Flex Fuel vs Non Flex

[donut slayer]

Is there any advantage for either? I'm looking at 2 Z71's, ones flex, ones not. I assume just different fuel mapping on computer and components in fuel system?

 

[CEN2MENTAL95]

FLEX FUEL can take pure E85 gas without modification (which I assume would involve fuel mapping and the rubber fuel lines being different)

 

[robdeniro0]

I have the yukon with flex fuel option and in my opinion the truck doesn't feel as strong with the E85 in it, plus it seems to burn faster. For those reasons I just put a 91 or higher octane in. On the other hand it is a nice option in the event we have a gas shortage.

 

[camperhead]

I have the yukon with flex fuel option and in my opinion the truck doesn't feel as strong with the E85 in it, plus it seems to burn faster. For those reasons I just put a 91 or higher octane in. On the other hand it is a nice option in the event we have a gas shortage.

Question for you? Do you have to do anything other than put e85 in it? i assume that the fuel sensor under drviers seat mounted to frame detects the different fuel and signals the ECU to make mapping changes... Guess its best to run the truck down on gas before switching to E85???

 

[tx tahoe z71]

Get the flex fuel. Bigger fuel pump and bigger fuel injectors. And you have the capability for running E85 if you ever want to supercharge or turbo charge it.

You won't gain any power by running E85 in it unless it is tuned for it. Mine is tuned for E85, so I get a 40-50rwhp bump from the added octane (about 105 octane, I'm also supercharged).

Depending on year, there is a special sensor that detects the mixture, so you can run 50/50 87 and E85 and the computer will adjust. Newer models, the O2 sensors pick up the mixture and there is no special sensor.

Fuel lines, fittings and everything else are the same because of manufacturing costs and difficulties of making separate ones for FF and non (from what I have read).

 

[Travieso]

Get the flex fuel. Bigger fuel pump and bigger fuel injectors. And you have the capability for running E85 if you ever want to supercharge or turbo charge it.

You won't gain any power by running E85 in it unless it is tuned for it. Mine is tuned for E85, so I get a 40-50rwhp bump from the added octane (about 105 octane, I'm also supercharged).

Depending on year, there is a special sensor that detects the mixture, so you can run 50/50 87 and E85 and the computer will adjust. Newer models, the O2 sensors pick up the mixture and there is no special sensor.

Fuel lines, fittings and everything else are the same because of manufacturing costs and difficulties of making separate ones for FF and non (from what I have read).

^+1 Correct what this man says, I have Flex Fuel also and im also Supercharged And Cammed, and Still running strong on the OEM Fuel pump making about 430-450 RWHP, goes to show you how strong these pumps are, i did have to change my Injectors to a bigger size

 

[felixgun]

E85 sucks.. you aren't missing anything if you DO get the flex fuel one aside from having a yellow gas cap. The fuel mileage on e85 is terrible and definitely not worth the "cost savings" which is totally counter productive since it gets WORSE fuel economy.

 

[mattvand]

I've got a flex '03Z, it's nice here in iowa because of how cheap E85 is due to subsidies. MPG w/E85 is about 11.5 city/town mix and mpg w/89 is 14ish. Turns out to be about 3 cents/mile cheaper to run E85 for me.

 

[donut slayer]

Thanks for the response guys. I think I'm gonna get a flex fuel one. My 04 Yukon is, so why not my newer one. We dont have E85 where I'm at in Florida, but I did see it everywhere in Colorado a few years back. I'm really looking at 2 vehicles now, both are 04's flex fuels. One is a 4x4 yukon and other a z71 hoe. The hoe is black and the kon is birch. Decisions, decisions.....

 

[sumo]

E85 sucks.. you aren't missing anything if you DO get the flex fuel one aside from having a yellow gas cap. The fuel mileage on e85 is terrible and definitely not worth the "cost savings" which is totally counter productive since it gets WORSE fuel economy.

full tank of E85 90% Highway Driving, I was only able to get 285 miles. Another 7 bucks of regular gas would got me another 100 miles.