Here is the full thread in the link below....37 some odd pages that I have tried to take the meat from, but this sounds like something that is worth exploring further. Currently it is quite a bit cheaper than premium, but it does reduce gas mileage. I am going to do some further reading and see about making this a reality on my car. If any of the local tuners wants to lend a hand and use my car as an experiment for future customers, that would be excellent, if not I can do the tuning myself as I do now. But in the mean time I wanted to share my findings...I took the meat of the thread from the original poster, Hotrod on NASIOC. http://forums.nasioc.com/forums/showthread.php?t=803341 How to make your car (Subaru) a FFV at home with very little money or effort. Well I have been sitting on my hands, and biting my lip now for a couple months waiting until I had the data to backup what I am about to suggest. I believe I have figured out how (at least on the Subaru WRX) to quickly and easily achieve a home made FFV. The solution is so simple it makes my head hurt, but I wanted to check it out to see if the ECU would do what I expected it to do. (sometimes those electrons do odd things you don't anticipate) ===================== First a review of the basics. Pure E85 requires about 30% more fuel flow than pure gasoline to run normally. The Stock ECU handles up to a 30% blend of E85 with absolutely no problems, not even a CEL. The Stock ECU will run just fine on a 50% blend of E85 but will throw a CEL because it has used up its fuel trim authority of +/- 25% to get closed loop fueling back to Stoich (Lambda 1.00). E85 is a cool burning high octane fuel that will tolerate leaner mixtures than gasoline under high load. Gasoline likes rich mixtures under high load to prevent detonation if its octane is a bit low. ===================== On my first attempt to convert the car, I switched to the JDM STi 550 cc/min injectors and made no other tuning changes. This increased the fuel flow by 25% (stock injectors are 440 cc/min). The car ran beautifully on 100% E85, ran good on 50/50 E85 and gasoline but developed a small hitch on transition to open loop fueling from closed loop fueling near 30% -40% E85.. The light dawns !! At this point I realized that if you could setup a circumstance where the ECU was sitting on zero fuel trims at a 50/50 mix of gasoline and E85 it had enough fuel trim authority to cover both extremes of 100% gasoline or 100% E85. At this point I planned out my next experiment ---- unfortunately it took me nearly a year to assemble the parts I needed (not because they were necessary for the tests, but because I was scratching for the funds, and had other plans down the road and only wanted to do the upgrade once.) For the last few weeks I have been driving in all sorts of weather (including -19 temps) with 100% E85 and now recently a 50/50 mix of E85 and gasoline. Here's the magic combination! All you need to do on a Subaru WRX (2002 -- I assume others will behave the same), is increase your fuel low by 15% over stock. This will make the ECU have zero LTFT's and STFT's on a 50/50 mix of gasoline and E85. If you plan to run mostly on E85 you can set the neutral point a bit higher, if you expect to need to spend a good fraction of your time on pure gasoline set the neutral point a bit below the 50/50 fuel blend. The ECU will use 15% of its fuel trim authority, going positive as you move toward 100% E85 and going negative as you move toward 100% gasoline. I have spent the last couple weeks driving around on -15% fuel trims and the car runs just fine. The easiest way to add 15% to the fuel flow, is to up the fuel pressure from 43 psi to 57 psi. This has two minor down sides. If you have an upgraded turbo (and fuel pump) you will run out of injector at high load (not good --- don't go there). On the stock turbo you will also run out of fuel pressure and flow from the stock fuel pump at high boost (need to add a high flow fuel pump if you run over stock boost levels). The slightly more expensive way to do it, if your interested in performance, is to install larger fuel injectors, an upgraded fuel pump and either adjust fuel pressure or re-scale the injectors with one of the aftermarket tuning solutions. This is what I did, I have an Aeromotive adjustable fuel pressure regulator, 800 cc/min decapitated injectors and an ECUtek reflash. Harvey at Super Rupair in Boulder has been worth his weight in gold helping me get the reflash tweeked properly to prove to my self I am on the right track. He's made nearly daily adjustments to the map as I tried out different things. Thanks Harvey !!! (and all the guys at Super Rupair who have worked with me on this experiment). More tuning will follow as I work out the final setup I am looking for, but I wanted to get the word out so some of the other E85 experimenters could do some peer review of my concept and prove if it is a safe and reasonable solution for the average user. Larry Last edited by hotrod; 02-11-2007 at 10:10 PM.
