using 14.047 for desired AFR and not 14.63?

Before reading or responding please note the ? at the end. When we buy gas today it is very difficult to stay away from 10% ethanol. When setting up our tune we use an AFR as 14.63 approx for the most part and 1 for lambda and EQ. But what is the correct Base AFR to use with the fuel in the market today.
AFR is based on 14.63 part of air to 1 part of fuel. But when you do the math with 10% ethanol it seems way off to me. So I did just a little math for an open discussion and input. 10% ethanol has a correct AFR of 8.8 to 1, I think.
so since the fuel in general has 10% ethanol and the AFR for that is 8.8 approx I used the following formula. (14.63x90%) = 13.167+(8.8x10%)=14.077 or (14.63x9=131.67)+(8.8x1=8.8)=140.47/10=14.047AFR. Is 14.047 AFR or 14.077AFR the correct base to use for AFR with todays gas? If so what does this do to EQ and Lambda?. This seems correct to me so does anyone know what the adjustment should be?
Thanks in advance,
98 tigershark :throw::crash::nixweiss::blahblah:

open up a flex fuel cal from a truck, for 10% ethonal in the fuel that is the proper afr 14.07. Most cars are set 14.63 for regular gas obviously and then the computer will compensate for the 10% ethonal via the stft and ltft which is what I was lead to understand from the info I have been reading.

That is my understanding also. But if the trims are trying to adjust (learn) to 14.63, it would seem that the PCM is learning to make the car run lean. Enough to make the LTFT off by quit a bit it would seem. The reason I brought this up is there is another members post on the forum who is having LTFT trims off by as much as 20%. If it is not a bad fuel filter or intake/exhaust leak it seems to me it could be the fuel he gets has changed to cause this.
Thanx,
98 tigershark

I believe the narrow bands will adjust to stoich of whatever the AFR is of the fuel your running. So if pure gasoline they will adjust to stoich which is 14.68 and if E10 14.07 being stoich is stoich and the sensors don't know the type of fuel your running.

Correct. The NBO2's will report back to the PCM that there is a lean condition and then the PCM will increase fuel trims to richen up the mixture. In essence, the car should "learn" at cruise and transfer additional fueling requirements to WOT. Those who are running in open loop will need to adjust their tune manually.

In {B3601} can we use 14.07 and be Ok with the trims or is it the EQ that is the deal here? There is not one Gas station I am aware of in close range of were I live that sells Gas without 10% ethanol.
98 tigershark

Subscribing!!!

Jeff

If you use Lambda in your PE table {B3618} then it will look up your {B3601} and compute the desired fueling based upon your entered value in {B3601}.

For example say you command .88 lambda for your PE table {B3618} and use 14.68 for {B3601}, your commanded fuel would be 12.91 now if you change your {B3601} to 14.07 and the same .88 lambda for {B3618} you would be commanding 12.38 instead.

Using lambda .88 keeps the fueling consistent at 12% richer than stoich for WOT depending on the fuel you run and your value in {B3601}

Greg aka "eficalibrator" could probably clarify it better than I though

Hey SSpdDmon,

I am not trying to be difficult but I cant seem to get my brain around this.
The NBO2 sensor will detect a lean condition because there is one, that I get. but why not just use the 14.07 in the 97-04 PCMs B3601. That would mean that 14.07 is stoich for those PCms then if that is the fuel ie. 10% ethanol? Right? or wrong? Help anyone, help!:help2:
98 tigershark

Quote:

---

Originally Posted by SSpdDmon

Correct. The NBO2's will report back to the PCM that there is a lean condition and then the PCM will increase fuel trims to richen up the mixture. In essence, the car should "learn" at cruise and transfer additional fueling requirements to WOT. Those who are running in open loop will need to adjust their tune manually.

---

It would be an easy test 98 tigershark.
Compare the commanded AFR in a log with 14.63 in B3601 to a log with 14.07 in B3601.
Since the computer thinks in EQ, changing this calibration should cause a change in commanded AFR.