Hey guys, im working on a tune on my car for e85, i understand that stoich is 9.765. What AFR should i shoot for during WOT?
Hey guys, im working on a tune on my car for e85, i understand that stoich is 9.765. What AFR should i shoot for during WOT?
anybody?
Leave it on gas settings because both gasoline and e85 have the lambda ratio of 1:1. Its a lot easier this way and they are familiar ratios. Just put e85 in and pretend your tuning pump gas ratios.
E-85 279.5whp/258tq
What do you mean by that? Like keep the stoich value at 14.7? Or leave the PE the same?Originally Posted by skatinboarding
Keep the stoich value the same. Here is a very good thread about it. Lots of good info.
http://www.redlineforums.com/forums/...o-results.html
E-85 279.5whp/258tq
Thanks bro.
Anytime E85 FTW.
E-85 279.5whp/258tq
Yeah and watch your trims max positive quick smart.
If you run an ethanol based fuel.. You MUST alter the Stoich value to suit. PE tuning in Lambda is very similar though, if anything you can run a little leaner.
Both gas AND ethanol have the lambda ration of 1:1. So if you have 50% gas and 50% ethanol the ratio is still 1:1. If you have e10 its still 1:1. If you have 37% ethanol and 63% gas its still a ratio of 1:1. Do not tell anyone to run their car leaner.
If someone wants to go through the hassle of changing their fuel settings for e85 be my guest and waste a good chunk of time that is going to be the same thing, but just read in unfamiliar digits.
On a side note are you tuned for e85?
E-85 279.5whp/258tq
Buddy you are so misinformed its not funny and someone will blow an engine up if they take what your saying as gospel.
To explain it a little further the PCM actually works with EQ (the inverse of Lambda) but that's not the point. The point is the PCM doesn't know what fuel your running. It knows what fuel it thinks its running via the stoichiometric ratio value set in the tune. The PCM will reference the stoich value and then use the commanded EQ ratio and divide it into the reference value (14.7 for gas) and give the AFR. eg Stoich 14.7 / EQ 1.14 = 12.9AFR. If you use E85 and don't alter the stoich value to 9.76. You will still inject 12.9AFR for the same EQ ratio, which is way to lean for E85
From the commanded AFR the PCM calculates how long to open the injector (IPW) by computing the airflow model/MAF with the Injector Flow Rate to provide that AFR.
In the end all the PCM cares about is how long to open an injector for. Lambda values, EQ ratios mean nothing to a PCM. E85 and Gas have different stoich ratios. If you don't tell the PCM about it then its not going to do anything about it, except when it comes to o2 feedback trims later to which as I explained before will max out when you need approx 40% more fuel to obtain stoich for E85.
You know what your talking about and it makes sense if the lambda ratios were different values on gas and ethanol, but they are not. Im not going to fight with you because I have had a lot of experience now with ethanol. Here is an example that I have done and it worked,
So you say that You NEED to change your stoich value or it wont run correctly. Now I am tuned for e85 and I leave my stoich value at 14.7 just for the convenience that I am familiar with these numbers. Everything is running spot on mind you, fuel trims are perfect and maf is right on. So I change my w/b to read ethanol stoich values and wa-la its 9.76. The rear o2 sensor IIRC will read lambda and convert it to the stoich value you have it set for, there for since its the same lambda it will come out the same no matter what (when the two liquids have the same lambda).
You didnt answer my question, are you tuned for e85? How many hours do you have working with cars converted to e85?
E-85 279.5whp/258tq
Are you comparing a PCM stoich of 14.7:1 against 9.76:1 stoich from WBO2?
If so you should be tuning a skateboard and not a car.
Your WBO2 stoich should match the PCM stoich.
No my wide band is reading gas stoich but Im just trying to explain that it is the same thing using an example. Maybe it was a bad example but im trying to explain that BOTH ethanol and gasoline have the SAME lambda ratio. How many times do I have to say that. Please tell me whats so hard to understand this. Would you guys like me to load a log of my car running e85 still using the gasoline stoich values in the tune so you can see what im talking about? The stock 02 sensor reads trims off of lambda so its going to run correctly.
