Leafy (Club Jeffie FEA man) wrote:Ok its like we are saying the same thing but I see it a bit differently. Yes we cant tell the PCM to change any of those values and frankly we dont need to (or even want to really). The PCM recognizes stoich as 14.7:1, that's all good for it in its happy little world.
Let me put it this way. If you emptied your tank and put e85 in there right now, here is what would happen. Your car would start and I bet would stall, you may have to right to keep it running a bit for a few minutes. During those few minutes your car is going to be furiously maxing out the fuel trims to achieve what it believes to be 14.7:1 (which if you had a 5 gas analyzer on the tail pipe it would rear an air to fuel ratio of 9.8:1 ish). Ok understand now? That is what happens. Of course you shouldnt driver like that because more likely than not you will pop a bank 1 lean code for maxing out the fuel trims and just barely making it to stoich. Now if the computer thought your injectors were 30% smaller than they actually were...
The computer lives in its own reality with its own set of rules, which dont always have to mesh with whats happening in the real world.
How do you think that analyzer would read 9.8? The car would still be trying t achieve 14.7. And 14.7 on e85 is lean as @!#$. I'm sure you seen that post of that dude with the z that ran e85...... Everything was melted......
The analyzer would read in units of air to fuel ratio. The narrow band reads in units of lambda. Saying that was funny because lambda is a unit-less ratio.
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Hey slo i was just asking becuase i dont know. Thanks for your input. I havent tried it. But if i do ill be sure to make sure i have somone tune my car who knows what their doing. What stand alone sytems are available for the j?
But But but but thats not how narrow bands work.
A life in the day of a narrow band (aka the narrow band decision tree if it was a programmed thing).
Oooo look air with fuel in it.
It touched me.
Hmm is it stoich?
.....No
....................Leaner?
.............................Yes.
..................................... output less than 451 mV based on how much too lean
...............................No, then its rich.
....................................... output more than 451 mV based on how much too rich
......Yes
.....................Output 451mV
Now that doesn't matter what the actual stoich of the fuel is, it will do the same thing. In other words the car could never know that it was running at 14.7:1 or 9.8:1 all it knows is that the narrow band just output 451 mV.
Edited 1 time(s). Last edited Tuesday, June 28, 2011 1:44 PM
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Leafy (Club Jeffie FEA man) wrote:But But but but thats not how narrow bands work.
A life in the day of a narrow band (aka the narrow band decision tree if it was a programmed thing).
Oooo look air with fuel in it.
It touched me.
Hmm is it stoich?
.....No
....................Leaner?
.............................Yes.
..................................... output less than 451 mV based on how much too lean
...............................No, then its rich.
....................................... output more than 451 mV based on how much too rich
......Yes
.....................Output 451mV
Now that doesn't matter what the actual stoich of the fuel is, it will do the same thing. In other words the car could never know that it was running at 14.7:1 or 9.8:1 all it knows is that the narrow band just output 451 mV.
Just swallow your pride already...
P&P Tuning
420.5whp / 359.8wtq
Leafy, i get where you are coming from with respect to the workings of an oxygen sensor, narroband or wideband. They read oxygen concentration and output voltage. I don't think anyone here is arguing that part.
I can tell you from first hand experience, when you use the injector constant to fudge for other changes or variations, the tune will not be as rugged with respect to weather/baro changes as it would if you use the CORRECT injector constant for what is installed. And the bigger the injectors, the worse it will get. By the time you have a big enough injector installed to feed an e85 powered car to any fun/reasonable amount of hp that would require it, and have the constant fudged to "run" e85, your pretty much guaranteed to have to retune every time the weather man tells you to. I can't speak for you or any of the owners for whom you've tuned, but that's unacceptable to me. A summer/winter tune frustrates me.
Along the lines of what Ryan was saying earlier - fudging the MAF calibration on the LNF to run e85 was a weird concept to me as well. You end up with a MAF sensor that reads ~33% higher than it should on a trq based OS. Did people get it to work - yeah they did, but they were ever so relieved when they could do it the right way!
ok oldskool, you can always just increase the ve offset by 30% and fine tune from there. I didnt think of that before because I dont have 30% to play with.
