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Old 03-19-2006, 04:03 AM   #251
hotrod
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Hey Gary - sounds like a good excuse to go to the next level of development.

While on the topic a note for everyone monitoring this thread. I am in the process of doing some winter modifications on the car, and that includes doing a fuel system upgrade. I recently pulled the stock fuel system out of the engine compartment and cut a segment of the OEM fuel hose lengthwise to examine how it was holding up to high ethanol fuel blends.

With the hose still wet with fuel, I cut it lengthwise and opened it up, the interior of the hose was slick and clean and looked like a new fuel hose. I then bent it back on itself 180* to look for any signs of checking or cracking. The hose was completely free of cracks or signs of swelling and pliability was normal. I also checked the O-rings on the injectors. They likewise looked perfect, with all the softness and flexibility you would expect from a new O-ring.

Today I went back and looked at the fuel hose segment (it has been drying for over a week now) and repeated the bend back test. It still is perfectly clean, flexible and free of any signs of deterioration on the interior of the hose. I would have no qualms about putting this hose back in service if it wasn't for the lengthwise slit I had to put in it to see the interior of the hose.

In short the OEM rubber fuel lines used by Subaru seem to be 100% compatible with high ethanol fuel blends, based on almost 2 years of exposure. Total alcohol consumption over that period of testing was in excess of 500 gallons.

Larry
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Old 03-19-2006, 09:23 AM   #252
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you were still using the stock o-rings for the injectors? or the one originally suggested for ethanol mixes?
So basically everything in our fuel system is fine except the pump, and thats the only thing we need to change?
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Old 03-19-2006, 04:15 PM   #253
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Kax, you're almost right. I agree more with larry that slightly larger injectors are all that's really needed. The pump is a worthy upgrade, too. I just wanted to see how long I could stress the hell out of it before it croaked. We'll see if the stock fuel pump hates it or not with new injectors. I won't be doubling the pressures on this pump because I'm almost positive it will fail much quicker. I still think a new pump is a worthy upgrade, though. The most important thing with tuning ethanol is getting the richer mixture into the combustion chamber. A more PC route to that is installing bigger injectors. My worry with doing that on the stock pump is that the pressures will be too low and the car will hesitate. I really believe E85 is a "lucky pot o' gold" for Subaru tuners. Infrastructure aside, the fuel itself works great in our cars! We just needed a fuel that didn't detonate in our cars like standard squirrel-piss gas. Crank up the boost, pour in the fuel, and off we go!
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Old 03-19-2006, 04:29 PM   #254
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if we upgrade the turbo, and base the injector size off that, would we still need to go bigger just for e85? for example, i have 600cc injectors on a vf22, the 600s seem to be the perfect size for the turbo. would i need to get bigger injectors then the 600s to run the e85 on my setup? or is it that they just need to be bigger then stock?
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Old 03-19-2006, 09:07 PM   #255
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A vf22 and 600's should do fine I would think. You may want to back off the boost JUST a tad if you're at 18psi or something like that. Drop to 14-16psi and inch up from there. I think your combo would do fine. If you were still on the stock 440's you might have problems. Just watch your injector duty cycle and don't over work them. Part of debunking the myths is that this stuff still tunes very similar to gas.
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Old 03-19-2006, 09:42 PM   #256
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problem is its Ecutek'd at 19 psi, so unless i get a mbc (which i dont really want to do) i cant turn down the boost. should i try and get it retuned for e85 before trying it out?
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Old 03-19-2006, 10:49 PM   #257
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hmmm...well. Find out what your injector duty cycle is for the setup you're running. I'd use a scan tool or at the very least find out what it might be for someone else with your same mods and map tune. If the injectors aren't being worked that hard, which I think they aren't, you should be fine. If you're only at 50%-60% cycle at full boost or at redline, try a 50/50 mix of gas and E85 and compare the duty cycle numbers.
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Old 03-19-2006, 10:51 PM   #258
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will do, ill call the tuner sometime and see if he remembers or can look up my numbers from his tune. I still have to wait for a station to open in FL, so no rush.
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Old 03-20-2006, 01:13 PM   #259
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Just put a half-tank of 100% E-85 into my `06 STi. The thing is stock, except for an APS short ram air intake the guy that owned the car before me put on it. I bought the car at 2400 miles.

