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12P with flex fuel would take the cake I say that'd be awesome!

I have split this topic, but it messed up the order of the first post. Anyway, can discuss the options of 12P and getting a flex sensor working on it.

Output of the sensor is a square wave that varies in frequency between 50-150Hz indicating 0-100 % of ethanol. It also varies the PW from 1-5 ms to indicate fuel temperature for -40 to 125 DegC. Getting the signal in to the ECU would need some thought as well. There are a few ways so will list them later when I have checked out the options. Some more info on the sensors can be found here .. http://www.megamanual.com/flexfuel.htm


In terms of the code there are heaps of ways to do this. Some are...
Option 1 - The simplest way, fuel correction only. Read the flex sensor to get a 0-100% ethanol value then use that to modify the fuel output PW. Simple and crude.
Option 2 - [most likely] Read the flex sensor to get a 0-100% ethanol value. Use this as a lookup in a table that outputs a correction value for fuel PW (either act on target AFR or the final PW) and a second one for spark % offset. This means you can fine tune the fuel and spark - ie with 50% ethanol from the sensor, lookup a table which has say 46% correction with that ethanol value and apply it to the fuel.
Option 3 - The ultimate. Read the flex sensor to get a 0-100% ethanol value. Use this as a lookup in a table that outputs a % factor to interpolate between map A and map B tables. Have a factor for fuel and a factor for spark. This is most likely going to overload the CPU as it means double the lookups for many items (have to lookup the map a and map b item and then calc the % factor between the values).


They all require RAM which the 808 does not have any spare of when running 12P. I will list a few things that could be removed from 12P and the RAM requirements later. Can then have a poll on it

There's a few features I don't use but I can't speak for all. I've never used boost or any map b features.

Maybe an option between Having Map B features of flex fuel?

i know i use pretty much everything, map switching, flex tables, boost tables

TdracerTd wrote:Maybe an option between Having Map B features of flex fuel?

I coud live with that. One thing I noticed on 11P is the single idle spark advance tabe. Not sure how much room it would create but a possibility. I do see the advantage of map b tables and they do seem to be popular. Is the map b BPC popular? If you're going to the trouble of changing injectors maybe you could burn or flash another cal too.

I have a feeling mapB doesnt use much memory at all. we are talking no free ram here. (808 ram is measured in bytes lol it has less than 1k ram. ) mapB takes up lots of cal space but thats not what we are running out of.

it will be more like kill off VE learn or one out of the 4 flex tables, or one of the extra inputs or something like that. mapB probably only uses 1 bit of ram. (map a or b switch) or 1 byte to log the a/d input.

if we want to collectively decide to kill off something in favour of something else, maybe VL400 can list out each custom feature and how much ram each use, and we can collectively vote out the features nobody uses?

Ok thanks for clearing that up. That side of things is not my area at all.
Say if a flex fuel version of 12P could be made. And the flex sensor was to be connected to the logger. Maybe the wideband could be wired to the logger too and lose that feature from the ecu. One less input and some code and ram space coud be freed up.

So to run flex fuel you woud need a logger and wire the flex fuel sensor and wideband to that.
Just throwing ideas around.

Only problems not everyone has a logger but they do want to run a flex fuel system better off taking out one 1 or 2 of the flex tables

Assuming 12P could be modified to work with a Flex Fuel sensor, what outcome ultimately would it be capable of?

Correct me if I'm mistaken but current flex fuel vehicles will deal with anything from running 100% of the time on the cheapest ULP91 right through to running 100% of the time on straight E85 as well as any mixed ratio between ULP & E85.

Assuming a wideband was permanently installed could 12P operate correctly under all these conditions?