-chris. Stop thinking you are right for just a second and think about it. The computer CANNOT ever command an air to fuel mixture that is not stoichiometric while in closed loop. It does not matter what that stoichometric value is for the fuel in the car nor what the computer thinks that value is. In closed loop its different, and you will have to use your noggin and convert afr to lambda and back to afr based on a e85 scale and then pick the afr you want, convert back to lambda and then convert back to an afr centered around the stoich for gasoline. (which you are still using the wrong one, since modern gas has a stoich of 14.2:1). I know exactly where your argument is coming from and its from not understanding how o2 sensors work and what stoichiometry is. Which is fine, most people don't know how that @!#$ works. Hell I didn't until I took chem 1 in college.
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You can tell some people something, and some people nothing...... Your starting to sound like Bill Hahn's stupid @ss........ YEAH, I went there......
P&P Tuning
420.5whp / 359.8wtq
No major disrespect to any other tuners, but leafy, you have the best ecotec tuner around here telling you it cant be done. He has a VERY successful tuning record, even with the shotty L61 ecu... Im pretty sure he knows what he is doing and talking about.
Hey, I resent that. Sorry chris for making that sound like a personal attack. I sounded exactly like you 3 years ago before I actually understood the inner workings of things. Having a published author of tuning articles and one of the best GM v8 tuners in the country as personal friends was a great help. Let me go look through the WPI motorsports forum archive, I think I should be able to find the posts by Mike OD and Brian Barnhill that talk about a bunch of this stuff. I think the thread there was talking about lean cruise (happened shortly before Mike got lean cruise unlocked for lsx cars in this country).
I cant seem to find it.
I know Ryan understands how this stuff works and that his reason for saying it cant be done is that it cant be done right. You can hack it and make it work but its not right. And I know that Ryan is the best j-body tuner, and I recommend people to him when I can.
But for those of you who think stoich is 14.7, you are wrong. Stoich is the theoretical perfect chemical balance between fuel and oxygen for complete combustion with which only produces water and co2, it also happens to be the air to fuel ratio with gasoline which results in the best mix of fuel economy and emissions. It has a different value for every single difference fuel source.
Lambda is the ratio of actual air to fuel ratio divided by stoich air to fuel ratio. Its 1 for a stoichiometric mixture.
O2 sensors, all of them narrow or wide band actually read lambda, they dont read air to fuel ratios so the computer cannot know what the actual air to fuel ratio is. Just how it relates to whatever the fuel's stoich value is. Most computers keep the o2 data in terms of lambda, however Ryan says that our computer converts it to afr with the assumption that stoich is 14.7:1. Now even if stoich for your fuel isnt 14.7:1 (and its not normal gas these days is 14.2:1) a normal computer doesnt care at all because lambda 1 doesnt change. However in our computers, while it still sees lambda 1 it converts it to 14.7:1. Now, what does this mean? It means that the computer has established that lambda 1 = 14.7 no matter what. Now here's the kicker. Put e85 in the tank. o2 sensor reads lambda 1, tells the computer. The computer converts that value to 14.7:1, now guess what. Your actual air to fuel ratio, if you were to look at it with a 5 gas analyzer, would be 9.8:1. Of course this is assuming that your fuel trims can go to infinity and a lot of other assumptions. Does this make more sense as to where I'm coming from? Chris, there is no way for the car to know what its actual air to fuel ratio is, it can only tell what it is in relation to what the stoichiometric ratio for that fuel is.
Edited 1 time(s). Last edited Tuesday, June 28, 2011 3:46 PM
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Leafy (Club Jeffie FEA man) wrote:I know Ryan understands how this stuff works and that his reason for saying it cant be done is that it cant be done right. You can hack it and make it work but its not right. And I know that Ryan is the best j-body tuner, and I recommend people to him when I can.
Thank you Sir....
Leafy (Club Jeffie FEA man) wrote:But for those of you who think stoich is 14.7, you are wrong. Stoich is the theoretical perfect chemical balance between fuel and oxygen for complete combustion with which only produces water and co2, it also happens to be the air to fuel ratio with gasoline which results in the best mix of fuel economy and emissions. It has a different value for every single difference fuel source.Lambda is the ratio of actual air to fuel ratio divided by stoich air to fuel ratio. Its 1 for a stoichiometric mixture.