Quote: So have you logged +15% fuel trim being applied throughout WOT with 100% E85? And -15% LTFT with 100% gasoline? Not completely, still burning a high ethanol mix at the moment (last week was all at 50/50 mix), trying to get some milage figures. I'm currently getting 24.3 mpg on the 50/50 mix which is better than most folks can manage around town on gasoline. I have run the 100% E85 and with no changes in the tune, on the 50/50 mix its applying a -15% LTFT. I played with the fuel pressure a bit and found everything is consistant with my expectations. The base line tune on E85 has near zero LTFT and it is now -15% on the 50/50 mix. I will get the injectors rescaled this coming week to bring the LTFT down to zero then we can start some more controlled tests. It will take several more weeks to get enough miles on the car to finish a comprehensive battery of tests but I feel confident with the results seen so far, that there will be no surprises. On the 50/50 mix using the E85 baseline tune it is still showing a IAM of 16 across the board with no knock correction at any rpm or load I have been able to hit. The Wideband just got installed yesterday and confirmed the readings I'm seeing in the Delta Dash logs, so I know I can trust the DD log numbers for AFR within a decimal or so. Waiting on the arrival of a new EGT to finish up the instrumentation I need before I start pushing it. I still want to lean it out a bit, both in open loop and on tip in. Harvey is still tweaking the MAF scaling to get it exactly right for my intake setup. Then I will start beating on it a bit as the weather warms up. Kind of tough to flog it really hard when its foggy and snowing and temps jump up and down from -19 lows one day to 55 degree highs a couple days later. Quote: This is great news! What happens when you transition from a 100% Petorul, to 100% E85? How long until the you run from -15% to +15% fuel trim? As above have not done the 100% gasoline runs yet (since they are the most risky due to its lower octane) I will do that last. The LTFT's change very quickly but take a while to stabilize on a fixed value. I bumped the mixture up from 50/50 mix this morning to about a 75% E85/ 25% gasoline mix and the trims went from the -15% on 50/50 mix to -7% trims within 2 city blocks. The Wideband shows the ECU was hitting Lambda 0.99-1.01 before I pulled out of the gas station. More to follow, as I keep nibbling away at this. I want to get all these numbers using typical daily driving so it takes a while to crank off the miles. That is one of the reason I wanted to give a heads up to the other experimenters to get them thinking and testing along the same lines. Larry Last edited by hotrod; 02-11-2007 at 04:38 PM. hotrod is offline Report Post FFV test#2 completed sudden transition from 50/50 mix of gasoline and E85 to a tank of 100% gasoline. I ran the car on a 50/50 mix of E85 and gasoline for a bit more than 2 full tanks (600 miles). I tweaked the injector scaling so that on that 50/50 mix the LTFT's and the STFT's approached zero ( By that I mean the sum of them was zero +/- 5%). I then ran the tank down to about 1/2 -1 gallon into the reserve (fuel fill light on for 10-15 miles) and then filled the tank with 91 octane Premium gasoline. Upon starting STFT's immediately (within 10-15 seconds) had scrolled up to -25% then the LTFT started to decrease. LTFT's and STFT's settled in around the near zero area but were slightly higher than I expected 0 ===> +8% on occasion. The good news is that the switch to gasoline is a graceful failure mode, in that if the ECU does not immediately apply full correction, the mixture goes rich. Watching the Wide Band, cruise mixtures still settled in at Lambda 0.99 - 1.00 but you could see it was bouncing around more before it settled. About 10 miles after I put the new fuel in the tank I did a WOT blast and saw mixtures on the Wide Band of 0.69 ( 10.143 AFR ) --- to ---- 0.72 (10.584 AFR) These are essentially the stock AFR's !!!!! Now I will watch things and see how the fuel trims settle in. There were no drivability issues with the sudden switch of fuels other than an occasional pop from the tail pipe. I'm going to let the car cool a bit and run it through a couple more driving cycles here in a bit. Stay tuned for more of " How the ECU Turns " ( I know more controlled tests would be useful but I am trying to get a first pass "coarse evaluation" before I start confirming the fine details. Next I will run this tank down to the fill light and throw in some straight E85 and see what happens.) Larry It takes time, each driving cycle it is closer. On my second driving cycle (15 - 32 miles) the LTFT's hung around -11.8% ===> -14.1%. I just finished my 3rd driving cycle since the change in fuels. Total of 55 miles. In light throttle cruise it is showing a LTFT that varies from -14.1% ==> -15.7%, so it is closing in on exactly that number. Just out of curiosity Jon --- do you know what the ECU defines as a "driving cycle" ? Does the engine simply need to be shut off, or does it need to cool enough to go through warm up enrichment steps. =============== In the for what its worth department, the way the LTFT's are acting is I think the ECU may keep a moving average of the LTFT somewhere for certain conditions and use that default value the next time the engine is started. The reason I speculate this, is on the first driving cycle most of the adjustment was made in the STFT and the LTFT tried to stay near its historical average prior to the fuel change. After shutting the car off, when it was restarted for the second driving cycle the LTFT immediately jumped to a value that was near the average adjustment it needed on the first driving cycle until it warmed up, then the LTFT started moving around again, and slowly got more negative as I drove. After shutting the engine off and starting the 3rd driving cycle the LTFT did the same thing, it immedialtely went to a -15.7 value and stayed there until the engine warmed up, then both the STFT and LTFT moved around a bit as the LTFT gradually settled near -14.1% most of the time. We will see what it does on the 4th driving cycle, after the engine has some time to cool off. Larry
