Hello I have a 2005 GMC truck 1500 with the Flex Fuel vortec 5.3L v8. I filled my tank up today for the first time with E85 Fuel the truck runs great on it and the power is great too the smell is a little diffrent from the fewms out of the exaust pipe. its a hotter heat out of the tail pipe also. I was woundering if eny one else on this web page has ran E 85 fuel and how well there vehical runs on it. thanks for reading my inquire.

 

Keep track of your fuel milage. I'm intersted in the difference.

 

I wish I could FIND an E85 station.....

 

Everything I've read and heard indicates a drop in gas mileage with the E85. Like to hear how this works for you.

 

That's what I hear too, but also power loss. I am surprised someone hasn't come up with better alternatives; OH!! wait oil companies buy them out, kill the technology so they stay on top, and then gouge gas customers

 

Hi,
Yes it is correct that the milage will get worse with E85.
The reason is less energy content in the 85% ethanol in the E85 fuel.
You can expect a 5% power increase using E85, with out tuning, just the fuel change.
I the PCM there are actually different Tq curves depending on the ethanol content, as measured by the fuel composition sensor on trucks with the Z code engines.

The reason you feel "hotter exhaust" with E85 is propably because there is more water vapor formed when combusting ethanol than gasoline. Water will carry the heat further back from the engine, towards the exhaust tip.

I run E85 in my Tahoe, with my own tune. ( T engine)
I don´t have much to compare with, but my otherwise completly stock Tahoe is doing 0-60 mph in around 7/7,5 seconds. I don´t know how that compares......
Driving on the highway at around 55-60 mph i get round 17 mpg, doing 75 returns 14 mpg.

Br//

 

So is my 2004 capable of running off of straight E85? I think it's a "flex fuel" model, but I never paid much attention, so I don't know for sure.

 

Yes, if you have the flex fuel engine, you have larger fuel injectors to accomodate the higher ethanol volume needed over gasoline.

A dyno tune with E85 in the tank would help get optimum results I would think. The stock tuning should work fine, buit we all know how conservative the factory tunig is.

peace
Hog

 

If you have the L59 RPO for the engine you have a flex fuel 5.3L. They have 38LB HR injectors if I recall correctly.

 

I do not remember for sure but no FF in the 4.8 colby.