I'm Ryan Woody with Holley EFI and today we are going to talk about flex fuel.
Pretty much everything I'm going to go over is in the help contents under the V4 software
update overview.
Down at the end is an appendix that covers Flex Fuel capability.
So if you want to reference that as well if you can't get to the video, you can look there.
The first thing you need to do is set up a flex fuel sensor, which will be in input,
you can title it whatever you want.
It will be a digital speed frequency and it will be GM flex fuel in the drop down.
So after that, all you do is you go and you add an advanced ICF to your tune if you do
not have one.
Then the first thing you do is you set up a fuel modifier and you use a fuel flow multiplier,
depending on your tune, either use a VE based or a fuel flow multiplier.
The fuel flow multiplier multiples the fuel volume on everything in the tune, including
cranking, AE fuel, all of it.
So this will correct the fueling everywhere.
The next thing to do is to select the flex fuel sensor to reference and there you have
at the bottom your flex fuel, your ethanol percent from 0-100.
Now the baseline in the help file goes from 0-34 percent and that assumes that you have
built your base tune off of 100 percent gasoline.
A lot of times that doesn't actually happen so you'll end up taking the S curve and offsetting
it for whatever your base fuel ethanol level was.
You know most of the time you'll have somewhere between 10 and 15 percent ethanol and you'll
just use the sensor during your tuning to read that and then whatever that point is,
you know, let's say you have 20 percent ethanol is where you are at for all of your base tune,
what you'd do is offset this entire curve by 6.8 because of that because that is actually
your real baseline, your zero point.
So you highlight the whole thing, offset minus 6.8 and now you're entire curve is accurate
based on a base tune of E20 fuel.
The next thing that you do is, so you are doing this because you want to be able to
dump in E85 so what you do is you want to be able to add boost, add fuel, add timing,
whatever you want to your tune between the two settings.
So the next thing you can do is set up a, if it's boosted you can set up a boost offset
based on the same things, table type will be a boost offset, your X axis would be a
flex fuel sensor, whatever you have titled it, and from there based on your ethanol percent
you can just add boost, so you want to add five pounds at 60 percent ethanol, it's really
that easy, you just pick your tables for however you want, you can do whatever you want based
on the ethanol percent, another thing that you may want to do is an AFR offset.
Again you just set your X-axis for whatever you are using, in this case, the flex fuel
sensor and the table type to whatever you want to modify.
So the flex fuel sensors at the bottom, ethanol percent and your new target air-fuel ratio
is here.
Now this one, I'm showing it in a 1D table, really you probably want to do it in a 2D
table on this one, you know this is offsetting it at all times so any time your ethanol percent
is above 27, in this case, it will start modifying it.
Really you'd want to do this one as a 2D table and sort of mimic your actual target.
You'd set up your table as an AFR offset due to target air-fuel ratio offset.
Make your X axis your ethanol percent, your Y axis boost effectively and then you have
your table for how much you want to offset your boost.
You may want to allow an extra two points richer here and fade it back to no richer
down here and same over here and then same thing with the timing offset.
So you set up a table type as timing offset, X-axis as your ethanol percent, your Y axis
as boost and you do the same thing, you can offset your timing based on ethanol percent
and boost.
You can also use other things, you can use RPM and flex-fuel percent, it's really up
to you how you want to utilize the advanced tables for anything, in this case, flex fuel,
I mean there's, we don't lock you into any specific way to do this.
So really that's all there is to flex fuel and EFI with us, it's that simple.
Thanks for tuning in to Holley tech tips, be sure to let us know if you have any ideas
for future videos, I'm Ryan Woody, have a great day.