Let's get technical: Tuning the ECU for mpg
 

My approach to better fuel economy has been mainly to increase fuel efficiency.

Enough background, I'll get down to the meat.

Ok, basically your ECU is watching you. Well, not you, but your driving via sensors. It's taking in information and making educated guesses based on it.

I've been researching Nissan ECU's, but I'll try to keep this as broad as I can.

The main things your ECU is looking at to decide how much fuel to inject are a) RPM b) load. Load is calculated from sensor input (ie O2, MAF, MAP, etc.) Depending on engine conditions, the ECU will run in either open or closed loop mode.

Open loop is entered at WOT and at warm-up. Open loop uses fuel and timing values found in 'maps' in the ECU's memory. For a given load and rpm, the ECU decides the pulse width frequency of the injectors. There are only so many programmed rpm and load values, so when the actual values fall somewhere in between, the ECU's processor interpolates to find a happy medium between two known values. Open loop is more or less static (ie the ECU doesn't care how rich/lean the mixture is because it's not taking input from the O2 sensor.)

Closed loop is your friend. This is the mode in which the ECU utilizes the O2 sensors' voltage(s) to make fuel and timing decisions. Similar to the open loop, there are 'maps' for the ECU to read from for given rpm and load values. However, these values are 'difference' values rather than 'absolute' values. Difference values tell the ECU how much to alter the current setting and in which direction (positive or negative).

Closed loop sounds great, right? Well, it has potential. Ok, that's sort of a pun (voltage=potential difference). 99.999% of EFI cars use a narrow-band O2 sensor. The voltage ranges between 0 and 1 volt and it's probably the least accurate sensor on your car (outside of the 'No Oil Pressure' light I had on my Nissan or a 'Your engine is a pile of molten metal, pull over.' light.) In reality, the sensor is there to protect the engine from running lean. The values aren't accurate enough to clearly separate lean and rich. If it runs way rich, the ECU will usually cut back fuel until it's lean again, richen, lean, etc.

So what's the solution? Wideband. Much more accurate, but also more expensive. VW has begun using wideband O2 sensors in their vehicles. I don't believe they've matched the wideband's tech with the ECU's programming just yet, but it's definitely a step in the right direction.

I use the Innovate Motorsports LC1 wideband with my tuner.
It was $199 and I don't think that is bad for a wideband.
https://www.innovatemotorsports.com/products/lc1.php

I disagree with the idea that a narrow band sensor is less accurate. It is in fact very accurate, but over an extremely narrow range. This allows the computer to see conditions that are lean or rich very quickly - but with the caveat that it can't tell how rich or lean.

In other words, it's the difference between finding the vertical center of a bubble vs. the geographic center of a puddle. Both sensors will do it just fine, but the latter will tell you how far you are from it.

That said, I think one of the largest improvements in fuel economy can come from 'throttle pump' tuning. (The amount of fuel dumped in when the accelerator is initially depressed before the oxygen sensor can respond.) A generous amount of throttle pump will tend to make a motor more responsive and zippy to throttle increase, but it often does so by over-richening the mixture. The flip side is that response can fall flat if one attempts to hold it too lean.

I'm glad this discussion is taking place because this topic is where everybody seems to fall flat on their face.

No modification can really fool a modern (OBD2) ECU. There are too many checks and balances built into modern engine management to allow a backyard mechanic to make a tweak here and an adjustment there which results in consistent and long-term fuel savings.