How to make your Subaru a FFV Update II Okay I finished enough testing to post a recipe for a home built WRX FFV. I have satisfied myself that the following concept is sound as the car is behaving as I expect, and so are the fuel trims. You can run this in two different modes. You can let the fuel trim authority of the ECU do all the work (we will call this "autotuning mode"), or you can make life easier on the ECU by a minor tweak of the fuel pressure to help it get in the ball park quicker -- (we will call this "user assisted tuning mode"). Autotuning works just fine, but takes about 4 driving cycles for the ECU to settle into final LTFT's. It is a bit less than optimal tuning at the ragged edge so if your tune is a max power tune I would not recommend this. For a happy daily driver at moderate boost levels (<17 psi) I think it will be safe unless there is something amiss with the base tune on the ECU. Step 1 -- Upgrade fuel pump to a walbro GSS 342 255 l/h pump or equivalent. Upgrade fuel injectors to have at least 30% more max flow than stock. Install an adjustable fuel pressure regulator and an under hood fuel gauge. For autotune mode. Set the fuel pressure at 45 psi and get the ECU reflashed with an Ecutec or equivalent reflash with a 50/50 mix of E85 and gasoline in the tank. Use the fuel you normally have available and summer blend 85 if available (winter blend E85 is about 70% ethanol so if tuned with the winter blend, richen the mixture a tad in the wide open throttle areas.) On the 50/50 mix of gasoline and E85 at 45psi fuel pressure you should have the flash setup so you get LTFT's that settle down near zero or slighly negative ( 0 to -5% ). If you simply add 100% gasoline to the tank, the ECU will auto tune to -10% to -15% fuel trims. You will get normal stoich AFR's while in closed loop but your WOT AFR's will be a bit rich (around 10:1). If you simply add 100% E85 to the car and let it auto tune, you will get normal stoich AFR's in closed loop fueling and your open loop fueling will be a bit leaner than the tune at 50/50 fuel mix by about 7%. ========== For user assisted auto tune mode, you simply adjust the fuel pressure slightly when you make a major change in the fuel in the tank. 35 psi for 100% gasoline 45 psi for 50/50 gasoline and E85 55 psi for 100% E85. If you adjust the fuel pressure as above, you will keep the ECU near 0 LTFT's and your WOT AFR's will be only slightly effected by the fuel switch. The adjustment of fuel pressure does not need to be precise. Simply make a ball park guess what the blend in the tank is, and you will be close enough unless your running a high boost system that needs the full octane of the E85. In that case, I assume you have access to some sort of logging ability and or a wideband so you can tune accordingly or have a dedicated 100% E85 max performance map. ============= My setup (essential mods for the FFV conversion) Aeromotive adjustable fuel pressure regulator. 800 cc / min decapitated OEM injectors. Walbro GSS 342 255 l/h fuel pump. Ecutec reflash -- tuned at 50/50 mix of gasoline and E85 with -5% LTFT's after is settles in (more than 4 driving cycles). WOT wide band is showing 0.82 - 0.84 lambda on the 50/50 gasoline, E85 fuel mix. (non-essentail mods) upgraded fuel system under the hood (fuel rails and new braided fuel lines) More details to follow as I get more miles on the setup and get better info. 50/50 gasoline - E85 mix giving me 24 mpg, same milage on 100% gasoline. I will update the fuel milage on 100% E85 when I finish this fuel tank, but am guessing it will turn out to be about 22 mpg. Larry Last edited by hotrod; 02-22-2007 at 08:27 PM. The earlier Subaru's seem to handle E85 about the same as the WRX but perhaps a bit longer to adjust. I have both an 86 turbo GL-10 and a 88 GL with the NA engine. Both will run lower blends just fine (down around 30%). If I give them lots of time to adjust (a tank or two) they will run higher blends in hot weather. Cold start behavior gets funky if you put 75% or up blends in them, but just the other day for grins I went from 100% gasoline to about 95% E85 by filling up an empty tank of gasoline with straight E85. The car drove just fine while it was hot but over the next few days it got grumpy when you first started it. Once warmed up fully though it handled the high E85 blend just fine. Yesterday I added 5 gallons of gasoline to the tank and its behavior is pretty much back to normal. Just start at lower blends 3-4 gallons per tank and see what it does. If you have a lot of build up of varnish in the fuel lines from running years of gasoline with no ethanol in it, don't be surprised if it cleans a bunch of that crud out and plugs up the fuel filter. (it may or may not --- some folks have problems with filter clogging and others never have any difficulty at all, it depends very much on your local fuel quality and the individual car.) Larry Just a little update on the E85 conversion project. I've been running on 100% E85 for several fuel tanks and the long term fuel trims at idle have stabilized at a rock solid 14.8% so my attempt to get a good split is only 0.2% off of ideal. In watching the fuel trims over time, I would suggest that folks attempting this watch their idle (engine warm) long term fuel trim. It is very stable and does not move around as much as the LTFT does at other throttle settings. Currently fuel milage on the 100% E85 is running in the low 20 mpg range, compared to a long term average of 24 mpg on straight gasoline before I began this last major conversion process. That gives a milage reduction of about 15% - 18% depending on how I drive. Given the fuel price paid today for E85 vs current fuel prices for 85 octane regular, I am running a 105 octane fuel for the equivalent cost per mile as if I was buying mid grade gasoline. (note I have been running significantly higher boost recently that I ever tried on the older conversion with the stock turbo or the 16G before I had enough injector to feed it, so some of the fuel milage loss is directly related to higher power levels) I think there is more milage there but I have resisted the temptation to keep fiddling with the tune for a while to get stable numbers as a baseline for future comparison. Larry Quote: I am running a stage one map from osecuroms, would I still want to run the 30% ratio(meaning 50/50 e85/93 or e85/87) or can I go to higher percentage ~35-40%. Quote: so considering I have the math skills of a chimp what's my ratio. 2 gallons of E85 out of 9 total I would call a 22% blend of E85 (true ethanol content between 15% and 24%) Most of us do not worry about the actual percentage of ethanol in the mix but for convenience use only the volume ratio of E85 to gasoline. When I say a 30% blend of E85 I am saying 3 gallons of E85 mixed with 7 gallons of gasoline. (which would have an actual ethanol content of anywhere from about 25% to 33% ethanol depending on -- if your local E85 blend is a winter blend of 70% ethanol or a summer blend of 85% if your local gasoline is oxygenated which is usually a blend of 5.7% ethanol but is legally allowed to go as high as 10% ethanol). In short it is way too complicated and uncertain to try to figure out the actual ethanol blend in the fuel for most purposes, and quite frankly does not matter much as the car seems to have a very wide tolerance for small changes in the ethanol content. To answer your question --- Yes I always recommend that folks start out with a 30% blend or less and then work up to see how their car reacts to the mixture. There are so many variations in tunes, driving style, driving conditions and local fuel blends that it makes much more sense to work up on the blend. It also gives you the information to know how much E85 you need to add before you see any useful changes in performance and knock resistance. Local pricing varies widely as well so the most economical mix for one driver may not be for another. After you know how the car reacts to various blends of E85 and premium then you can experiment with blends with lower grade gasoline, but I would suggest you stay with mixes of E85 and pump premium at first. Just being conservative here --- I would hate to have someone break something simply because something about their setup did not let them run the higher blends or they jumped directly to low % blends of E85 and cheap regular gasoline and did not have the octane they needed for their setup. Larry
