e85 tables

[Corysvdub]

Was curious if anyone had an e85 Afr table they were willing to share? If you have a timing table to share as well, that is welcomed too.

Thanks guys

[Piledriver]

Was curious if anyone had an e85 Afr table they were willing to share? If you have a timing table to share as well, that is welcomed too.

Thanks guys

Have you considered just adjusting reqfuel and using your existing VE table as a base?

Should be able to find an appropriate regfuel setting via the WBO2, that's essentially how GM currently does flex fuel.

The VE table will shift some due to E85s cooling effects, but not that much.

The AFR table will need reworked though, unless you had everything set up using lambda instead of AFR.
(IIRC lambda will eventually be used for all calculations, and translated for AFR display if desired, probably in next major FW rev)

You should be able to simple shift it by the same % as reqfuel.

[Corysvdub]

Thanks Pile,

I thought I had to increase my target afrs on e85?

[foreverska]

Well what pile suggested kinda takes the place of the adjusted target AFR table. E85 is (for the most part) predictably leaner than gasoline. So if you crank up your REQ_FUEL when it aims for 14.7 it will actually be aiming for E85 AFR. I can't imagine this should be done with any sort of correction in place though. I'm surprised trims don't go bat poop crazy trying to bring the actual AFR back to E10 levels. But I will defer that to Pile because I'm definitely no expert.

This table shows a comparison between Gasoline and E85. While I cannot verify it's information it might help you if you decided to go the target AFR route. It seems to be close in it's stoich numbers with other sources if that makes you more comfortable.
http://i621.photobucket.com/albums/tt29 ... achart.jpg

[ps2375]

Or you could lower the afr targets by 30-35% and add the same 30-35% to VE table, then re-tune. If you have knock sensing, adjust timing and re-tune some more.

The only real advantage to e85 is with boosted/high CR motors. Your average motor will just use more fuel and most likely run cooler. Just saw your sig, more boost and more timing. Have fun.

[foreverska]

Wait.. why would you shift the VE table up 30%? You aren't fitting that much more air into the cylinder. If he's going to edit the AFR table he just need to edit the AFR table and maybe some VE adjustments for cooling effects like Pile said but not 30%.

[Piledriver]

Hopefully someone currently running E85 will speak up...

I was very tempted to try it myself tonight, new gas station ~1/2 way to work has an E85 nozzle at all 12 double sided pumps... No laptop today.

This may or may not be obvious: (I had to process on it some, Google wasn't much help due to many confusing and sometimes wrong posts on the subject)

I'll take a shot at a simple explanation:
When the lambda picked up by most WBO2 (that translate it internally to gasoline AFR) reads 14.7:1 it will read exactly 14.7 at stoich, regardless of fuel, the WBO2 cannot detect the fuel, just the lambda, and most are programmed to translate lambda to AFR for gasoline...

Lambda is what is measured. Gasoline AFR is what is (usually) displayed.
...Thus your existing (translated) AFR table is probably a very reasonable starting place for E85, at least at ~stoich and leaner, esp as E85 is supposedly more forgiving (wider flammability range)
What I'm not that sure of is the actual effective range of most WBO2s on E85 rich of stoich.
The common Bosch LSU 4.2 sensor has its limitations.

My current dd motor isn't ideal for E85 CR wise, but the 240cc injectors should be sufficient for a 1.8L bus motor with really good heads. (I can't even make it knock with 30 degrees extra timing on regular at 100+F air temps)

I suppose one could also just tweak reqfuel so that it simply matches "AFR" reasonably a few spots on the map.
IIRC current GM procedure mainly does it at idle, possibly using a NBO2.

The limits on the installed WB also limit what you can target for AFR, at least on MS3.
(I cannot set over 20:1 if the WB upper limit setting is 20:1.)

I want to see how that works out in meatspace.
I think I can set my old JAW to put out lambda directly...

[Chip Birks]

When i ran e85 i ran the same afr targets for the reasons specified by Pile. Worked just fine. I speak "gasoline" much better than trying to convert for e85.