That being said, going directly to the source of the trouble and modifying that will get you lots of options in both savings in fuel and increases in power. As has already been mentioned, OBD2 (anything from 1996 on) uses two different management strategies...open loop and closed loop.
Open loop uses a set of fuel curves and ignition curves which control the injector pulse width. The maps are 3 dimensional with the X axis typically being RPM, Y axis being load, and Z axis being either pulse width of the injector (for the fuel map) or ignition advance (ignition curve). Open loop is called upon when the engine is cold or at WOT.
Closed loop uses the oxygen sensors to compare actual oxygen content of the exhaust to a 3rd set of maps. These maps has various A/F ratios for different loads and throttle settings. The maps are referenced much the way the open loop utilizes the maps.
Narrow band vs. wide band is definitely a consideration for those of us who modify the stock injection computers, but as far as one being more efficient in a stock system versus another....you won't find a difference. Both are referencing stock maps to make their decision. ANY OEM wants to avoid warrantee returns as it cuts into the bottom line. We all know a rich engine is a happy engine (from a longevity standpoint), so most engines are programmed to run richer than stoich. My Pathfinder stock fuel curve (closed loop) often times asks the injectors to provide enough to maintain 12.5:1. This is a serious problem from an efficiency standpoint. I don't have any hard data to prove it, but I would bet Honda doesn't run their lean-burn series of engines any leaner than 14.7:1....they just run close to the line, and do it more often.
The code used to program OBD 2 is not universal and is proprietary to each car maker. The big 3 (Ford, GM, Chrysler) have released their programming code for many of their sports lines to tuners...this is why you can buy a handheld tuner for a Mustang, Camero, Corvette, etc. but not one for a Toyota, Nissan, or Honda.
The ONLY way to mess with the stock curves is to either do a piggyback unit or complete standalone. There is an interesting oxygen sensor interrupter made by www.eagle-research.com which supposedly fools the computer into thinking the oxygen sensor is reading rich, and leans out the mixture. I haven't used this at all, but when looking at the way the computer utilizes the oxygen sensor, it appears as though you could potentially do some harm to the engine when running under a high load condition. I would love to hear of some experience with this option.
I am installing a Greddy E-Manage Ultimate system into my truck. This system allows full control over fuel and ignition curves, and actually has two completely different maps which can be toggled between.
Stand alone systems are pretty serious business and I wouldn't personally recommend them for what we're all trying to accomplish here.

Any modifications to the fuel and ignition curves obviously are followed by the risk of detonation and engine damage. Its all well and good to tune the engine so it is running at stoich, but if provided with the proper additional hardware, and engine can run consistently and reliably for an indefinite period of time at upwards of 20:1. This would require water mist injection which should be easily set up....there are kits available for the turbo and supercharged crowd to control their detonation. At 20:1, you would be using roughly 55%-60% of the fuel which would be used at the stock fuel setting....

This is the direction all future modifications to an engine needs to go. Gone are the days of making a tweak with a screwdriver and realizing gains as a result. Its all about computers, sensors, and programs these days....

Spence

ECUs have been talked about quite a bit on GS over the year and months we've been around, and I used to do a lot with it...until I realized there really wasn't much to do with it. You can tune and this and that and pull more power out, but on a well designed engine you can't do much unless you've extensively modified things (at least on a honda, there is very little wiggle room for power or economy through ecu modification with stock equipment).

It may be different with a truck of course, but I would be wary of doing anything that will cost too much money expecting magnificent results. And also, I wouldn't run 20:1, poisoning the air is not worth a few mpg...

I leaned out be 1980 VW CIS injected engine and ran it 163k miles without problems - stock setting it ran 27mpg dead cold 0 degree winter or 80 degree summer and with some injector mixture adjustments by building up the "air cone" mass air flow sensor the mileage was up into the 37mpg range. Problems when you get into the 18 to one and higher start to show up at highway speeds but around town should not be a problem. It would be a real kick to get the xB to achieve 70-80 mpg by leaning out the A/F ratio on occasion. I think it is time for the dual A/F gauge order to be placed so I can see what is going on. Been feeling a little skipping lately at light throttle as I approace 14,000 miles - btw I now have 10,000+ miles on Synlube and all seems ok.

Ah yes....you're referring to Nitrogen Oxides. Though this is a very good point, the use of water injection negates the issue. Nitrogen oxide production increases as combustion temperatures rise. Water injection cools the incoming charge by a huge amount due to its latent heat of vaporization properties. As a result, you can run very lean, very advanced, and your EGT's will be lower than if you were running a stock fuel curve.
To comment on the 18:1 and above ratios being a problem at highway speeds, I think this would be more of an issue if you were to use that oxygen sensor signal modifier I referred to in my previous post. When playing with actual fuel and ignition curves, loads at various speeds (RPM's) can be compensated with a little more fuel (or ignition) if a little extra power is needed at a particular RPM. I think at the end of the day using water injection in conjunction with lean burn AND ignition advance would make for very comfortable cruising power under FE mode...
I agree that modifying an ECU without any other modifications is not very helpful....but as with anything, if you understand the whole system and the effects each variable has on every other variable, you can make significant improvements. Don't assume OEM engineers have designed everything perfectly. I work for an OEM and the design philosophy is based on dollars, not engineering.



Spence

Not only does Open Loop occur at startup and WOT, but also at closed throttle (CT? NT=no throttle?) when coasting at zero load.

