using 14.047 for desired AFR and not 14.63?

[98 tigershark]

I have read a few articles on that as well but wasn't it determined to be not reliable with most all of the non flex fuel PCMs.
If I recall correctly, the Ethanol fuels can trick the O2 sensors and therefore the Long and short term fuel trims.
That was the conclusion right?
98 tigershark

Didn't someone else explain how the newer OSs use STFT to detect Ethanol and make changes in the tune rather than using the sensor , think it was in the same thread .

[mr.prick]

So STFTs change EQ1 in a GEN3 OS?
I don't recall reading how STFTs would detect what the Ethanol% is
therefore changing EQ1 automatically.
Newer OS' have a more defined stoich table per Ethanol%

The OP has a C5,
{B3601} is static with no way to change EQ1 for varying Ethanol%.
Example:
If EQ1 is set for gas (14.6AFR) and you have E10 (14.1AFR) in the tank
you are still going to command 14.6AFR not 14.1AFR and
all other fuel tables are stuck at the EQ settings based off {B3601} (14.6AFR)

Ideally, you just set your defined stoich point in the table to whatever the chemistry of your fuel really is and leave it alone. (I use 14.13 for e10, 14.64 for "normal" gasoline, and 14.4 to split the difference if we're unsure of what's in the tank)

This answered the original question.
If you want to run more than one fuel type/mixture things complicated
with a stock C5 OS,
it's either one fuel type or the other.

[gmh308]

Team,

It looks like GM's Virtual Fuel Sensing "technology" is being alluded to.

A few years ago GM announced that it had developed "Virtual" Fuel Sensing for Flex Fuel vehicles as an innovation that avoided the requirement for a "real" flex fuel sensor. The $700 list, $400 street sensor that sends fuel composition info to the PCM/ECM.

Read about the tech details on the "real" sensor here. It also details the FF GM vehicles the "real" sensor" is used on.

http://www.megamanual.com/flexfuel.htm

In short it provides a 50 - 150Hz square wave to the PCM/ECM to indicate ethanol content, and is smart enough to detect fuel contamination, and indicates fuel temperature via modulating the pulse width of the square wave.

The operation of GM's Virtual Sensor (VFS) is described in the GM patent
attached in "patent speak". Enjoy the read .

GM-VFS US Patent 7159623.pdf

In short "it" uses fuel tank level changes to decide the tank has been filled and runs a cycle using the O2 sensors & trims to help decide what the E content is and then references various other E tables in the PCM/ECM to get the timing and the fueling optmised for E.

Interesting stuff.

[CalEditor]

Team,

In short "it" uses fuel tank level changes to decide the tank has been filled and runs a cycle using the O2 sensors & trims to help decide what the E content is and then references various other E tables in the PCM/ECM to get the timing and the fueling optmised for E.

Interesting stuff.

I am under the impression that the fuel level sensor need to be connected on conversions also to switch back to the High octane table. If you have a conversion with out a fuel level sensor you will be stuck on the low octane table.

funny how GM uses that sensor for more than just the EVAP system.

[gmh308]

I am under the impression that the fuel level sensor need to be connected on conversions also to switch back to the High octane table. If you have a conversion with out a fuel level sensor you will be stuck on the low octane table.

funny how GM uses that sensor for more than just the EVAP system.

If you log the Octane scaler, and it is above zero, you will see it ramp back down over time towards zero. Sometimes this occurs quickly, sometimes not. Seems to depend on frequency and severity of knock. Which makes good sense.

[98 tigershark]

That is pretty cool stuff. Thank you so much. I had seen some thing like this awhile back last year. Didn't they have a separate fuel tank specification that was patented separately but must be used with this system? I think is was a sort of chopped top of pyramid style tank. I am going off of memory here so take that for what it is. Do you know anything about the special tank for this, I heard only heard of this but I think it is true. What say you gmh308? gm General manager? So what do we do?
Thanks again as that is really cool. I am curious as to how you found that,
Very grateful,
98 tigershark

[Chevy366]

OK Chevy366,
I give up, I cant find the place that addresses the Earlier PCMs (non flex fuel) and Ethanol fuels. Can you please post the link, Pretty please. Before you visit your still would be nice. I had a tractor too (A Kiote), but my cows are now eaten. Pigs are much easier.
98 tigerhsark

Sorry , I think I used 'Ethanol sensor' in search criteria . Try that , if not I will see if I can find it again .
Oh , watch the country hick comments , not funny !

[98 tigershark]

Hey Sorry Chevy366,

I do have a tractor, I did raise cows and I do occasionally raise pigs and I have a small farm.
Even though I have never hunted from my deck I could!!
I do live in the sticks and I like Jeff Foxworthy, I think I got his name right.
We are a little sensitive today so sorry! Because I live in the sticks it is hard to get good gas and diesel.
Thanks,
98 tigershark

Sorry , I think I used 'Ethanol sensor' in search criteria . Try that , if not I will see if I can find it again .
Oh , watch the country hick comments , not funny !

[98 tigershark]

See My tractor in the background!

[CalEditor]

I will trade you my place in city next to Harley Davidson's R&D head quarters for your place in the NW any time. Then I would be set. My little shack in Rock Hill SC and a place in the Good Old NW. I could actually go visit friend and relatives for a change.