I agree with the bold text, however, our PCM does command a stoich of 14.7:1 ...
Leafy (Club Jeffie FEA man) wrote:O2 sensors, all of them narrow or wide band actually read lambda, they dont read air to fuel ratios so the computer cannot know what the actual air to fuel ratio is. Just how it relates to whatever the fuel's stoich value is. Most computers keep the o2 data in terms of lambda, however Ryan says that our computer converts it to afr with the assumption that stoich is 14.7:1. Now even if stoich for your fuel isnt 14.7:1 (and its not normal gas these days is 14.2:1) a normal computer doesnt care at all because lambda 1 doesnt change. However in our computers, while it still sees lambda 1 it converts it to 14.7:1. Now, what does this mean? It means that the computer has established that lambda 1 = 14.7 no matter what. Now here's the kicker. Put e85 in the tank. o2 sensor reads lambda 1, tells the computer. The computer converts that value to 14.7:1, now guess what. Your actual air to fuel ratio, if you were to look at it with a 5 gas analyzer, would be 9.8:1. Of course this is assuming that your fuel trims can go to infinity and a lot of other assumptions. Does this make more sense as to where I'm coming from? Chris, there is no way for the car to know what its actual air to fuel ratio is, it can only tell what it is in relation to what the stoichiometric ratio for that fuel is.
As stated earlier, what does a 5 gas have to do with this? And it won't read 9.8:1, it (along with every other air/fuel ratio sensor) will read what its sensing from the burn......
Have you ever looked at an LSX or LSJ PCM? The pic below is small, but humor me.... Download one, take a look, and then realize what we are missing to make this work.....
Edited 1 time(s). Last edited Tuesday, June 28, 2011 4:18 PM
P&P Tuning
420.5whp / 359.8wtq
Yes ryan. I know. And I know thats why we cant correctly tune for e85. But yes its commanding 14.7:1. But right now with e10 (normal gas) in your car you are idling and you're actually adding 1 unit of fuel for every 14.2 units of air that enters the engine in order to have your computer think that it is running at 14.7. Just like if you put e85 in you would be adding 1 unit of fuel for every 9.8 units of air in order for the computer to think it was running at 14.7.
What does that stoich value do for the pcm? It lets it actually give the right amount of fuel based on the VE map (where as we would have a totally incorrect VE map or a messed up injector constant in order to fake this effect), and it shows you afr cmd values in hp tuners that are centered around that stoich value. 14.7 is just a number.
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QWK LN2 (P&P Tuning) wrote:Leafy (Club Jeffie FEA man) wrote:I still don't know how it can tell its at 14.7 or 9.8, do we use some sort of o2 sensor that I've never heard of? All narrow bands that I've ever heard of can only tell you if the car is running at, not what the actual afr is. Hell, wide bands can't even do that, you need a 5 gas analyzer to do that.
All the O2 sensor does is read the voltage.... They all do the same thing. The PCM is what determines what the voltage value means.... And why are you bringing a 5 gas into this? Like I said earlier, you still have a lot to learn and I applaud you for wanting to learn...
No.
The sensor
outputs a voltage. It reads lambda, which as leafy mentioned is the ratio of actual AFR to stoichiometric AFR.
QWK LN2 (P&P Tuning) wrote: Leafy (Club Jeffie FEA man) wrote:But for those of you who think stoich is 14.7, you are wrong. Stoich is the theoretical perfect chemical balance between fuel and oxygen for complete combustion with which only produces water and co2, it also happens to be the air to fuel ratio with gasoline which results in the best mix of fuel economy and emissions. It has a different value for every single difference fuel source.Lambda is the ratio of actual air to fuel ratio divided by stoich air to fuel ratio. Its 1 for a stoichiometric mixture.
I agree with the bold text, however, our PCM does command a stoich of 14.7:1 ...
