using 14.047 for desired AFR and not 14.63?

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Originally Posted by 5.7ute

No, what I am saying is an error in B3601 will bring errors into AutoVE if commanding away from stoich.
An easy example would be like this.
lets say cylinder airmass is 0.62 G/cyl. commanded afr is 1.14 EQ and the IFR is 5.0 G/sec. Offsets we will leave at 0 for simplicity
B3601 set to 14.63

IBPW = 0.62/(14.63/1.14)/5.0
IBPW = 0.0096623 sec

B3601 set to 14.04

IBPW = 0.62/(14.04/1.14)/5.0
IBPW = 0.0100683 sec
A difference of 0.000406 sec or near 1/2 m/sec in commanded pulsewidth.
I havent fully worked this out yet & could be chasing shadows or just plain overcomplicating things. Time to fire up excel & do a little math.:doh2:

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Yes, a drop in B3601 will increase injector pulse width because you're telling the PCM the stoich AFR of the fuel you're using is richer. So, it almost goes without saying that the injectors will need to stay open longer. That's why it's important to understand what you're putting in your tank.

For me, I thought I was doing a great thing going to Sunoco and getting 94 octane gas...until I noticed it has a higher octane rating partly because it's 10% ethanol. http://www.motownmuscle.com/forums/i...lies/swear.gif

Hello Greg,

Thanks for the input as it is nice to have you in on this thread. I dont think there is the resistance to EQ that you think. I personally need to understand the fuel. In EFILive you do have to put in an AFR in B3601 and some of the tuners (me) use by default the 14.63 or 14.7. There have been many excelent posts put up such as 5.7ute, SSpdDmon, mr.prick and yours. This is an exelent teaching/learning issue and I for one am the student. Fuels are changing as we all know and I am really looking forward to the help in translating my tune to EQ not because of I like AFR better but it was easy and worked. Now that the fuel I can get locally for my car has changed for ever, I wanted to learn what this meant and how to adapt my EFIlive tune to EQ but mostly for the ever changing fuel and in this case 10% ethanol and maybe even E85. Did you see the http://www.e85mustangs.com/regions123.html posted by SSpdDmon. That was a real eye opener. I do think this is more about learning for me it sure is. The IBPW issue is a good example. It would be nice to have someone like yourself explain the Big changes one must employ to use E85 and to expect much worse milage and how to pass all the EPA issues with these fuels.
Thanking you in advance as this has really taught me allot and I appreciate all the input very very much. Please keep in mind that we EFILive users do have to put in an AFR value in B3601 so I need to learn what that means all the way around with fuel and the tune.
Thanks for all the input from the guys on this thread or post and I am really looking forward to learning more.
Thanks all,
98 tigershark

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Originally Posted by eficalibrator

Guys, I just don't understand the resistance to using either lambda or EQR. I know you've been conditioned to see gasoline AFRs all along, but it's time to move on. You're only causing yourselves more unnecessary headaches.

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I had injectors that were borderline for my motor. Now that I can pretty much only get 80-90% gas with 10-20% ethanol it in all likely hood that has put my injector duty cycles past the safe percent 80% and I do go to 90% when racing a few times a year. It takes more fuel and IBPW's with ethanol in the mix to hit the targeted air to fuel ratio whether tuning with AFR,EQ or LAMBDA.
In the case of E85 I have heard it cuts the gas milage in almost half. I have heard the AFR for E85 is 8.8 to 1. That is almost double the duty cycle for the injectors to hit the desired ratios. Is this correct????
98 tigershark

I thought I would call GMPP to find out what they do. This is what I was told;
E10=13.81 AFR
E20+11.21 AFR

I took notes all they way down the line and cannot read my writing for the rest, Sorry! Also for their flex fuel vehicles they use a Composition sensor to determine the amount of alcohol in the fuel. And the computer does the rest. SSpdDmon was right when he said we might as well have a PID for the various types of ethanol fuel for the WBO2 sensors (ie his post)
It is important to make the correct adjustments. Another point was that one needs to be careful as to the fuel that you might mix (not knowingly or intentional), in other words from Gas to E*.* and Gas, as some Gas does not have the correct ingredients to mix them. So if I went to get gas in Portland and I have a 1/4 tank of E10 i need to be careful. I dont really know what I can do about that but the difference between E10 (13.81 AFR) and regular gas (14.7 AFR) is more than a little. So you still do need to know the AFR in order to get the right EQ and or LAMBDA. Once you know the correct AFR of the fuel in your tank, you can then tune with what ever you prefer. I wonder if there is a simple sensor we could buy to check the % of ethanol that we put in our tanks?
98 tigershark

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Originally Posted by 98 tigershark

I thought I would call GMPP to find out what they do. This is what I was told;
E10=13.81 AFR
E20+11.21 AFR

I took notes all they way down the line and cannot read my writing for the rest, Sorry! Also for their flex fuel vehicles they use a Composition sensor to determine the amount of alcohol in the fuel. And the computer does the rest. SSpdDmon was right when he said we might as well have a PID for the various types of ethanol fuel for the WBO2 sensors (ie his post)
It is important to make the correct adjustments. Another point was that one needs to be careful as to the fuel that you might mix (not knowingly or intentional), in other words from Gas to E*.* and Gas, as some Gas does not have the correct ingredients to mix them. So if I went to get gas in Portland and I have a 1/4 tank of E10 i need to be careful. I dont really know what I can do about that but the difference between E10 (13.81 AFR) and regular gas (14.7 AFR) is more than a little. So you still do need to know the AFR in order to get the right EQ and or LAMBDA. Once you know the correct AFR of the fuel in your tank, you can then tune with what ever you prefer. I wonder if there is a simple sensor we could buy to check the % of ethanol that we put in our tanks?
98 tigershark

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Thats interesting Tigershark. They go a little over the expected numbers.