Im a pretty easy going guy and I know what Im talking about with e85. Done a lot of research and reading and trial and error. I have gotten a lot advise from other e85 converts and they are all doing the same thing. There is a reason why dyno shops keep their w/b reading gas ratios (with e85 cars) when on the rollers unless you specify you want them to switch.
If you would like me to tune your skateboard let me know, I think i have some new bearings I could put in for you. haha
Last edited by skatinboarding; 05-11-2010 at 10:12 AM.
E-85 279.5whp/258tq
Ok so how the hell does the PCM know to inject 30-40% more fuel if it still thinks the fuel your running has a stoichiometric value of 14.7:1?
You keep saying that both fuels have the same 1:1 lambda ratio. That's a nonsense description anyway as lambda isn't a constant ratio for starters, nor really a ratio at all for how your portraying it, so get that out of your head. 1.0 Lambda represents complete combustion of all the fuel (I hope you can accept that as it's the most basic tuning lesson there is). If there is residual oxygen then its leaner than 1.0. If there is residual hydrocarbons then its richer than 1.0. That is all an o2 ever does end of story. Ethanol fuels are oxygen enriched by nature. That why the stoich value is lower as you need more fuel to obtain complete combustion.
The actual volume of fuel and air lambda couldn't care less about. It just knows if everything is burnt or not and to what degree if its not. But the PCM sure as hell cares as it needs to know the volumes of both to regulate fuel delivery compared to the air allowed to enter the combustion chamber. Hence it needs to know the stoich value of the fuel to do that. After all the o2's have no idea what the stoich AFR is.
Last edited by macca_779; 05-11-2010 at 11:04 AM.
I see what you mean.
It still doesn't make any sense to use gas #'s when using another fuel.
If you ever change to gas everything will be off.
Obviously that's not a problem if you stay with E85 but
the stoich AFR value is there so you can change fuels without having to re-do MAF/VE ect.
I assumed you knew that I recalibrate the maf for the 30% more fuel.
E-85 279.5whp/258tq
I use the gas #s just because I am familiar with them. Like I stated in my last post I assumed we all knew the maf/ve had to be rescaled. I was just trying to state that stoich ratios will be relevant with ethanol and gasoline.
Edit and I want to add that in the link that I gave the OP it states that the maf will have to be scaled to the more fuel needed. When He said thanks I figured he read through it.
Last edited by skatinboarding; 05-11-2010 at 11:18 AM.
E-85 279.5whp/258tq
Why would you assume that? That's an incredibly random thing to do as now your dynamics will be totally out as your VE is not matched to the fudged MAF scale. Why would you lie to the controller about the air charge either? Its the fuel that's changed. Not the air.
I also fail to see how this is easier or even logical as all you would have had to do was change the stoichiometric value in the tune and not (theoretically) touched anything else.
[Edit] I noticed you may have also fudged your VE to resolve the change in fuel. While that will account for the errors in fuelling in an arse about manner. What about the other aspects the controller uses air calculations for. ie Idle. 30% more air is going to reek havoc with your drivability.
I don't understand what your familiarity with gas #'s is that is so important.. Its not like your using EFI LIVE where you can command fuel in AFR #'s. Your using EQ which as I've already explained has nothing to do with AFR.
Last edited by macca_779; 05-11-2010 at 11:41 AM.
Alright, The first post you qouted of mine had the link in it. The link has the information that I assumed you knew because i thought you might have read a bit of it. Here are the steps of my convert to e85 went.
Ran out of gas.
Filled up with e85.
Changed to 80lb injectors and flashed the injector data to my car.
Scaled my maf table for idle all the way through wot. (I have my ve tables disabled)
I know the op from another forum and I know he knows how to tune ve/maf tables in. I was just lending a helping hand for him to keep things simplier.
And you still havent answered my question, how much ethanol experience do you have.
E-85 279.5whp/258tq
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