A cautionary note for anyone playing with E85 seeking to copy my home made FFV project. After some testing today, I think I would have to issue a strong caution to using the "autotune mode" if you are running any significant boost levels (over 8-12 psi). As you know, I recently have been running a bit lean, and part of that was due to the recent change over from winter to summer blend E85. Well I managed to scare myself today! I have recently been exploring fuel economy issues with the E85, using the midrange fuel pressure setting and let the system use LTFT's only to handle the E85, starting from a safe tune at a 50/50 gasoline-E85 blend. The result is, I made a few too many tweaks to lean the mixture out, working entirely in the low boost range. I first did a bit of logging and found that driving like a normal human being in daily traffic, I rarely went over 2-3 psi boost in typical city traffic. On the few occasions that I did, I seldom was on boost long enough to get over about 8 psi boost (this was in economy driving mode, ie easy into the throttle avoiding WOT squirts). I have been driving on the summer blend E85 now for a couple weeks so all the fuel trims had fully stabilized and today was a nice cool day with some light sprinkles of rain, so I thought it was a good time to do a couple of WOT runs and see what was happening under those conditions. I found that I was running lambda 1.02 ( 15:1 gasoline AFR) all the way up to 18 psi. Eeeeeekk! Needless to say it did not take me long to get out and crank up the fuel pressure to 55 psi. That dropped my Lambda under WOT open loop down to 0.82. The good news is, I was expecting it to be a bit too lean, so had been purposely avoiding flogging on the car hard. I was also so lean I was over on the lean side of the high detonation mixtures. No harm no foul, but just a red flag and a word to the wise, it is easy to get so carried away "tweaking the system" that you go a bit too far! All that said, I think it still has some possibilities for folks that are willing to run low boost or NA setups strictly for the true FFV capabilities but I would not recommend it now, especially on the summer blend E85 if you like to run the car hard. Autotune would work fine if you also had a water injection setup however. The other observation is that the single best thing you can do to increase your fuel milage is to change your boost curve! I have a Blitz DSBC which has 4 settings (channels) and I can set the boost gain independently on these channels. By running a very low gain on the first channel I can create a situation where in day to day driving my boost seldom gets up above 3-6 psi and a full WOT pull will only go up to about 1/2 of the max boost limit I have set. Then by simply twisting the knob to channel 2 which has a higher gain on it I have a normal agressive boost profile. Using the low gain setup I bumped my fuel milage from 18 mpg to almost 24 mpg with no other changes. In short agressive quick spooling boost curves are your enemy if your looking for good fuel milage. Larry In closed loop operation, the car is constantly trying to target a lambda of 1, regardless of fuel. Changing your fuel (and thus changing the volume needed to achieve stoich) will require changing the rough correction for injector opening time -- the injector scalar. Up to a certain limit, the ecu will be able to compensate for this via the long term fuel trim but after a certain point, a CEL will be thrown. The correct way to deal with this is to set a proper injector scalar that allows to the car to hit stoich in closed loop while minimizing the amount of LTFT learning. In open loop fueling operation, the car runs off of the fueling tables that we see in either Enginuity or StreetTuner. However, the ecu actually uses these as enrichment tables over stoich; lambda tables essentially. Both Enginuity and StreetTuner convert these tables (although I believe that ST can possibly show it as lambda values) to show values that equate to gasoline AFRs. The ecu will do the necessary calculations based on your injector scalar to determine the correct ontime for the injectors to achieve the desired richening over stoich. So, for your open loop fueling to be correct, you first must have the correct injector scalar size to achieve stoich in closed loop. Doing this with regular gasoline is easy -- the car comes from the factory with the correct injector scalar already set for you. Change your fuel and you will need to change your injector scalar. However since the best torque rich/lean values for e85 differ from gasoline, your fueling table will also need to be adjusted to account for this after you have found the proper injector scalar. Simply changing your fuel targets in the closed loop fueling tables and doing nothing else is INCORRECT. I had to "richen" (ie, make the injectors open longer to allow for a greater volume to flow) my injector scalar ~ 29% when going from regular gasoline to pure e85. Cold starting issues are due to the basic physics of ethanol. It does not produce a flammable mixture with air below about 55 Deg F. At low temps you are depending entirely on the gasoline component in the fuel to get the initial ignition to start the engine. Once the engine gets some heat in it the problem goes away. So you need to do things that improve the flammability of the fuel air mixture during cold start. One procedural trick is to turn the ignition on and let the fuel pump build full fuel pressure before you crank the engine over. That ensures that the fuel injectors produce a high quality fuel mist when they first spray fuel into the intake. I also in very cold weather hold the key in the crank position just a fraction of a second longer as the engine fires so the first crank or two is starter assisted. That helps a lot in very cold weather. Good ignition helps light off a lean fuel air mixture so wider spark plug gaps, good quality spark plugs (probably want to change them out a bit sooner than you would on gasoline) and a nice strong battery that will crank the engine fast and still provide good voltage to the plugs makes a difference. Adding a little extra ignition advance at cold cranking rpms will give the mixture more time to get burning before the