After about an hour of $hit-canning the thing on the E-85, I got a CEL and a blinking cruise control light. According to every piece of information I can find on it, this light combo indicates the car put itself into limp-mode (safe-mode).

Anyone else seen this from an E-85 fuel swap? Apparently "safe mode" can be triggered by any number of things (most of which amount to any of your sensors getting a questionable reading or malfunctioning)

I am going to check all the hoses and electric connections just incase I knocked something loose from bombing around... just wondering if anyone has seen this?

Also, does anyone know if "safe mode" will clear itself, if whatever it's problem is comes back within acceptable limits (assuming it's a sensor reading it doesn't like caused by the E-85) or if I have to have the mode cleared at the dealership?
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Old 03-20-2006, 01:17 PM   #260
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you shouldnt drive you car hard after just putting in the e85, you need to let the ECU learn it for a little while, or else those things will happen. as to when it gets fixed, put regular gas into it and it should go away after a little while. as posted before in this FAQ, you need to kinda break in the car to the e85 before you go speeding around everywhere.
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Old 03-20-2006, 01:21 PM   #261
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^^^bingo. Reset the ECU and see if it goes away. Hopefully you didn't hurt anything. But, you're just supposed to cycle through normal driving for about 50 miles--cruise and stomp it occasionally. The idea is to get it both into open and closed loop modes on the ecu so it relearns. I've got my finger crossed for your car, man. Shoulda been more patient....
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Old 03-20-2006, 03:09 PM   #262
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You mean to tell me you just added E85 without having larger injectors? With me running 100% E85 with 800cc injectors the Injector Duty Cycle reached 92%. I would guess you went into limp mode from being extremely lean. When I first tried E85 I put in about 75% E85 and car would barely run until I adjusted the fuel flow.
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Old 03-20-2006, 03:13 PM   #263
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I put about 60-70 miles on it before I really kicked it around, driving out to one of my friend's houses. I drove it with varying intensity until I could feel the ECU had compensated for the fuel switch. (it was REAL apparent the change from a fresh start on the E-85 which made the car feel like it was gagging to the nice smooth power which feels much "flatter" than the curve on gas) I am confident nothing is damaged, the car goes into safe mode to prevent such damage.

I was just wondering if anyone had experienced this before with an STi and was able to narrow the problem down to simply running too lean, or a sensor error on the intake tumbler, O2, EGT, or whatever. I haven't had a chance to get the exact CEL code off the ECU yet.
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Old 03-20-2006, 04:48 PM   #264
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yeh, it was definitely running lean once you got into high boost levels and your injectors couldnt flow enough. put regular gas in your car, reset your ECU and upgrade the injectors.

fatray, whats your setup up turbo wise? how much boost were you running? 92% on 800s is alot, just wanted to see whats causing it.
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Old 03-21-2006, 01:01 AM   #265
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It was around 19psi at 7,500rpms and 10.4 afr, on an 18g.
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Old 03-22-2006, 05:24 PM   #266
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ok, so I am just getting into this and am intrigued by the use of e85, plus living in MN it is a very good option for me

sorry i haven't read through this whole thing, but i have read some of the beginning, and had some specific questions that i dont think were addressed in full. Hopefully this will also help inform others wondering.

This is for Hotrod,

I am trying to understand how it is possible to run 100% e85 on a stock ecu wrx, let alone any car with stock engine management.

So, if i am thinking about this correctly, ECU's actually read in lambda, so a 1.00 reading of stoich is 14.7:1 in unleaded but 9.765:1 for e85, and all the ecu cares about is that it hits 1.00 when it is supposed to, correct?

If this is the case, 1.00 indicates complete combustion. If there is incomplete combustion, what is the 02 sensor measuring? I am assuming it is measuring waste by products.

but here is where i get confused(if the above assumptions are correct), is it measuring for common waste byproducts common to both of those fuels?

for example, lets say the 02 sensor senses a 20% excess of "fuel" in the exhaust, which would be .80 lambda 11.76:1 for reg gas and 7.8:1 for e85. but, those two fuels are molecularly different, so how can the 02 sensor be sensing "fuel" obviously its not, but are there certain molecules common to those two fuels it uses, which then makes it possible to use e85 and reg gas interchangeably without issue?

and also, would you agree to actually take advantage of the benefit of e85, tuning is needed correct?

also, what is actually then being done to these cars that can run on e85, if you can technically just put e85 in any car really, do they just have a bit different ecu mapping to take advantage of the diff power vs AFR?

thanks for the help, this is very exciting, i love learning.