Say I'm driving along the freeway in my Saturn, let off the gas, in gear, manual transmission, to take a rather long exit ramp. Or downhill. With zero throttle, load drops to zero and the ECU goes into Open Loop. Fuel usage shows well above the idle rate of 0.2 - 0.3 gallons/hour, but not as high as if I still had my foot on the gas. So the ECU is commanding the injectors to either shut off (fuel cut-off on decel - yeah! but SG doesn't know how to report it) or minimal injection to keep fuel trim from not leaning out too much.

Yeah we know about that because the ecu continues to calculate the injection of fuel all the time is registers on the SG but all indications are that there is no fuel being burned in my xB because on a rather long hill I see no temperature rise in the engine which does occur at those fuel burn rates normally. So it surbtracts from the trip MPH a little and throws off the gallons burned in the tank - by maybe a tenth of a gallon in 10 gallons 1%!!

Well I own an LC1 now. I have not installed it. Can I program one output near stock and one for say 17:1 and switch between the two with a toggle switch. Just thinking about it.

How do you intend to actually control the A/F ratio of your burn cycle with the wideband 02 controller? I was under the impression that the LC-1 could output an analog signal to a stand alone, piggyback, or datalog system, but couldn't by itself do anything for engine management....let me know if this isn't true, as it could be a very interesting alternative.

Spence

my volvo has a little screw you can turn on the mass air flow sensor to adjust the air/fuel ratio...

What year is the Volvo? The mass airflow should just be an input into the computer, along with that silly O2 sensor which will correct any attempts to lean out a mixture (for Nitrogen Oxide reduction purposes)....if its an older FI, than maybe this isn't the case. That would be cool... :)

Spence

Go to the Innovate web site. Go to support. You can print or read the manual. It is on page 17. I was sort of reading between the lines. It sure looks to me like there are instructions for connecting it to your ECM. I have two sensors and the second one is used for trimming so it might set a code if it never changes state. Another here said a simple circuit can take care of that.

Bear in mind I have not done this yet.

https://www.innovatemotorsports.com/support.php

A lot of Dodge guys have done some work with the ECU and "fooling" it to run a leaner mixture. What I've done in the past is add a variable resistor to the IAT circuit to fool the thing into thinking it was seeing a different temperature. In real cold weather (0 degrees) I could actually get the thing to stall from fuel starvation.

The primary use of it is to increase HP by tuning the mixture. But with high gas prices, one could also tune for mileage.

I have a LC-1 installed in my car and you can easily change lambda on the sensor to something other than 14.5:1. My car is way out of tune so the leanest my car can go normal cruising is 13:1 but I can set the ratio to 12:1 and the car happily adjusts the fuel up to reach that. I have it set at 14.5:1 right now but seeing as how it can't get that there is no point in me changing it.

Wiring it in the car is pretty simple, just switched power, ground, and the o2 signal wire. I already had all those under my hood so I didn't have to run any wires through the firewall to hook it up.

Won't be long before I have time to install the megasquirt into my car then I can tune it for anything I want to try :)

If you really want to run lean, consider changing computer systems. The two I like are Megasquirt which is a cheap, do it yourself system that allows the use of a wideband and is very cheap to buy in comparison to many aftermarket systems. Only bad thing is, it's batch fire injection although they are working on a sequential method. The other one I like is Big Stuff, which is more expensive but also offers sequential injection. With a wideband you can get an accurate measurement from 12:1 to 20:1 A/F ratios, and have total control over how and when.

Hope this helps.

Very interesting. So the LC-1 can actually output a modified signal to the ECU? This could be a very powerful tool to those looking to tune to a leaner burn condition. It must act in a similar (though seemingly much more advanced) manner to the unit provided by eagle research (see the link above). I have done lots of research on stand alone systems such as the Megasquirt. They all have their benefits and drawbacks. The biggest drawback I see with ALL stand alone systems is that they require the use of their own sensors. This means you can't just cut into the stock harness and hit the ground running....you actually need to convert the entire engine management system over to whatever the system of choice requires. This is a serious drawback for those of us wanting something that is nearly a plug-and-play setup. Megasquirt is an odd duck. Its entire system is based on "open source" knowledge and technology....from the board design all the way up to the system programming. I'm not an electrical engineer, and I know when I should count my losses and run. This is exactly what the Megasquirt would cause me to do! For those interested, do some research on the Greddy E-Manage Ultimate....its a nice compromise between an LC-1(I assume) and a full stand alone (such as Megasquirt).