piston runs off and leaves it behind, since lean mixtures burn slowly in a cold engine. One step warmer plugs in the winter is another work around. Anything that adds heat to the intake air will also help. In bitter cold weather putting a drop light under the hood at night will hold air temps under the hood up in the 30's - 40's even in subzero weather. Pulstar plugs work, they improve cold starting and allow the engine to pull better at very low engine rpms. My car will pull a load about 200 rpm lower with them than I can on conventional plugs, but they are not magic and will not fix all starting problems. They do illustrate how important a hot spark is to cold starting though. I like them but for folks that have high power setups they may not have the heat range choices folks want. I think new conventional plugs would work just about as well. Years ago it was very common for folks to install new plugs in the fall to ensure good starting when the weather got cold. The most practical solution in very cold weather may simply be to throw in an extra 2 gallons of gasoline just before a cold snap. Larry hotrod is offline Report Post Reply With Quote
hotrod you have you come up with a more concrete formula for calculating injector sizing It depends a bit on how conservative you want to be but you can get a pretty quick estimate doing it this way. Fuel flow required is directly proportional to the total air flow, which obviously changes with boost pressure etc. On gasoline, you need about 1.6 - 1.8 cc/min static flow on each injector for each hp the engine makes (4 injectors total) You need about 2.0 - 2.3 cc/min static flow on each injector for each hp the engine makes on E85 (4 injectors total) 1 HP approx equals 1.45 CFM = approx 0.108025 lbs air flow Our engine needs about 0.59 lbs of gasoline per hp / hr. Each gallon equals 3785 cc, and gasoline weighs about 6.2 lbs/ gallon, so that 0.59 lbs of gasoline is 0.095 gallons or 360 cc/min injector flow on 4 injectors. That means you need 90 cc/ hr injector flow per hp or about 1.5 cc/min per injector to make one hp on gasoline. Since E85 requires about 30% more fuel that works out to about 1.95 cc/min of E85 to make a hp. Since you can approximate the maximum power you can make based on the airflow in CFM divided by 1.45 that is a handy way to ball park your injector size. For E85 take your turbochargers max flow in CFM at the boost you expect to run and divide by 1.45, then multiply by 2.0 and you will be pretty close in cc/min for each injector. For gasoline it would be divided by 1.5 giving 403 cc/min on the stock turbo with gasoline. Stock turbo flows 390 cfm max flow at 14.7 psi 390/1.45 x 2.0 = 538 cc/min on E85 16G small max flow 505 cfm 505/1.45 x 2.0 = 696 cc/min on E85 20G max flow 695 cfm 695/1.45 x 2.0 = 959 cc/min If you do not want to muck around with the formula it simplifies to turbo air flow in CFM at the boost pressure you intend to run x 1.38 will give you the approximate cc/min static flow you want to use for your injectors on a 4 cylinder engine. simplified formula : assuming 4 cylinder turbo engine (CFM at target boost) x 1.38 ~= static injector flow cc/min for each injector Quote: well i did it this time! i did a 50/50 mixture (50% E85 & 50% 85octane), the only Check Engine Light i got is the p0171 (system to lean, bank 1) at 1/2 tank and again at 1/4tank, this only happens when i run over 30% E85 mixs. so is the ecu telling me that the injectors are maxing out and it's cuasing the "system to lean" code? Yes the ECU is using up all its tuning authority to get to normal mixtures in closed loop and you will be running a bit lean at WOT. On the stock turbo you are power limited (and air flow limited) so that although it is not ideal you can run leaner than ideal at WOT if you don't stand on it for extended periods of time. Quote: If he's not running a stock map than I would suggest not putting any E-85 in his car. The CEL isn't just some kind of annoying thing. It's your engine running too lean in most situations. Tuners sell different maps for 91 and 93 octane. If you put a wildly different fuel in there your asking for disaster. Actually based on my experience the CEL is mostly a nuisance I have several thousand miles on a stock turbo WRX running 30%-50% blends of E85 with no problems. The high octane of E85 (road octane of about 112) and its high cooling capacity and cool burning characteristics make it much more forgiving to lean mixtures than crap 91 octane pump premium. It is not "ideal" but it is also not asking for disaster, but rather suggesting caution to avoid extended periods of high load. Since no two engines and drivers are identical it certainly demands that the driver make informed decisions regarding how far he is willing to push the envelope, but this fuel will tolerate upwards of 35 psi of boost without detonation at proper rich mixtures so there is lots of cushion there to work with. If you look at my discussion of my experiments with a home grown FFV on E85 I ran stoich mixtures at 10 psi boost with no detonation or other problems. Not recommended to do intentionally ( which is why I caution against it) but there are plenty of folks shouting the sky is falling regarding E85 so it is important to point out it is different than gasoline and things that would kill your engine in a heartbeat on gasoline are not necessarily bad on E85 mixtures. Quote: If he's not running a stock map than I would suggest not putting any E-85 in his car. We have probably 100,000 miles of experience with E85 in several different cars with much more aggressive setups than he is running. I personally have about 45,000 miles of E85 usage on my WRX much of it while running exactly the blends he is talking about and very similar setup. A 30% blend in my view based on that experience is absolutely safe for his setup. 50% blend would be an educated risk which only he can evaluate by looking at his spark plugs, and any other info he might have from logging, engine temps, EGT's and knock correction etc. Larry
