The defacto guide to tuning your car for e85.

**SgtMarshal** · 10-25-2016

Originally Posted by Fivefingerdeathpunch

More fuel isn't going to help you, going richer is the opposite of what I would want to do with E85.

E85 is great at taking away heat, you should be able to lean the mixture out a little bit using E85.

I was just about to go and ask my question again, but you answered it. should I change anything other than the maf if I'm only going to run the 40%-50% ethanol blend?

**91parkave** · 10-25-2016

honestly don't know why you change your maf curve for e85 or any blend. your stoic is what's ****ed up and needs changing. but since 3800 members don't like stoic adjustments. ifr would be your quickest solution

**SgtMarshal** · 05-09-2017

has anyone tried emailing HP Tuners to get them to finish mapping the afr table so the "stoic method" can be used effectively?

and if I did just change the stoic, would I just change that one table? and if so, what would I put in?

**chrsmi1** · 05-09-2017

I emailed them to see about unlocking some other tables for it (fuel stuff). It's been two weeks and all I've got is a generic reply. So yeah.

**GTPpower** · 05-09-2017

Originally Posted by SgtMarshal

has anyone tried emailing HP Tuners to get them to finish mapping the afr table so the "stoic method" can be used effectively?

and if I did just change the stoic, would I just change that one table? and if so, what would I put in?

It won't work. You can literally put anything you want into that table, and the car will always correct it to 14.7 once the trims take over. Due to our o2 sensor, there is nothing you can do about it unless you run in open loop.

**SgtMarshal** · 06-01-2017

I read on this site that stochiometric for E70 is 10.69, so if I was running E70 that should be my target afr, correct?

I am adding a methanol kit, and AEM says to lean the mixture by 1 point, so in this case my target afr would be 11.7, correct?

any suggestions on where I should set the start psi for the methanol to start flowing and where I should set the full psi?

http://www.ecmtuning.com/wiki/e85fuel

http://aemelectronics.com/files/inst...ns/30-3300.pdf

**Fivefingerdeathpunch** · 06-01-2017

Read post above yours, it does not matter what you change stoich too, it will always correct it to 14.7.

If you tune in lambda you need not worry about stoich, because stoich is stoich is stoich no matter the fuel you run. If you stay on the AFR scale just aim for similar numbers as you do now.

**SgtMarshal** · 06-02-2017

When in pe mode, isn't it in open loop? And wouldn't it target the afr that's commanded for pe?

**GTPpower** · 06-02-2017

Not really....commanded is usually nowhere near actual, unless you spend the time tuning to get it there.

Keep your wideband calibrated for gas, and nothing changes. Shoot for 11.5 at wot. Then lean it out til you see knock. Or pulley down.

**SgtMarshal** · 06-06-2017

has anyone actually dyno tested different air fuel ratios of E85 to see what the different power levels are for the different ratios? I've been reading online and have found that E85 max power rich afr is like 6.429 and E85 max power lean is 7.8 while E85 stoich is 9.0078, so are we running our car's lean?

it would take a lot of fuel to hit those ratios, and the car would probably run really rich all the time.

**Fivefingerdeathpunch** · 06-06-2017

Why would it take anymore fuel?

I don't think you understand what is going on here. Just because the stoich ratio changes for the given fuel, doesn't mean it going to take a far richer commanded fuel number to achive your goals.

This is why tuning in lambda makes all this nonsense simple when using E85. Stoich is stoich no matter the fuel you are running. You'd be tuning it for somewhere between .75 and .85 lambda.

Because you are still using the gas scale on the wideband you have to think about it that way still. 6.429 commanded on E85 is like commanding 10.3 to 10.4 or so on the gas scale. That is still pretty rich. Going to the max lean on the E85 at 7.8 is like running upper 12's on the gas scale.

**GTPpower** · 06-06-2017

^^That.

Quit looking at posts where they are calibrating the sensor for e85. There are no benefits, and it will do nothing but confuse you.

**SgtMarshal** · 06-06-2017

this is what i've learned so far, correct me if I'm wrong: the wideband shows the same afr regardless of fuel used, so since the fuel used has been ethanol based the air fuel ratio will read richer than actual gasoline. The stochiometric ratio for E70 is 10.7, so that is what the air fuel ratio should be.

I do plan on giving it all a rest because it really is confusing, but if what I posted above is true, then I think i have a handle on it.

**Fivefingerdeathpunch** · 06-06-2017

If the wideband is setup to use the gas scale and you run E85, it's still going to show the stoich is around 14.7 and not 10.7.

**SgtMarshal** · 06-20-2017

what would you guys put for the cylinder gain if the ethanol was 90% content? I was thinking 1.31

**GTPpower** · 06-21-2017

I've always done 30% increase and let trims do the rest.

**SgtMarshal** · 08-23-2017

http://www.grandprixforums.net/threa...t=97autoxvette

using this method and targeting 9.8 in open loop, how close will that afr be to actual, and is it like the cylinder gain method where gas mileage is about 30% worse?

or is it a vehicle specific thing and everyone's car is different?

**GTPpower** · 08-23-2017

It'll depend on the car, but should be somewhat close.

But you are going out of your way to make this harder than it needs to be.

**BoostedPontiac** · 08-23-2017

Why not just change the ifr table and then ve and maf tune?

**SgtMarshal** · 08-24-2017

that's too much work. ifr table should be a set and forget deal. it's much easier to change the cylinder gain. I just want to try something different.