Flex fuel patch (Stoich value)

[mourat]

My question is around what happens when the patch is applied.

I've noticed that after applying the patch, the FA Stoich value is no longer 0.0722 like it would normally be without the patch. Now at 0% I see a value of .0680.

Does this mean that the whole time there was no 6% ANN Bias. And in fact, all we were looking at (Pre-patch) is a 10% ethanol value?

Example -

Before patch (FA value 0.0722) @ 0
After Patch -

0% = 0.068
10% = .0710
50% = .0846
85% = .1015
100% = .1111

So is this an error after the patch? If so, should I change 0% to 0.0722 as it was pre-patch?

Thanks!

[B00STJUNKY]

My question is around what happens when the patch is applied.

I've noticed that after applying the patch, the FA Stoich value is no longer 0.0722 like it would normally be without the patch. Now at 0% I see a value of .0680.

Does this mean that the whole time there was no 6% ANN Bias. And in fact, all we were looking at (Pre-patch) is a 10% ethanol value?

Example -

Before patch (FA value 0.0722) @ 0
After Patch -

0% = 0.068
10% = .0710
50% = .0846
85% = .1015
100% = .1111

So is this an error after the patch? If so, should I change 0% to 0.0722 as it was pre-patch?

Thanks!

Straight gasoline stoichiometric ratio is 14.7:1. That's 14.7 parts of air to 1 part of fuel. Did you know that the FA value you're talking about is simply the inverse of AFR, or, in other words, FAR (fuel to air ratio)? Know how to figure out inverses? Divide 1 by the value you wish to find the inverse of.

1/.068 = 14.7

This should answer your question, and the rest should make sense now.

[mourat]

That I know, lol. Otherwise I wouldn't be here. If you look at what I'm asking. Normally Hellcats are told to be FA Stoich at .0722 which is around 13.85 Air Fuel with a 6% bias built into the file. Meaning, that when your hellcat widebands are showing and command 11.35 Air fuel, you're actually at 12:1 or so at the tail pipe. It's an annoying part of tuning these things.

However, ever since the FlexFuel patch. Now at 0%, we're FA .068 which is 14.7. My question is, why is it that after applying the patch, FA goes from .0722 to .068?

[B00STJUNKY]

That I know, lol. Otherwise I wouldn't be here. If you look at what I'm asking. Normally Hellcats are told to be FA Stoich at .0722 which is around 13.85 Air Fuel with a 6% bias built into the file. Meaning, that when your hellcat widebands are showing and command 11.35 Air fuel, you're actually at 12:1 or so at the tail pipe. It's an annoying part of tuning these things.

However, ever since the FlexFuel patch. Now at 0%, we're FA .068 which is 14.7. My question is, why is it that after applying the patch, FA goes from .0722 to .068?

Using Lambda instead of AFR would help grasp things a little easier. It's not really a bias. It's legitimately 6% more fuel mass to achieve 1.0 Lambda for a true ratio of 13.85:1. But, since you're using a wideband that's calibrated for straight gasoline, it shows you 14.7:1 instead.

Another thing to look at, before having the flex fuel patch applied, the OEMs assume that most folks are going to be using standard fuels from standard pumps, all of which have at least 10% ethanol mixed into them by default these days. Hence why the stoich value was set to .0722. It's accounting for the ethanol that is already present in most commercially available gasoline.

Now that you have the patch applied and it can determine ethanol content percent, it only stands to reason that when it determines ethanol percentage is zero, then fuel mass for stoich will be .068. whereas when it detects that ethanol content is 10%, it will use .071 as stoich fuel mass, and so on, and so forth.

[mourat]

Perfect! This is exactly what I was getting at. 10-15% ethanol is found in my gasoline. Now with the patch, and zero ethanol content in 94 octane fuel here in Canada. I should see the same FA / AF between what the external wideband and the WB 02s show.

Also contacted HPT and they provided the same response. Thanks BoostJunky

[06300CSRT8]

How does this patch allow the ECM to actually “see” the ethanol content?

[B00STJUNKY]

How does this patch allow the ECM to actually “see” the ethanol content?

I believe Dodge uses the O2 sensor feedback along with some algorithms (I want to say fuel level readings play into it) to determine if fuel supply has changed. I remember reading an article on it at one time, but I can't find the exact article I read.

But this one might give you a little insight:
https://www.google.com/url?sa=t&sour...8nvdC0TMrmmTqD

[06300CSRT8]

But the question is can it work on a non-wideband equipped car? My guess is no. But does this patch enable wide-band feedback reading for the ECU?

[Homer]

Is it possible to add factory wideband? I would be awesome if all it took was to get HC engine harness and stripping the O2 connections off of it!