Quote: Have you tried opening up the A/F learning limits to try and make the ECU act like a true FFV? Check the front page of the FAQ I have a note in there on the post number where I discussed a home made FFV. It is easy to do and you do not need to alter the tuning limits. All you have to do is scale the injectors so you have near zero fuel trims on a 50/50 mix of E85 (ie about 15% larger than stock). The stock ECU has +/- 25% fuel trim authority which is almost enough to get a full FFV setup, but you need to scale the injectors so they sit in the middle of that range at a 50/50 blend to be able to use it all. For a daily driver with a small turbo that works fine but the car will run a bit lean at WOT. I did it for some time but if you are running a big turbo and serious boost I would caution you to make an effort to richen up the open loop map. You can add some low tech tuning ability by adding an after market adjustable fuel pressure regulator and running about 55 psi fuel pressure on 100% E85 to richen up the fuel map even without any reflash ability. 550 sti pinks are just about perfect on the stock turbo, and will allow you to run any where from 30% -100% E85 on the stock ECU. With a reflash ability you could easily cover the whole range. You will run out of injector on 550's if you run a bigger turbo and high boost, unless you jack the base fuel pressure up into the 50 psi range. Quote: yes I have seen the formula to produce the injector size of need, but I don't know what my cfm is. What turbo are you running and what is the maximum boost you plan to run? Look at the turbo FAQ and you can figure out your maximum air flow. By the way folks a brief update. I recently have had some cold start problems with my setup, and it appears this is due to the switchover of the local E85 to the summer blend (85% alcohol) from the winter blend (probably 70% -75% alcohol). The switch appears to have happened the last week or so of March or the first week of April. I need to richen up my tune slightly in the low rpm ranges near idle. The winter time base tune is a tad too lean for good cold starting on the summer blend at temps near 45 deg and high humidity. Quick fix is the same as for winter cold starting just chuck in a couple gallons of gasoline with the 100% E85 and problem magically goes away. The symptoms of too lean on start, is the car will not fire immediately on the first few cranks and when it does fire it stumbles and coughs for a second or so before the idle cleans up. heavy throttle application when cold will lead to lean back fire in the intake manifold. Problem goes away as soon a engine gets up above about 100 deg F water temp. I have been trying to figure out how the system behaves in that first 3 -4 seconds after you start the engine. I suspect that the problem is that when you shut the engine off the idle air control valve goes to its home position (not sure if that is wide open or fully closed). Then right after the engine starts the IACV attempts to get control of the idle speed, and the mixture is determined entirely by the default mixture and post start enrichment since the front O2 sensor is not active yet. It is during that phase of the startup and post start run that it struggles. Having grown up during the era when some cars still had manual chokes, and struggled for months to get my automatic choke on my Hemi to work right, I immediately recognized what was going on as all the symptoms matched with a car that did not have the choke set right. It just took a while for the brain to realize the E85 blend may have changed on my last fill up. The weather in that time period was quite variable so I would have shirt sleeve weather for a couple days then a cold damp morning followed by a couple more nice warm days so it took a couple weeks to get a good feel for it. (I'm not sure the lean mixture back fires were bad enough to damage the intake if it had been plastic but I know what you mean, I have had cars pop back like that and bend choke plates and jamb them in the air horn of a carburator. I also know of folks that have blown the guts out of air filters due to lean backfire). On a totally unrelated topic, I'm a happy camper, I just ran the WRX through emissions and passed with flying colors. 100% summer blend E85 with an extra 1.5 gallons of gasoline added to the summer blend, on Harvey's baseline tune, I have a single Spintech high flow cat in the exhaust now. For those of you that don't know the Colorado emissions test is a driving cycle,(I/M 240 test) on an AWD dyno test so these are under driving condition tail pipe emissions on E85 . http://www.aircarecolorado.com/im240tst.htm Engine has 59K miles on it, with over 100 drag strip passes on it, no detectable oil consumption, converter is new. Code: ............ reading .... limit ... HC GPM 0.3335 1.20000 CO GPM 3.9638 20.00000 CO2 GPM 414.3504 -- NA --- NOx GPM 1.9216 3.00000 The National Center for Vehicle Emissions Control and Safety at Colorado State University has done extensive testing of in-use vehicles and their converters. Part of the testing included the development of converter feedgas charts for fuel-injected and carbureted vehicles (see CO, HC and NOx feedgas charts below). gpm = grams of pollutant per mile driven Fuel injected 4 cyl HC ~= 1.0 - 2.0 gpm CO ~= 10 - 15 gpm NOx ~= 1.3 - 2.0 gpm Based on those numbers my NOx is a tad high so I will richen up my tune a bit as HC & CO is well under control. Also a richer mixture is better for a max performance tune on E85. Once I get my water injection setup re-installed that will also drop NOx a considerable amount. Larry Quote: Just the stock turbo and max boost of 18 psi No problem 550 pinks would work good for that. That is essentially what I had when I was running the 550 STi pinks on 100% E85. I could go down to about 30% E85 before the car started to show it was running rich due to too much gasoline in the fuel blend. It would still work fine but you could tell it was very rich and fuel mileage suffered on straight gasoline. An upgrade to a walbro 255 l/hr would be a good idea but not absolutely critical if you are short of funds, and need to wait a while to do that. As above the decapitated stock injectors work well (what I am running right now with a 16G) but you will need to get a reflash or take some other measure to control your fuel mixture. Quote: I don't see any reason to blend fuels. Run a map for E-85 and one for Gas you'll be fine. The blending option is good for folks that just want to put their toe in the water before making a the full plunge, and it is also useful as a diagnostic to see how the car acts if you cannot find E85 when you need it. Keeping a specific fuel blend is really not very critical unless you are running a high power high boost setup. For a daily driver E85 is amazingly forgiving with regard to fuel air mixtures. It will run fine on very lean mixtures or very rich mixtures if you are forced to due to its wide flammability limits. Its high octane protects you against detonation on mixtures that would kill the engine if you were running normal pump gasoline. Obviously the dedicated fuel map is the best way to go if you can but the user should know what happens if he has to top up with gasoline during travel etc. Here in the Denver Area we are now getting to the point that you are never more than about 20 miles from an E85 station. But sometimes due to schedule conflicts it is nice to just toss in 5 gallons of gasoline and know that the car will run just fine. I now have an E85 station near my route to work so it is easy to keep the tank full of E85. If traveling the simple solution if you will have to span an area that does not have easy access to E85 is to just top off the tank with gasoline when it gets down to about 3/4 full. That will keep your ethanol concentration high enough that it will still run normally even on a