Spence

There is a guy that is making a basically plug and play megasquirt that fits metro/swifts. The only thing you have to do is run a vacuum line to the computer. The rest just plugs in as is.

Hello! Interesting thread. I think I'll subscribe.

Wide-band sensors are nothing new - Honda has been using them for years. The '92-95 Civic VX, '96-05 Civic HX, '00-06 Insight and '01-05 Civic Hybrid all use wide band oxygen sensors to operate in lean-burn mode. The lean burn system is designed to go as high as 22:1 A/F ratio if the conditions are right.

The guy with the 30 mpg Explorer uses some kind of custom ECU programming to try to increase his gas mileage. If you are interested, you can search here for "30 mpg Explorer" and try to find the thread where I linked it, or just google "30 mpg ford explorer scuba quest" and you will find the Explorer board where he posts.

I was out of town for the weekend. I'm happy to see that there's some good discussion occurring.

Interesting stuff about the LC-1's ability to be 're-geared'. They're priced reasonably well, so the ability to adjust the output is icing on the cake (very good icing).

I didn't realize that Honda was using WBO2's, but it sure helps to explain why the prices were so high when I was checking for my friend's HX.

Another friend of mine has mentioned an MR2 that's running to different programs for race and economy. I'll see if I can get more info, but I remember being impressed when I heard it.

Here's how to get a dual image in the 1990-1994 Eclipse chip. Maybe the MR2 is similar? https://www.dsmchips.com/dualimage.html Usually one half of the chip has a tune suited for regular pump gas, and the second image is setup for race gas. This way you don't have to re-tune if you add race gas at the track. Just flip a switch.

Like it said in the Megasquirt link, there's not much reason to have a HP tune and a seperate economy tune since when you want economy, you're at light throttle. So tune the light throttle maps for economy. When you want power, you're at full throttle, so the full throttle maps are tuned for power.

Aha. Here it is. I found an old post I wrote about stuff that can be changed in the ECU to save gas. Each one is just a little thing, but it all adds up.

"This is just the stuff I'm doing with my ecu. The stock ecu in my car controls just about every aspect of how the motor runs, there are very few mechanical controls. This will be a shotgun approach, I'll list everything in my notes. Each one of these items can be changed to optimize FE and tailored to a drivers particular habits. It's up to each individual to examine their car to see if improvements can be made in each area.

Idle speed control (isc): regulated by a stepper motor, 0 steps is closed, 120 steps is fully open, 30 steps is base/normal.
-ECT based offset when starting to crank, added to base isc depending on ect. This is how high the engine revs when first started.
-Timer that counts down starting-to-crank isc offset, this is how quickly the revs drop to idle after being started.
-Starting to crank fuel enrichment aka choke. How much extra fuel is added when starting the motor.
-Starting to crank countdown timer used to decrease choke enrichment. Has two speeds; enrichment decreases quickly at first, then slower.
-Starting to crank timer threshold between quick and slow timer.
-Target idle speed based on ect. Lower your idle speed, especially when the engine is cold and running most rich.
-Rolling idle speed, isc steps added to base when car is moving. Also based on ECT, higher when cold.
-Threshold where car is considered moving/stopped.
-ISC offsets added to base if A/C is on, power steering pressure is up, and ? somthing else.
-Coasting fuel cutoff, cuts fuel when engine rpm is above threshold and throttle is closed. I lowered the threshold so I can coast longer in gear with the fuel off. A side benefit is that there is very little engine braking available at lower rpms, so I can keep the car in a higher gear and coast longer. Useful when EOC is not appropriate for the conditions.
-Accelleration enrichment fuel adder based on ECT, how quickly the throttle is opened, and a timer used to taper off accel enrich.
-Warmup temperature threshold for determining open loop vs. closed loop (31*C on my car), and warmup2 used for closed loop/cold engine enrichment vs. closed loop/fully warm engine (86*c).
-fuel trim update temp, based on ect. Below this temperature threshold the fuel trims are not updated.
-ECT based fuel enrichment table. Runs richer at colder temps, decreased to standard enrichment as airflow goes up.
-EGR solenoid duty cycle map, based on load and rpm. Adjust EGR use at individual rpm/load points. 56 datapoints.
-EGR solenoid modifyer based on ECT, less EGR at cooler engine temps.
-Rev limit. Fuel and ignition are cut off above this limit. Could be useful if someone is using weak valve springs?