We run 9.8 here for E85, and depending on the calculated (pen and paper LOL) E mix, adjust stoich AFR in the ECM accordingly.

The GM Ethanol sensor is around 400 bucks. It generates a frequency based output based on the conductivity of the fuel.

Ethanol apparently being "1 million times"* more conductive than gasoline there is a considerable variation.

GM also uses a virtual fuel sensing setup which simply and smartly figures out the approximate mix via the O2 sensors and some software wizardry, though there have been reports that this is not reliable all the time.

We actually do have an ethanol sensor in our cars already. The PCM coupled with the O2 sensors can be used to "indicate" ethanol content and work out required AFR.

How? You log your LTFT's on your tank of gas. You know where they are then. Say they are within +/- 3. You fill up with whatever. All of a sudden your LTFT's move by 8 points up or down. Or if you go from an empty tank of straight gas to a full tank of E85 for example, the LTFT's will go to 25% reasonably soon. 25% because they generally top out in a stock tune at 1.25 rich. So you change the limit to 50% and they will probably settle at around 40-45.

Then calculate your stoich AFR from there and reflash the PCM. Might take a few shots as you home in on getting LTFT's back toward zero again. Last tank of E10 here pushed the LTFT's to around 10 points rich.

Will this work with every OS/tune? Dont know. But it works ok here on E38/E67's.

There are risks of course. Check it out incrementally.

* Source: Chrysler engineer.

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Originally Posted by eficalibrator

Guys, I just don't understand the resistance to using either lambda or EQR. I know you've been conditioned to see gasoline AFRs all along, but it's time to move on. You're only causing yourselves more unnecessary headaches.

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Greg, it is not a resistance to using EQ or lambda. It is a question of accuracy.
For instance, when tuning the VE table using a custom operating system, we must command away from an EQ ratio of 1.0 to prevent STFT from occuring. If B3601 is incorrect for the fuel being used our airmass calculation will have errors. While it may be splitting hairs it is no different from having incorrect injector data in your tune.
After all, isnt tuning about having the tables accurately reflecting the hardware & conditions.

Thanks 5.7ute,
That is the real issue. You simply can not use EQ or Lambda for B3601 with EFILive (I do not know about HP or LS1 edit as I havent had that ever since I bought EFILive). It can inly be entered in AFR and it needs to be accurate. I am glad that Greg has gotten involved in this topic and am looking forward to his input. But with EFILive you do have to input an AFR in B3601 only as you cant use EQ or Lambda. The program wont let you. Have you looked at the program?
I do use EQ also but, need to learn what is the stoich for the EQ of 1 with the fuel and also the AFR for the program (B3601)
Also thanks GM308 that is very interesting. I have a case # with GMPP and they are great guys and always helpful. I too was a little surprised at the AFR for E10 as I thought we had the correct formula. The conductivity is also a very interesting point. Thanks GM308.
98 tigershark
PS 5.7, I had to chuckle about the race fuel (110 oct) as I did the same thing.

Quote:

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Originally Posted by 5.7ute

Greg, it is not a resistance to using EQ or lambda. It is a question of accuracy.
For instance, when tuning the VE table using a custom operating system, we must command away from an EQ ratio of 1.0 to prevent STFT from occuring. If B3601 is incorrect for the fuel being used our airmass calculation will have errors. While it may be splitting hairs it is no different from having incorrect injector data in your tune.
After all, isnt tuning about having the tables accurately reflecting the hardware & conditions.

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Also for open loop operation with the default OL tables, the PCM/ECM must be told what fuel it is running by setting the AFR at stoich. In closed loop it can figure this out by itself.

We work only off a lambda base at all other times. It makes life so much easier.

98 tigershark. B3601 has to be calibrated in AFR as the PCM needs to know how much fuel to inject.
Going off the last equation where
cylinder airmass is is 0.62 G/cyl
commanded EQ is 1.14
{B3601 is 14.63 &
IFR is 5.0 G/sec
What happens first is the PCM calculates the amount of air in the cylinder. In this case 0.62 grams. It will look up {B3601} which it will then divide by the commanded EQ ratio. 14.63/1.14 = 12.83333. Cylinder airmass is divided by this number to calculate how much fuel needs to be injected in grams.
0.62/12.83333 = 0.0483116 grams of fuel
The sum of these values is then divided by the IFR 5.0 g/sec to give the pulsewidth necessary to inject that amount of fuel.
0.0483116/5.0 = 0.00966233 seconds or 9.66233ms.
Hope this clears things up.

For the record, I like all the methods of tuning EQ, LAmbda and using AFR only when I have too But I appreciate the help with this as it has really shed light on the fuel issues today and has taught me to be more aware of what I put in my tank and the accuracy issues. I am still a little unclear on how to set up the WBO2 sensor PID and programming it though with the E fuels.
98 tigershark