Ben
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Old 03-22-2006, 07:08 PM   #267
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Quote:
all the ecu cares about is that it hits 1.00 when it is supposed to, correct?
Correct that is the target for closed loop fueling, If it can hit that without pushing its fuel trims too far out of the normal range it is a happy camper.

Quote:
If there is incomplete combustion, what is the 02 sensor measuring? I am assuming it is measuring waste by products.
Not trying to be snide --- its an O2 sensor, it measures free oxygen/ or oxygen demand in the exhaust gases. If there is excess Oxygen then it is lean, if the exhaust gases have excess fuel, (ie want more oxygen to react with) it knows its rich.

There are a couple really good web sites out there that discribe the chemistry and process the O2 sensor uses. It is really dirt simple technology in many ways.

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would you agree to actually take advantage of the benefit of e85, tuning is needed correct?
Not entirely true. A stock ECU running on about 30% E85 mix will automatically make use of the extra octane available so you will get smoother idle, and better performance due to better ignition timing. At higher mixes, the answer becomes more and more yes. The car will run fine on a 50% mix but not at its potential because your pushing the stock ECU outside its design limits and it gets grumpy and throws a CEL.

At 100% E85 you will notice definite drivability problems if you have not increased fuel flow.

Car starts a bit hard in cold weather, and you can feel the switch over from closed loop to open loop fueling. You will also be running quite lean so could cause problems if you really flogged the car hard.

If you have no plans to modify the car, I would stick with a 30% mix and be done with it. If you want to throw a set of bigger injectors or increase fuel pressure or both to get to 27-30% more fuel flow than the ECU thinks it is giving you, then you can run 100% E85 with good performance and very minor drivability problems on 100% gasoline. (at least based on my experiments to date)

You get a just detectable surge as the ECU switches from closed loop to open loop because the fuel air mixture takes a huge jump when you are on pure gasoline. On 100% E85 it drives better than stock on gasoline in my experience.


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what is actually then being done to these cars that can run on e85
Most of the changes are tweaks to the ECU control range for fuel mixture, many are using a sensor that figures out the fuel blend (although there appears to be a move to just give the ECU a lot more control range and let it find the proper settings at closed loop fueling and then apply that adjustment to the open loop map) Many of them run slightly higher compression ratios to make better use of ethanols high octane and improve fuel milage on E85.

They change a few things in the fuel system, different fuel pump in some cases, different fuel tank and filler design in some for example. They have to make changes to the emissions system so it properly handles evaporated emissions. Mostly technical EPA stuff.

Being Lawyer driven large manufactures many of the changes in my opinion are not really "necessary" but are nice to have changes. For example they put a flash arrester in the fuel filler neck because ethanol has a wider flammabiliy limit at common temperatures, and could theoretically flash back into the tank. By the same token gasoline is much more flamable in cold weather. We don't worry much about the ignition risk of gasoline vapors in cold weather but they (due to a lack of experience) assume it is important to worry about the same sort of issue with ethanol at normal temperatures.

Larry
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Old 03-22-2006, 07:08 PM   #268
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editted for being too late.
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Old 03-22-2006, 08:03 PM   #269
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yes, I am aware its an 02 sensor, but it is measuring waste byproducts for that oxygen content, if there is CO, it is rich, if there is extra O2, then lean.

I will be running a hydra, so my car will be modified, a 3.0 H6 turbo in a 2001 legacy is fairly modified, well IMO

ok, so i understand the closed loop operation I guess, how is the open loop map determined, by actual previous closed loop testing by subaru to show how much injector opening time is needed at that load to hit a certain lambda? But you are saying there are adjustments made to the open loop table as well, which makes sense but then why do you need to make adjustments to the fuel system to run 30% more fuel.

if open loop table in the stock ecu table shows that it should be hitting lets say 11.0:1 that should equal 7.3:1 for e85 if we are looking at lambda correct? That is close to pretty much the rich limit for max torque for e85, so wouldnt you possibly want to even lean it out vs run more fuel? or does that only work when in closed loop operation, and the previously determined injector opening for 11:1 reg gas will not get you a 7.3:1 for e85?