-Ignition timing map, 192 points based on rpm and load. On my car there are a few areas on the map where timing is decreased in order to smooth the power delivery, such as when the turbo is spooling up. There is another area where timing is decreased to make the car feel more torquey, such as low load at 1000 to 1750 rpm. Standard theory is that timing should go up as rpm goes up, and timing should go down as load increases. But at low load/low rpm it starts with low timing, then timing increases as load increases from load level 1 (lightest load) to level 4 (out of 12 levels). The difference is significant, about 6 degrees less timing at light load vs. load level 4. The stock timing map 'FEELS' nice, power surges as you step on the throttle. I changed the timing in that area so it's flat, no increase or decrease from level 1 through 4, and I found I can back off the throttle much farther once up to speed. In other words, I'm using less throttle to maintain 35mph.

-Ign timing corrections based on ECT. timing is increased below19*F.
-Ign timing corrections based on air temp. The stock map decreases timing at temps above 100*F and below 48*F. I changed it to increase timing between 73* and 19*F, with a max increase of one degree at 48*F. and tapering off above and below that temp. My change was based on the theory that colder air lowers the octane requirement of the fuel. It's also possible that the engineers might have reduced timing in this area so the power would not change with temp since their buyers might complain when the weather warms up that power is lacking. Just a thought.
-Open loop fuel map. 168 points based on rpm and load. Specifies a target A/F ratio depending on the rpm and load level. Only used during open loop.
-Open/Closed loop thresholds based on rpm/throttle position. Changes the point where open loop is used. I raised the thresholds so I can dip into the throttle at low rpm without going into open loop, and so I can stay in closed loop at higher rpm.
-Open/Closed loop thresholds based on rpm/airflow. Same as above, try to stay in closed loop longer.
- A/C on/off threshold based on throttle position. WOT shuts off A/C. Lower the threshold so A/C is off during anything greater than light accelleration.
-Closed loop O2 feedback cycling speed. How quickly the O2 sensor cycles up/down.
-O2 feedback stoich trigger. Stock is set to .5 volts. Can be changed in .02V increments, may affect emmissions.
-O2 feedback increase/ decrease values,wide range. How much fuel is added/ removed from base fuel calculation in order to get the O2 sensor cycling.
A wide range is used to help find .5v and center the short term trim. Used for the first 4 seconds each time after returning to closed loop.
-O2 feedback increase/decrease values, narrow range, used after 4 seconds to increase O2 sensor cycling speed and limit wide excursions from .5v Based on airflow and rpm. Different tables are used depending on Federal or California market.
-O2 feedback timer. Stock is set to 4 seconds. Whenever the throttle goes from closed to open the wide range O2 cycling is used for the first 4 seconds, then narrow range cycling kicks in. This can be changed to reduce the ammount of time spent in wide range cycling. May improve emmissions.
-Dash pot. Timer used to decrease fuel gradually when throttle is closed. Helps smooth the transition between open to closed throttle. Stock timer is .75 seconds, ie fuel stays on for .75 seconds after throttle is closed.

All of the above is adjustable simply by changing a number in the hex code.

OK I think that's it for the stock stuff that could be adjusted to improve FE. There are also changes that can be made to match any modifications to the vehicle, such as different fuel pressure, different size injectors, different or modified airflow sensor. These help keep the car running optimally with other hardware."

And then there's Multi stage Lean Burn Code. Yeah, this is more than just a few changes, but once you open up the box, there's no going back!

This guy knows his Hex, AND he is working with an OBD1 computer. OBD2 doesn't allow you to change variables in the EEPROM, and as mentioned earlier, all the Import manufacturers are using proprietary code to control their machines. All this being said, IF you are running an OBD 1 car (pre-1996) AND you are at peace with the programming gods, than this puts you many steps ahead of the rest of us who faint at the sight of code...

Spence

When working with this type of modifications remember to add in a thermocouple in the manifold to monitor temps.

My 84 Turbo has Bosch CIS with the 'little screw'.

I found this post while searching for some info on the P07 ignition maps. I was at the dyno this past weekend with my D15Z1 (has modifications) getting the P28 ECU tuned (burnable chip) and was chatting about a fully controllable ECU. I was just wondering how agressive/safe Honda was with the P07 ignition maps under lean burn conditions.

