AFR for E10 and wideband O2

[alextzi]

Ok, so I set Stoich to 14.2

Tuned VE, no problem, using 1.0 in the open loop equivalence ratio table

in the PE table, set the equivalence ratio to 1.13 (which 1/1.13 is a lambda of .885).

The wideband o2 is calibrated to read out AFR for Gas. When doing the WOT run, the Wideband 02 showed an AFR of 12.55.

Now if the wideband o2 shows 12.55 on a gas scale where 14.68 is stoich, this would correspond to a lambda of 12.55/14.68= lambda of .855, but I commanded lambda of .885 (through an equivalence ratio of 1.13).

Can anyone explain why this is the case?

Again, this is E10.

[Asylumwarp]

Sounds like you tuned it before you set your stioch to 14.2?

[Iam Broke]

VE table may need some work yet. Did you tune it in the same approx temp and humidity you are running now?

Problem with running open loop is that things shift and it's better to be rich like you are than lean. You don't list your set up but a .88 lambda PE on a port injected engine seems pretty lean to me. I ran that on a turbo direct injected LNF though.

Too bad your WB doesn't display lambda, it'd make your life easier. AFR confuses me on alt fuels since I learned to tune in Lambda.

[Asylumwarp]

I think the answer you are looking for is this.

http://www.enginebasics.com/EFI%20Tu...%20Basics.html

The wideband will read lambda, and then convert to your set 14.7 ratio. No matter what fuel you decide to use, your wideband reads in lambda 1.0, then reports 14.7, So even though you set your pcm to read 14.2, and 1.13, your a/f ratio gauge is correct. You are seeing 12.55 on your wideband, or lambda 1.0 converted through the gauges brain to 14.7, or 12.55.

Your computer does not read in lambda, it reads in a/f ratios. It doesnt know what fuel your using, hence setting it up. Your gauge does know. You,re ok.

[jim2092]

Or said a different way, if you want your WOT AFR to be the same for E10 as it was for regular gas after changing the stoich you will also have to change the EQ ratios.

[Asylumwarp]

The wideband reads correctly no matter what fuel. 14.7 is 14.7 regardless of E10, IF your wideband uses Lambda as it SHOULD, then converts to 14.7. If you tune with wideband, at stoich in PCM at 14.7, and you enable your stft, it will show lean by like 4-5 points, then move your stoich to correct for e10. Then do a WOT run, set PE as needed to correct for it richening up. All will be well