The equipment and knowledgebase are now available to have a true flex fuel Evo with the stock ECU. Here's the laundry list.

- Flex fuel detection: merkzu has identified a flex fuel sensor (GM flex fuel sensor) and a company that is making a processor to read the flex fuel sensor and convert the ethanol content sensor signal from a frequency to a 0-5V analog signal. The processor also includes a gauge to display ethanol content

https://www.evolutionm.net/forums/sh...d.php?t=305253

- With some help from Jack of Trades, I've identified an unused ADC (analog-digital-converter) input on the ECU of all Evo 8s and Evo9s. This input will allow the ECU to read the 0-5V signal produced by the flex fuel sensor system:

https://www.evolutionm.net/forums/sh...d.php?t=314779

- tephra has begun writing a patch that will eventually allow interpolation between two sets of maps (one for pump gas and one for E85/98) using the ethanol content signal. v1 of the patch is aimed more at meth users as a failsafe, but it can be used for manual map switching as well. A later version of the patch will incorporate interpolation between pump gas and E85 maps using the 0-5V signal produced by the flex fuel sensing hardware:

https://www.evolutionm.net/forums/sh...d.php?t=314505

I'm hoping that either myself or merkzu will have a working setup in a few months...

 

Truly amazing, really looking forward to this. Of course I'm assuming you still have to tune for an e85 map correct? All this will allow is automatic switching of the map (v2) when the sensor senses ethanol in the tank?

 

Yes, the car will have to be tuned for pump gas and E85, and then the sensor will allow the ECU to interpolate between the two sets of maps based on the ethanol content in the fuel. It remains to be seen whether a linear interpolation will suffice or whether some curved interpolation scheme may be necessary.

 

Would it not be easier to tune your low octane map for 93 and your high octane map for E85/98 and just adjust the boost? I love the idea of it automatically switching, but if your boost isn't changing then do you really get to see the full benefit of using E85 over 93?

 

Its boost and timing that can be increased with E85. Tuning the low octane maps for pump gas and the high octane maps for E85 would not be a good idea. The ECU would then be deciding based on knock rather than fuel composition. It takes a fair bit of knock for the ECU to fully transition to the low octane map. It would probably destroy the engine pretty rapidly.

The automatic map switching based on fuel composition will be able to adjust the ECU boost control maps as well, so if the car is setup for ECU-based boost control, then not only can timing/fuel be adjusted based on fuel composition, but also boost.

 

eagerly waiting to see how this turns out. I am very interested in moving to E85 but there is literally 1 station in MA.

 

Any thoughts on how best to handle things if you are not controlling boost via the ECU? I don't think there's a such thing as an EBC that can interpolate between 2 boost settings, is there? I know the AVC-R can switch between boost maps based on a digital input, and I guess a pretty simple circuit could turn the 0-5V signal into a digital signal that switches at an adjustable threshold, but a smooth adjustment would be much cooler of course.

Keep us posted; this is very exciting.

 

+1 sounds like a great Spring conversion project

 

I'm totally in!! E85 is 2 bucks a gallon by me...

Subscribed!!

Cheers-
Erich

 

mrfred, aren't you in the NW? where will you get e85?

I would like to do this too, but I can't drive to a source and get home(just about)

 

One of the few E85 stations in the state is in my town. 3 min drive from my house. I lucked out. Its $3/gal though!

 

i have a station 1 min from my work. I can't wait till this is ready.

 

I've got like 5 or 6 stations by my house, but they are all like $2.69/gallon.
I thought this crap was supposed to be like $2.00/gallon.

Side Note: I've been putting like 2 to 2 1/2 gallons of E85 in my regular tank of gas, and I must say, you can feel how much more crisp the car reacts. My theory is that it is leaning out the fuel, therefore our car is not running as rich.

A little more air goes a long way!

 

One thing. If you've been running pump gas then go to fill up on E85, you still have some gas left in your tank so your mixture will essentially be something like E70. But the more you continue to fill up E85 more closer you get to true E85.

This setup that's in development is for automatically switching between two different map groups right? There is no interpolation going on between the two maps? So when tuning your maps I'd think you don't want an E85 map and a pump gas map, more like E20 and E70 maps. This is of course if you'll be switching fuels often.

You bastards are lucky you have stations near you. My nearest is like 1 hour away. Don't even know if it's available to public.

 

Automatic switching between two sets of maps with no interpolation will be ready relatively soon. Interpolation is a bit further down the road. Its going to depend on how much time that tephra has to work on this.