2018 Yukon Denali Flex Fuel?

[Shangaipaddles]

if you have flex fuel it will say so on the fuel filler cap/door and you will have the flex fuel rpo code in your rpo list.
they basically only put it on some 2015/2016 then pretty none there after, but you could get lucky. otherwise you can get a decent plug n play kit and just have it turned on in a tune.
this kit should also fit the suv's

2014-2019 Chevrolet Silverado 1500 Lethal Garage Flex Fuel Kit

Our custom E85 Flex Fuel kit for the 15-19 Chevrolet Silverado with a 5.3L or 6.2L engine, is just what you need for more power, savings on fuel costs, and a better smelling ride... (Okay that last one is subjective). PLEASE! Verify the harness plug location on your vehicle before purchasing...

www.lethalgarage.com

That's what I believed to be true as well, which is why I was confused when the AutoSync was showing me ethanol content. I've found a kit that I'll use if I need to, but would be cool not to spend the extra money if I don't have to. We'll see what happens when I put the non oxy in and if the reading changes.

 

[B-train]

Are you looking to run strictly E85? If not, I would assume you can run up to 50% without any problems. I know the 6.0L engines from 2015 up could run up to 50% ethanol blend right from the factory.

I've done a few tests with my 2017 6.2L, non flex fuel, and it handles a blend up to 50% just fine. No lights or weird running. I did notice that at the 50% range, it seemed like it may have run out of its programming limitations for fuel delivery.

This was a blend of 87 and E85. From what I've seen on both yukons, 08, 17, is that they seem to really like a 20-25% blend of 87 and E85. The power is there due to higher octane, and the mileage doesn't seem to suffer too much. Just an idea.

 

[Doubeleive]

That's what I believed to be true as well, which is why I was confused when the AutoSync was showing me ethanol content. I've found a kit that I'll use if I need to, but would be cool not to spend the extra money if I don't have to. We'll see what happens when I put the non oxy in and if the reading changes.

a lot of gas is e10 which is why

 

[Shangaipaddles]

Are you looking to run strictly E85? If not, I would assume you can run up to 50% without any problems. I know the 6.0L engines from 2015 up could run up to 50% ethanol blend right from the factory.

I've done a few tests with my 2017 6.2L, non flex fuel, and it handles a blend up to 50% just fine. No lights or weird running. I did notice that at the 50% range, it seemed like it may have run out of its programming limitations for fuel delivery.

This was a blend of 87 and E85. From what I've seen on both yukons, 08, 17, is that they seem to really like a 20-25% blend of 87 and E85. The power is there due to higher octane, and the mileage doesn't seem to suffer too much. Just an idea.

Not strictly e85, but want to run any combo of e85 and 93 depending on what is available.

a lot of gas is e10 which is why

Correct, but my truck shouldn’t be able to sense the alcohol content without a sensor.

 

[Doubeleive]

Not strictly e85, but want to run any combo of e85 and 93 depending on what is available.

Correct, but my truck shouldn’t be able to sense the alcohol content without a sensor.

They all detect/show the 10% without a sensor as far I know, I could be wrong

 

[Fless]

Many of these later models -- at least the GMT900s -- don't have a physical alcohol sensor -- it's calculated by the engine computer software, based on fuel trim tables.

Are they back to putting sensors in the later models?

 

[Shangaipaddles]

Many of these later models -- at least the GMT900s -- don't have a physical alcohol sensor -- it's calculated by the engine computer software, based on fuel trim tables.

Are they back to putting sensors in the later models?

Well that's interesting. That doesn't seem like a very reliable way to measure it. So if I fill with non oxy and it reads as 0, I still may not have a sensor, but it can sense the alcohol? Not sure I'd want to run full e85 that way.

 

[k_arnold72]

Hmm, ok. Thanks. I think my next move will be to fill up with non oxy gas and see if the reading changes. Maybe 9% is just a default value and it’s not actually reading? I still have 3/4 of a tank, so it’ll be a few days, but I‘ll report back.

Like the guys have suggested, maybe try a blend instead of filling all the way up. Just to see if that reading changes. Quarter tank of e85 should be enough to affect the percentage without being detrimental to drivability.

 

[Shangaipaddles]

Like the guys have suggested, maybe try a blend instead of filling all the way up. Just to see if that reading changes. Quarter tank of e85 should be enough to affect the percentage without being detrimental to drivability.

I’d feel more comfortable going lower on the ethanol than higher until we know if it’s reading correctly. I don’t want to run more ethanol than 10% until it’s tuned for it.

 

[petethepug]

Glad to see you got the a/s. Did you get it to turn off the AFM?

The 2018 Tahoe & Burb 5.3L are flex fuel so it’s still a thing. I almost crab’d myself when I saw a lady filling up a Gen 5 with e85 at the gas station. I didn’t know they still equipped them that late.

It shows the 6.2L didn’t get e85 though. It can be done with a kit I’ve seen on the web. If you have any emission or drive train warranty left be sure to remove the a/s from the truck? Some of the old skool dealership employees that wear tin foil hats are scared shipless of anything without a GM logo.