As you've stated earlier, the computer commands some voltage (1.00 lambda per the design of the sensor itself). The assumption is made in the programming that 1.00 lambda = 14.7 AFR (i.e. gasoline stoich). So, like he said, if you run 14.7:1 on E85, your sensor (albeit narrowband or wideband) will read lean...but as I mentioned earlier there are certainly serious issues with running E85 that using HPT with a jbody PCM can't account for.
I feel like I'm the only one who has understood what Leafy has been trying to say all along.
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Whalesac wrote:
I feel like I'm the only one who has understood what Leafy has been trying to say all along.
Thank god. I was about to go looking for my engineering experimentation book to re-read the section on air to fuel ratio measurement and experimental stoichiometry to make sure I wasnt crazy.
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Not speaking for anyone else, but I get what he's saying about the O2 sensor and how it works. But I didn't think that was the primary argument here.
I haven't read every word of every thread (lots of redundancy), but i though the primary argument was that there was no correct way in the jbody pcm to globally correct the fueling for the additional mass that is needed with E85 (at stoich, lambda = 1, 9.8:1 AFR or whatever you want to name it). You could fudge the injector constant, or the VE tables, or the IPW vs VAC table or a number of things, but at the end of the day, we really only have a shell of the ENTIRE group of tables/params that is our operating system. I'm certainly NOT saying it CANNOT be done, but honestly i feel no one can recommend a right way to do it.
In anycase, Leafy you would make a more convincing case if you successfully ran E85 year round through a solid four seasons w/o issue.
There are more e85 stations around here but they're all still over an hour away. Once theres enough that its not so far out of the way I'll spend half a tank just driving to get gas I'll do it.
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oldskool wrote:Not speaking for anyone else, but I get what he's saying about the O2 sensor and how it works. But I didn't think that was the primary argument here. I haven't read every word of every thread (lots of redundancy), but i though the primary argument was that there was no correct way in the jbody pcm to globally correct the fueling for the additional mass that is needed with E85 (at stoich, lambda = 1, 9.8:1 AFR or whatever you want to name it). You could fudge the injector constant, or the VE tables, or the IPW vs VAC table or a number of things, but at the end of the day, we really only have a shell of the ENTIRE group of tables/params that is our operating system. I'm certainly NOT saying it CANNOT be done, but honestly i feel no one can recommend a right way to do it.
In anycase, Leafy you would make a more convincing case if you successfully ran E85 year round through a solid four seasons w/o issue.
Iagree.... But be prepared to see a oh snap I melted my ish post from him.
Whalesac wrote:QWK LN2 (P&P Tuning) wrote:Leafy (Club Jeffie FEA man) wrote:I still don't know how it can tell its at 14.7 or 9.8, do we use some sort of o2 sensor that I've never heard of? All narrow bands that I've ever heard of can only tell you if the car is running at, not what the actual afr is. Hell, wide bands can't even do that, you need a 5 gas analyzer to do that.
All the O2 sensor does is read the voltage.... They all do the same thing. The PCM is what determines what the voltage value means.... And why are you bringing a 5 gas into this? Like I said earlier, you still have a lot to learn and I applaud you for wanting to learn...
No.
The sensor outputs a voltage. It reads lambda, which as leafy mentioned is the ratio of actual AFR to stoichiometric AFR.
I mistyped what you put in red..... I agree with this statement...
Whalesac wrote:QWK LN2 (P&P Tuning) wrote: Leafy (Club Jeffie FEA man) wrote:But for those of you who think stoich is 14.7, you are wrong. Stoich is the theoretical perfect chemical balance between fuel and oxygen for complete combustion with which only produces water and co2, it also happens to be the air to fuel ratio with gasoline which results in the best mix of fuel economy and emissions. It has a different value for every single difference fuel source.Lambda is the ratio of actual air to fuel ratio divided by stoich air to fuel ratio. Its 1 for a stoichiometric mixture.
I agree with the bold text, however, our PCM does command a stoich of 14.7:1 ...
As you've stated earlier, the computer commands some voltage (1.00 lambda per the design of the sensor itself). The assumption is made in the programming that 1.00 lambda = 14.7 AFR (i.e. gasoline stoich). So, like he said, if you run 14.7:1 on E85, your sensor (albeit narrowband or wideband) will read lean...but as I mentioned earlier there are certainly serious issues with running E85 that using HPT with a jbody PCM can't account for.