[ps2375]

Now that I think about it, Pile is correct about the WB readings, it just reads stoich and converts that to "afr" for us. So, if you ran off of the same AFR target table, and tuned from that, My guess is the VE table would richen up by about 30%. Remember, the "VE" table is actually a conversion of how much fuel in pulse width that is being delivered. With e85 you are not actually getting more air in the cylinder, but you are delivering much more fuel to it, remember to reach "stoich" with e85, it take more fuel. So, I was wrong to say to lower the AFR target table, since w/o a MAF, we have no way of measuring actual "air mass" being taken in by the motor, MS just measures "load" via MAP sensor and "burn" via WB, or lambda(which is not the same as AFR).

[foreverska]

Remember, the "VE" table is actually a conversion of how much fuel in pulse width that is being delivered.

No it isn't and that's a dangerous way of thinking about it. Yes raising the VE table will richen up your mixture but that is only because the equation now thinks there is more air.

VE stands for Volumetric Efficiency:
Volumetric efficiency in the internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the cylinders. More specifically, volumetric efficiency is a ratio (or percentage) of the quantity of air that is trapped by the cylinder during induction over the swept volume of the cylinder under static conditions. (Wikipedia)

With e85 you are not actually getting more air in the cylinder, but you are delivering much more fuel to it, remember to reach "stoich" with e85, it take more fuel.

This is true and why the AFR should be adjusted not the VE. The ECU is looking at how much air is in the cylinders and then using the AFR to calculate how much fuel belongs in there with it. Now I'm not super well versed on the internals of MS so when people say MS reads lambda and then converts to AFR that is something I did not know. It also concerns me because that would indeed make it read 14.7 at stoich for E85 BUT the calculator when it is doing it's math is still using the number 14.7 in it's REQ_FUEL calculations if you leave it where it is which wont really cut it on E85. So you need to adjust AFRs but you CANNOT use that table in the autotuner or else it will constantly think it's lean. Now if there is lambda table for the autotuner...

The most graceful way to handle this (and I don't know what your MS is capable of) is an ethanol sensor tied to a table which richens the mixture based on E rating. Some domestics do it this way... Ford Explorer maybe. Then your E10 AFR table will make a good stand in until you can adjust it for the richer parts.

Alternatively find a way to jack up your REQ_FUEL artifically, lower your injector flow or or somthing like that. But that is sort of a hack job way of doing it.

[subwoofer]

Actually, adjusting REQ_FUEL is the correct way to do it! Since the WB actually reads 14.7 at stoich no matter what fuel - or whatever arbitrary value you choose for stoich AFR - you want req_fuel to be the pulse width that causes a full cylinder of air at nominal 1 atmosphere Baro pressure to burn stoichiometrically (sp?).

With the advent of a variety of alcohol mixes, and even the variance from one batch of e85 to the next, lambda is really the only measurement that makes any sense at all.

[foreverska]

Well jacking with a static of your REQ_FUEL is hardly the "correct" way of doing it but it will achieve the desired result.

The trouble with lamda is it can mean anything. To find out how much fuel goes into the mixture the ECU needs to know a target AFR and lambda simply doesn't tell it that. But lambda is correct for automatic correction and trim. You're right about the alchol mixes and I think that's why OEMs here in the states went with ethanol sensors on their Flex Fuel vehicles.

[subwoofer]

Au contraire, lambda is well defined, AFR is all over the place. Think of the AFR as lambda x 14.7 and leave all calibrations as is, then adjust req_fuel until you match the AFR you had on gasoline.

[Devastator]

The tables I sent you didn't help?
To tune mine, I programmed the WBO2 to "see" E85 stoich at 14.7, so I could use fuel tables for gasoline. Works like a charm.

[squeakie]

To tune mine, I programmed the WBO2 to "see" E85 stoich at 14.7, so I could use fuel tables for gasoline. Works like a charm.

Where should I start looking to do this to my setup?