2018 Yukon Denali Flex Fuel?

[Shangaipaddles]

Hi, been lurking for awhile but first time posting. I have a 2018 GMC Yukon Denali with 92,000 miles. I just installed the AutoSync device from BTDieselWorks and going through the various pages. Under the powertrain data page, where it lists things like MAP vacuum, engine load, ECT, and the like, there is a value for ethanol, currently showing 9%.
I was under the impression the 15/16 probably had the sensor installed but the fuel files weren’t active, and the 17+ vehicles didn’t have the sensor. But this leads me to believe otherwise? Does anyone have verification that an 18 6.2 has the flex fuel sensor from the factory? Where would the sensor be located so I can visually confirm?
Been learning a lot from here, hope to be able to give back at some point.
Thanks!
_Kevin

 

[B-train]

I've seen some YouTube videos on the topic for newer GM stuff and I thought it was along the driver side frame rail with the fuel line. It has a 2 or 3 wire connector that goes to it as well. Probably somewhere in the vicinity of the fuel tank/cross member area.

 

[k_arnold72]

My 18 premier 6.2 did not have the sensor, but did have the wire harness in place with a dummy plug capping it off. I got an oem sensor(13507129) and a short piece of fuel line(from a 06 GTO, Russell 651121) and installed them near the fuel tank. My research led me to an exploded diagram of a flex vs non flex fuel system that showed them to be pretty similar except for the sensor.

Enabling the settings in the ecu is where I last left off before life made me pause any mods. Are you saying that your device allows you to enable the ecu to read and adjust for alcohol content? If so that's exactly what I've been looking for. Till now, hptuners seemed to be the only way, but that's overkill for my needs.

 

[Shangaipaddles]

I've seen some YouTube videos on the topic for newer GM stuff and I thought it was along the driver side frame rail with the fuel line. It has a 2 or 3 wire connector that goes to it as well. Probably somewhere in the vicinity of the fuel tank/cross member area.

Ok, thanks. I’ll stick my head under there tonight after work and see if I can find anything.

My 18 premier 6.2 did not have the sensor, but did have the wire harness in place with a dummy plug capping it off. I got an oem sensor(13507129) and a short piece of fuel line(from a 06 GTO, Russell 651121) and installed them near the fuel tank. My research led me to an exploded diagram of a flex vs non flex fuel system that showed them to be pretty similar except for the sensor.

Enabling the settings in the ecu is where I last left off before life made me pause any mods. Are you saying that your device allows you to enable the ecu to read and adjust for alcohol content? If so that's exactly what I've been looking for. Till now, hptuners seemed to be the only way, but that's overkill for my needs.

No, this device is only monitoring and displaying engine data, you can’t tune with it. You can tune the body control module, radio and hvac, and instrument cluster with it though. AutoSync

 

[Shangaipaddles]

Well I found a sensor, but it’s not what I expected. Does anyone know what this sensor is? I didn’t see anything else in-line under the truck, though the lines go above the fuel tank. But I wouldn’t think they’d put the sensor there.

 

[k_arnold72]

Well I found a sensor, but it’s not what I expected. Does anyone know what this sensor is? I didn’t see anything else in-line under the truck, though the lines go above the fuel tank. But I wouldn’t think they’d put the sensor there.

That short piece of fuel line is what you replace with the in-line flex fuel sensor. Looks like this. I don't know what that other sensor is though.

 

[Shangaipaddles]

That short piece of fuel line is what you replace with the in-line flex fuel sensor. Looks like this. I don't know what that other sensor is though.

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.

 

[B-train]

It looks like you have it. The fuel line looks to have the sensor with the 2 wire connector plugged in. Maybe I'm wrong, but it looks complete. Maybe it's a dummy placeholder?

 

[Shangaipaddles]

It looks like you have it. The fuel line looks to have the sensor with the 2 wire connector plugged in. Maybe I'm wrong, but it looks complete. Maybe it's a dummy placeholder?

I saw the wiring going to the sensor, but I expected the sensor to be more like a T fitting, not just a bung. I guess we’ll see when I put the non oxy in if my reading changes. Would be nice to only need a tune and not buy the flex sensor stuff.

 

[Doubeleive]

I saw the wiring going to the sensor, but I expected the sensor to be more like a T fitting, not just a bung. I guess we’ll see when I put the non oxy in if my reading changes. Would be nice to only need a tune and not buy the flex sensor stuff.

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