I feel like I'm the only one who has understood what Leafy has been trying to say all along.
And I understand that also..... As Oldskool said, that is not where the disagreement lies.... Leafy is claiming that this can be done. As I stated before ,I am sure it can be done also..... BUT at what risk and reliability? If he wants to have a meltdown on his car, so be it.... But I do not want this type of misguided information being taken by less knowledgable people (who have no business even attempting to tune a vehicle) and them fu(king up their cars....
P&P Tuning
420.5whp / 359.8wtq
Ryan, I stopped arguing with you back when we came to the conclusion that it can be done its just going to be ghetto. The rest was towards chris who still thought it was impossible.
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Leafy (Club Jeffie FEA man) wrote:Ryan, I stopped arguing with you back when we came to the conclusion that it can be done its just going to be ghetto. The rest was towards chris who still thought it was impossible.
Thats kool... I'm not trying to get a pissin match going, and I really do respect you learning this stuff... I really think Chris agrees with what the rest of us are saying... Not putting words in his mouth, but based off what I read, me and him are on the same grounds..
P&P Tuning
420.5whp / 359.8wtq
QWK LN2 (P&P Tuning) wrote:Whalesac wrote:QWK LN2 (P&P Tuning) wrote:Leafy (Club Jeffie FEA man) wrote:I still don't know how it can tell its at 14.7 or 9.8, do we use some sort of o2 sensor that I've never heard of? All narrow bands that I've ever heard of can only tell you if the car is running at, not what the actual afr is. Hell, wide bands can't even do that, you need a 5 gas analyzer to do that.
All the O2 sensor does is read the voltage.... They all do the same thing. The PCM is what determines what the voltage value means.... And why are you bringing a 5 gas into this? Like I said earlier, you still have a lot to learn and I applaud you for wanting to learn...
No.
The sensor outputs a voltage. It reads lambda, which as leafy mentioned is the ratio of actual AFR to stoichiometric AFR.
I mistyped what you put in red..... I agree with this statement...
Whalesac wrote:QWK LN2 (P&P Tuning) wrote: Leafy (Club Jeffie FEA man) wrote:But for those of you who think stoich is 14.7, you are wrong. Stoich is the theoretical perfect chemical balance between fuel and oxygen for complete combustion with which only produces water and co2, it also happens to be the air to fuel ratio with gasoline which results in the best mix of fuel economy and emissions. It has a different value for every single difference fuel source.Lambda is the ratio of actual air to fuel ratio divided by stoich air to fuel ratio. Its 1 for a stoichiometric mixture.
I agree with the bold text, however, our PCM does command a stoich of 14.7:1 ...
As you've stated earlier, the computer commands some voltage (1.00 lambda per the design of the sensor itself). The assumption is made in the programming that 1.00 lambda = 14.7 AFR (i.e. gasoline stoich). So, like he said, if you run 14.7:1 on E85, your sensor (albeit narrowband or wideband) will read lean...but as I mentioned earlier there are certainly serious issues with running E85 that using HPT with a jbody PCM can't account for.
I feel like I'm the only one who has understood what Leafy has been trying to say all along.
And I understand that also..... As Oldskool said, that is not where the disagreement lies.... Leafy is claiming that this can be done. As I stated before ,I am sure it can be done also..... BUT at what risk and reliability? If he wants to have a meltdown on his car, so be it.... But I do not want this type of misguided information being taken by less knowledgable people (who have no business even attempting to tune a vehicle) and them fu(king up their cars....
I'm glad we are now all in agreement
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That cool. I mean any of us who can tune one of these damnable things for boost and have it last over a year is doing something right. I mean @!#$, I still dont like this tune and I've been working on it for a year on an off. Sure I havent touched anything to change the amount of power it makes since the first month, I want more gas mileage, 30 is not enough, there's more to be had. And it really killed me with that racecar on haltech. I went from a map that was based 100% on math from an excel file to a nearly max power tune in an hour and a half on the dyno, made extra hard by the fact the car had an intake restrictor, barrel throttle body, and cvt.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