full bore 100% E85 conversion. I get 270 - 290 miles per tank on E85 if I am making no special effort to drive for economy. If I top off at 3/4 tank with gasoline I will get a total travel distance of about 400 miles out of the car before I need to fill again. That will get you to another E85 outlet almost anywhere in the country now that there are about 1500 stations selling the fuel. Larry hotrod is offline Report Post If you are showing a gasoline calibrated AFR of 11.2 on straight E85 at WOT you are doing just fine on your mixture! Does your wideband show the lambda reading as well as the AFR? If so, shoot for lambda 1 -1.02 at light throttle cruise, and lambda 0.72 -0.76 at WOT for a starting point. You can go a little bit leaner at WOT in most cases, if you are running a small turbo and mild boost (less that 18 psi). But based on my experience you will make more power in the Lambda 0.72 - 0.76 range. My original conversion displayed a gasoline calibrated AFR of 11.5 (lambda 0.78) and the car ran just great but that was on the stock turbo and moderate boost. To convert lambda to a gasoline AFR .... Lambda = displayed AFR/ (gasoline stoich AFR 14.7) To convert lambda to true E85 AFR ....... lambda = true AFR/ (E85 stoich AFR 9.8) Your displayed gasoline AFR value of 11.2 equals a lambda of (11.2/14.7 = 0.76) Your true AFR would be about 0.76 x 9.8 = 7.5:1 Larry
These ARE the cliff notes, lol. Basically it comes down to 30% more fueling and a good tune. It also shows the amazing ability of our ECU. If you were to be on the totally safe side you would run new fuel lines, new filter and different injector o-rings, but several people have been running this set up on a stock wrx (upgraded injectors, fuel pump and regulator but stock lines, etc)fuel system for quite some time now with no problems related to the different fuel. *** for those that don't want to read the whole thing....you CAN NOT just go pump E85 into your car and expect it not to grenade the engine.
haha, funny whenever I post something kinda technical there are very few responses....but the simple stuff like hey does this new HIDZ light kit look good...well lots of responses, lol. Noticed the same with some other threads on here.
I am very interested in E85 as an alt fuel... but isn't the larger question: "how in the hell do you reliably find E85 fuel in GA?"
Yeah, I don't like E85. There is like 1 or 2 stations in GA that carry it (a temporary problem I know), but then there is the UN trying to get the US to make less E85 (at least out of corn b/c of rising gas prices) so who knows what long term availability is? Also how long can you really run this stuff on your stock fuel system? Personally my fuel system is not one I want to have degrade. This is interesting, but for me my next car is a diesel.
it's not that we don't like technical threads, it's just that nobody gives a shit about E85. you can't buy it here, and turning food into fuel is moronic.
Actually there are stations all over. I think there are like 20 some odd stations around metro Atlanta with more on the way. I found there are 2 within 15 miles of my house. One is right off of 985 and 20 on my way home. As for the food to fuel thing, you can actually make it out of pine trees, old tires, all kinds of things, not just corn. For turbo cars it is wonderful as the alcohol burns cooler, allows for more advance, is 100 octain and has a higher expansion rate than gasoline (think more vapors when the combustion is over...thus MORE gas, faster spool, etc.). So for turbo cars this is a big bonus! But if people don't want to take the time to explore alternatives or possible improvements...well what can I say, guess I thought more people would be interested. Back to the endless, "hey does this look cool on my car?" threads.
Some information people might find interesting...lots of people are ignorant about E85. Lots of people think it is just from food. From an E85 site: In addition to grain, ethanol is also produced today from wood waste, cheese whey, waste sucrose, potato waste, brewery waste, and food and beverage wastes. The next generation of ethanol production facilities will include production from cellulose and biomass feedstocks. Earlier this year, there was a groundbreaking for a new ethanol production plant in Jennings, Louisiana which, when completed, will produce ethanol from rice hulls and bagasse. Three other plants are currently planned in California that will produce ethanol from rice straw. One company has plans for production facilities in New York and Alabama to produce ethanol from the biomass portion of municipal solid waste. The plants would reduce capacity problems at wastewater treatment plants and reduce the need for landfills. Many ethanol producers capture carbon dioxide emissions for processing and use in beverages.
with the current food shortage, i honestly think e85 corn or coconuts or whatever can be put to better use. countries like Brazil are fighting to keep the right to use a fuck load of the crop for ethanol. i don't find that right.
I think that there is a lot of good things about E85. I think that the current energy crisis can only be solved by a comprehensive energy plan... one that re-uses waste and turns it into energy such as SOME of the means of making E85. The problem is that I am still not convinced that E85 is anything more than a fad that will go the way of the mini-disc player. I really do appreciate the technical information, but I am a little too conservative to jump on the band wagon on this one.
Yes i read the post, but a majority of it is still corn, and coconuts produced in countries starving for cash. what do you think they will do? sell oil substitutive or raise food for the world? yeah easy choice. Imho id rather have the food.
Hell, there are some guys figuring out they can turn Kudzu into fuel now too. Talk about something we got plenty of. That crap grows a foot a day.
Yes Thank you very intresting read...still on the fence about how I feel about E85...I'm thinking bio diesel though...
I talked to siegel about doing an e85 tune and he said in order to make power from you it you have to use a lot of it. He said cars that they work on are running two walbro's with 1000cc injectors. Completely scratched my plans of using e85
I agree that sounds like way more fuel and a larger bill in the end. I don't see myself even thinking about it anytime soon. What was cool about the write up imo is it gives you an idea of how the car will react if they start adding more than 10% ethanol into the gas mix and moving towards 100%. From what I read it appears the stock ECU will make adjustments as needed when ethanol is introduced to a certian point............ ?question: I wonder how much of a difference there is between 100% gas and a 10% ethanol mix when looking at needing an aftermarket fuel pump and larger injectors. What are the HP limits of the stock injectors and pump with no ehtanol, 10% mix, 20% mix, etc.