If I were to use a "full control" ECU it would be nice to have a good starting point for the ignition maps (lean and normal burn).

Re: Let's get technical: Tuning the ECU for mpg
 

I just raised the closed loop threshold (throttle position x rpm) for all values on my D16Z6 P28 ECU with chrome, I'm hoping to get better mileage as I'm a hard driver but I usually keep my foot below WOT. I changed the threshold values to about 80%. That's an idea I just had, so I'll tell you if I get bad mileage which I think is unlikely to occur as when I had a wideband, the stock basemap produced 12.5 AFR when in open loop.

Re: Let's get technical: Tuning the ECU for mpg
 

I hate closed loop. :thumbdown:

Have you tried running only open loop and build your own fuel/ign. maps. You can dial your tune in way better then stock when running in closed loop as long as you have a wideband for reference. Major gains can be made over stock by running in open loop with a good map.

Re: Let's get technical: Tuning the ECU for mpg
 

I sold my wideband some time ago, but the point in raising the tps threshold is that it would switch into open loop only when I wanted performance (as I do want performance sometimes). Also as stock ecu does not accept 2 maps running at the same time (one map for performance and the other for economy) which is what I'd really want.
Apparently I had no significant improvement in raising the TPS, but I don't know whether it did or it didn't work. I've got stuck into HUGE traffic jams these days (12 miles in 1,5 hour).

Re: Let's get technical: Tuning the ECU for mpg
 

You can have your performance and economy too. All you have to do is run the engine lean in light load and normal in mid to heavy load. All of this is of course based on your MAP sensor.

Re: Let's get technical: Tuning the ECU for mpg
 

Wide band tune for both FE and power. I used closed loop up to 80kpa.
https://www.fuelly.com/attachments/fo...21fea2bd2f.jpg

Re: Let's get technical: Tuning the ECU for mpg
 

Heres my low-cam fuel map.
https://www.fuelly.com/attachments/fo...71136294ed.jpg
These are raw numbers that I set by using a wide-band and real time tuning. All in tuned in open loop.

Re: Let's get technical: Tuning the ECU for mpg
 

That's great guys! Now I regret that I sold my wideband :(

Re: Let's get technical: Tuning the ECU for mpg
 

but I got 32 mpg cruising at 65mph on a trip last weekend. It got a bit better and brazilian pump gas is 25% ethanol.

Re: Let's get technical: Tuning the ECU for mpg
 

What part of Brazil are you from?

Eventually I think the United States will be around 25% ethanol also.

Re: Let's get technical: Tuning the ECU for mpg
 

I'm sorry, I said it was 32mpg, but it was 36mpg (15km/l which is my native measure lol, google calculator just corrected me)
I'm from Sao Paulo, but that % applies throughout the country.
Some days ago I ran on 70% ethanol with no problem, just increased the fuel pressure. I kept some of the mods I had when it was turbocharged with E100 setup so I can do that safely now.

Re: Let's get technical: Tuning the ECU for mpg
 

That's pretty good fuel mileage considering your speed and ethanol amount.

Also sounds like you have major traffic in Sao Paulo. I heard that the traffic is so bad that you have helicopter taxi's.

So most of your ethanol comes from sugar cane feed stock is that correct? Whats your price on ethanol there?

Sometimes I run E85 in my Talon for performance reasons. Its a very nice fuel for making great power at a low cost. One of my future builds will be a 800+ WHP Honda that will get 50mpg and E98 will be the fuel of choice for the performance side of things.

Re: Let's get technical: Tuning the ECU for mpg
 

Right now, ethanol is expensive, $3.5/gal (pump gas is $5.2/gal) it's not worth the warm-up time. In some months, $2.2/gal is the cheapest you can get. Pump gas has little to no change in price because the govt fixes its price to support the consumer price index. The break-even point we use when chosing the fuel is 0,7*GAS<=>1*ETH, so there's little saving in using ethanol right now. Also, 99% of the new cars are flex-fuel.
All of the ethanol here comes from sugarcane, the harvest excess is sold as sugar and vice-versa depending on international sugar price and demand.
It's the first choice of all tuners I know because it has bigger margin for errors regarding detonation and easily produces a few more HP.
It will be great to see your honda project :thumbup:. Hondas are the best when you want FE and performance.
Many people add ethanol to the gas tank for passing the smog check.
A chopper trip is not that expensive when you think about the time you'd spend stucked. When it rains it's common to average <10mph. 15-20mph on any other day.