Evilutiondreamz

iTrader: (1)

Love this

Jp7

iTrader: (11)

I don't think people understand what true FLEXFUEL means

flex fuel is any mixture between e85 and e10

if you are tuned for e85, your car is not flexfuel, even if you have maps for both gas and e85

flexfuel cars can adapt the tune (interpolate between mixtures) anywhere between e85 and e10

if you are not interpolating like this, your car is not flexfuel.

VanduzerWilliam

iTrader: (2)

"Flexible fuel vehicles (FFVs) are designed to run on gasoline or a blend of up to 85% ethanol (E85). Except for a few engine and fuel system modifications, they are identical to gasoline-only models. FFVs experience no loss in performance when operating on E85. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 25-30% fewer miles per gallon when fueled with E85.1"

/ragequit

Jp7

iTrader: (11)

but you can't run on up to 85% ethanol unless you have an ecu configured to run E85, and E80, E75, E70, E60.....E40....E30....(... all the way down to E10...)

The key word in your post is "BLEND". Chosing between E85 and E10 is not a blend.

Try running half a tank E80 and half E10 - your ECU will not be able to compensate and just adjust the fuel trims - unless you have the tephamod (which I understand is still in development) it can't fully compensate.

The idea of flex fuel is to compensate for any mixture between E85 and E10.

Each mixture beween E85 and E10 has a different stoich point and your ECU can't compensate without interpolating (the idea of the tephamod)

modern cars (which the IX and VII are not!) use a wideband to monitor the exact lambda and use that to compensate (no need for a flex fuel sensor).. Our IX and VIII's do not have this, they also do not have a flex fuel sensor.

Our ECUs use a simple old-school switching narrowband. Like the 3 little bears story, the pourage is too hot or too cold.. It see's switching and not when it is "just right".

illogicalmind

What about the grey area of, I can make tunes for different percentages of Ethanol mixture and just flash my ECU whenever I have to? It's not automatic, but still a Flex Fuel Vehicle since it has the hardware to adapt to the fuel mix?

Jp7

iTrader: (11)

Your bastardizing the word FLEX in FLEX fuel.

The basic concept of FLEXFUEL is that it's flexible. Let's face it, joe-public does not drain the tank on his family vehicle when he goes from E10 gasoline to E85. He simply fills up his tank. This leaves manufacturers forcing to cope with any mixture of Ethanol/Gasoline. With todays ECUS that use widebands to monitor fuel this is not a big engineering problem.

For our cars (IX and VIII) the ECU is very primative, say 1990's primitive. There are plenty of people on this website that understand the ECU better than I do but my understanding is that the ECU has a limited range of "trimming" (compensation) it can do when the sensors detect an abnormal situation. My IX is tuned for E85 and I specifically was told by the tuner I should drain the tank completely when switching fuels. If the ecu tries to trim the maps out of an "acceptable" range it will throw codes (lean or rich).

For the IX and VIII to be completely flex fuel the software needs to be developed to change ignition timing, fuel pulse-width, boost and mivec (if you have it). This is going to require hardware for boost since most of us run MBC's as well. I suppose there may be some way to do this with an EBC.

From my understanding there is a tephramod in the works to do this but it's not fully developed. Trust me I would love to have this as well. It's an exciting prospect but calling our cars "flexfuel" at this point is a little premature.

heel2toe

iTrader: (41)

Jp7 You are absolutely right that for the most part our evos are not a true flexfuel car. Without a content sensor and the ability for the ecu to automatically interpolate between various maps it is just not a flexfuel vehicle end of story.

However, when I started this group buy I was well aware of that. But I don't claim to drive a flexfuel vehicle. Sure I have an awesome badge now but my intent was to deter pesky gas station employees who would give me a hard time filling up since my car wasn't a flexfuel vehicle.

Jp7

iTrader: (11)

I apologize deeply for getting sidetracked in a for sale thread, I should behave better.

I have a warning sticker on my fuel door for that same reason "use E85 only"

at least you get some easy bumps!

illogicalmind

I just ordered a badge, because I like the grey area idea of i can tune it out if for some dumb reason I had to fill with 93 without emptying the tank. Your trims can go 12.5 + 25% short, so you could potentially run closed loop with a bad mixture. I won't, but you "could".

But I do want to point out that "Flex Fuel" vehicles say in the manual to run the tank down to empty as possible. Because they aren't very good at interpolating it either.

We rented a 2013 minivan. Put E85 in it just because we could. When I switched it back to 87, the car ran **** awful for about 3 days, which is where it was almost out of gas again anyway. It took almost our 1100 mile drive back home to get back to 26mpg on 87. And still had a studder when we returned it. Didn't seem that Flexible...

I do agree though with heel2toe, E85 station attendants around here look at me funny when they see my car. And are reluctant to let me. One kid so far laughed and knew what I was doing.