Very interesting read, I went over and read the thread on Nasioc. Theres lots of good things about ethanol and power is one of them, its cheap race gas. We have tuned a couple of E85 cars at the shop lately and we are about to tune my 240 on it, Ill post more info when I have time. Matt
From what I can tell, 2 things stand out...the fact that it is 100-105 octane and the fact that it has a higher volume of gas produced as a by product to combustion. Those 2 things sound very turbo friendly! There is a need for more fuel. It is honestly about 22-30% more fuel used than for gas as it has a lower stoich than gas. For an everyday car with stage 2, you could probably go with a single wal 255 fuel pump and some injectors and be ok...safe would be also adding a fuel pressure regulator and jacking up the pressure to 50 psi. But the cool part is it seems that a car producing around 240 awhp will go to around 300 awhp on E85 due to the knock resistance of the 105 octane and the higher gas volume of the burnt fuel.
Using FOOD to power cars is very UN-intelligent in the current market. Making E85 available like gasoline/diesel would use to way too much of the market share of the worlds corn supply. Its already creating shortages. Not to mention it takes more energy to make it than it produces when combusted. Very inefficient.
Not arguing the fact that e85 is a decent fuel just that the vegetation could be used for better purposes in the current world market
What about using garbage, food processing waste byproducts, pine trees (georgia has a lot of those) and all the other methods...think outside the silly corn thing. That was just our government's screw up, giving corn an incentive. There are way better ways and more efficient ways of making ethanol.
Haha, but the overwhelming majority of lumber companies will now plant trees to replace the ones they cut. It's what we like to call a RENEWABLE resource boys and girls!! If we are ever going to gain energy independence, this and bio-diesel are about our two best bets. If we can also reduce land fill masses, even better!! And before anyone asks, no, I don't have any stock in ethanol, just very interested in it and other alternative fuels. I work for a beer company! We have a different type of alcohol!!
Yeah the tree may be renewable but how long does it take for said tree to get HUGE like the one before it? 10+ years. Also what about the poor animals that lose their homes for use to simply drive our cars? I'm not one of those PITA PETA people (I freaking hunt a lot) but logging just simply makes me mad. It used to be beautiful country around my home and now it's ugly bare land everywhere from greedy loggers. Now converting land fill waste to usable fuel....that's a thought if it can be done efficiently. That's the problem though.....it usually requires more energy/fuel to be used and consumed to make said products though. Like WJM stated....very inefficient!
Looking forward to a little more info on the various set ups you have tuned on E85. Also on a side note, what injectors will a 255 lph pump support? I mean if you convert it over to cc/minute that is like 4200 cc/minute. So in theory if this were a perfect universe, they would support up to 1000cc injectors or a little more right?
The funny part is that we are on a site dedicated mostly to performance automobiles and people are talking about efficient use of fuel and energy...guess what a smart car or a scooter is a much more efficient mode of transportation than a WRX when we are talking about consumption and energy efficiency, but I would rather drive my WRX any day of the week!:fawk:
Hey, crashtke, I like what you're up to. The posts got dense. The motivation is good, and the process for getting there is good, but it felt to me like there were posts that were scattered with thoughts. Is there a recipe? What are the 3 steps to success? In the end, what does it cost? What's my mileage before and after. It's important that, in the US, ethanol is political. We're all about using this fuel madness as an opportunity to win the corn farmer's vote. What kind of flexibility do we have? If the next administration and congress took away the tax benefits for turning corn into alcohol, how much leeway do we have before we regret replacing fuel injectors? too many questions. Sorry DD
Not at all, the good part is that injectors are injectors. There would be no negative to running Sti pinks on a stage 2 car. Once they are tuned for it is done! The cost from what I have found is $100 for a walbro 255 pump, regulator is optional but that is $140+ misc fittings and the cost of injectors. It all seems to depend on what the cost of injectors...you can get Deatschwerks for $250 after the rebate, so call it $350 for all you would need provided you tune yourself. Gas mileage is going to drop a little. From everything I have seen, it is going to drop 2-4 mpg. This is going to vary depending on how much your foot is in the accelerator. But with the cost being around $1 cheaper per gallon, it makes up for that loss and then some. I plan on doing this regardless...for me it is just something I want to try. I guess I am always interested in trying new stuff. For me, I am just trying to figure out he logistics of this in terms of my future upgrades. If I could spend a bit more and get the injectors I need in the long term, I might do that...but I need to find out some more information first. One thing I am unsure of is the limitations of the AP to control injectors...I am not sure what size becomes an issue with idle and such.
a 255lph fuel pump will usually support about 600whp on most cars, Subarus seem to be in the 500-550whp range, 70% of that would be 385whp, thats more than enough for most Subarus if you have a 30R or bigger you are probably going to want to go to a twin pump setup. The fuel pump is really only releavant to overall fuel demand and not injector size. Matt Oh and my AEM for the 240 came in today so Ill get started tuning it tonight on pump gas and hopefully make the switch to E85 next week and then possibly E100 after that.
Cool deal, initially I am just going to go with a single. Once I convert over to the 6 speed and the 2.5 block with a 30r I guess I will have to start making some decisions. Also I found out some interesting information on the production of E85 using corn. The corn that is used to produce E85 is only feed grade corn. It is basically the rejected corn from the human crop and is meant only to feed pigs and such. After the ethanol is produced, they actually sell the corn mash back to the farms and the farmers are able to use it as feed still. When grain is used, it is also sold back to the food industry as "brewers grain," whatever that is. So it seems that the production of E85 does not prevent the use of the corn or grain from being used in the food industry or feed industry! Learn something new every day.
well I have a still, and apparently you can apply for an ATF permit to make X gallons of ethanol a year for personal vehicle consumption