Based on this formula the only thing that would change is the voltage readings under PID.7101? So I wouldn't have to change anything in the scanner, correct?


What I really need to know is what PE AFR setting I should run now?
.87 lambda with E10 is 12.5:1. This is what I set my PE to in my new tune file...1.176 which is 12.5.
Now if I do not change my LC1 wideband settings to 14.4 and leave it at 14.7:1, but am using 14.4 in the tune as stoich, would I see 12.78ish on my wideband telling me its actually at 12.5:1 or .87 lambda? .87x14.7=12.78

If thats the case i'll leave all my wideband and scanner settings as is and just know that 12.78 on my wideband is really 12.5 or .87 lambda meaning all is well and I'm not going to burn up the motor running lean or overly rich which may sacrifice power.

Actually, unless you change your WB's stoich set value, it will still report the 12.5. This is because the WB actually works in Lambda which means that a "perfect burn" or Stoich AFR is always 1.0 regardless whether it is gas, E10, E85 or straight ethanol. The thing to remember is the WB actually measures oxygen to do its thing. That being said, it would then take say a result of 1.0, look to see what you have set the stoich AFR to in your meter and displays that value. If you set stoich to 1000000, then that is what it would display. Concurrently to arrive at a 15% enrichment say for NA, you would still go with 15% based on 1.0 stoich.

This is why in todays fuel mixture inconsistencies, it is best to log and work in Lambda.

Hope this hopes.

Ed M