Ben
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Old 03-22-2006, 08:08 PM   #270
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Larry (Hotrod),

Okay, I've posted in this thread but have been inconsistent with the information posted. I know at one point or two it was discussed on the AFR that is read on a WB gauge and how it may differ. So, let's say that I've got a LM-1 WB. Do I leave it to read gasoline values or switch it to ethanol? Hell, I don't even know for sure if you can switch the actual LM-1 hardware unit, but I do think you can log with it to read ethanol.

Sorry, I'm still a little confused on the use of an AFR device and reading the ethanol.

Thanks,

Todd
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Old 03-22-2006, 08:19 PM   #271
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ok, nevermind on the needing 30% more fuel, i was not thinking, haha, i get it now. even though both are stoich at 1.0, they are diff ratios, which requires more fuel, DUH:-P

Ben
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Old 03-22-2006, 08:22 PM   #272
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Quote:
Originally Posted by tmarcel
Larry (Hotrod),

Okay, I've posted in this thread but have been inconsistent with the information posted. I know at one point or two it was discussed on the AFR that is read on a WB gauge and how it may differ. So, let's say that I've got a LM-1 WB. Do I leave it to read gasoline values or switch it to ethanol? Hell, I don't even know for sure if you can switch the actual LM-1 hardware unit, but I do think you can log with it to read ethanol.

Sorry, I'm still a little confused on the use of an AFR device and reading the ethanol.

Thanks,

Todd
are you trying to compare stock vs. stock? It would make most sense to me to log stock AFR on regular gas, then log that same afr on e85, and see if it is the same. But maybe that isnt what you are asking

basically you will only be caring about the delta of the two and can figure out the AFR differences from some math.

if i am thinking correctly, which sometimes doesnt happen.

Ben
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Old 03-23-2006, 08:21 AM   #273
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Quote:
Originally Posted by PHATsuby
are you trying to compare stock vs. stock? It would make most sense to me to log stock AFR on regular gas, then log that same afr on e85, and see if it is the same. But maybe that isnt what you are asking

basically you will only be caring about the delta of the two and can figure out the AFR differences from some math.

if i am thinking correctly, which sometimes doesnt happen.

Ben

What I meant was that if I ordinarily would tune gasoline for stoich down to (arbitrary number) 10.8:1 then what would I use for E-85? Now maybe this a question for Innovate (maker of the LM-1) but is there a way to set it to read a AFR range for ethanol rather than having to do funky conversions?

I remember reading that ethanol has a stoich AFR of 9:1 IIRC. So knowing that, it would be nice to tune from an ethanol stoich to what ever the lower end would be (maybe 6:1). Just like you would with gasoline stoich but have the WB unit actually displaying the range for ethanol.

Does that make since?

Todd
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Old 03-23-2006, 12:38 PM   #274
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you just need to have it show lambda instead of AFR if possible, because it is doubtful it has e85 AFR outputs to show, unless you can set what stoich is.

So, if you can have it output lambda and you know 1.0 is stoich, then tune from there. But its not really funky conversions, its simple math

if left set to gas, 14.7:1 will tell you that it is lambda 1.0 if it is richer, it is lower, leaner it is higher, so you can use your reg gas config to give you an idea, because if you are stoich with gas, you are stoich with e85, if you are rich on gas, you are rich on e85 by the same amount, etc...

the issue i am wondering about, is how low can the wideband go to, cause most i have read about can actually only go down to 9:1(i am assuming that is on reg gas, so in actuality you would be fine for e85 tuning i guess). If it can read down to .70 lambda you will be good.

hopefully some of that made sense...

Ben
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Old 03-23-2006, 01:12 PM   #275
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The LM-1 will let you override the default stoichiometric setting of AFR=14.7 but the question is what to substitute when, for instance, you have a half and half mixture of E85 and gasoline. Suppose you're running 100% E85 - would seeing that your true AFR is 8.7 at WOT trigger alarms in your head (as it should)?
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