flex fuel/e85

[johnnyrauder]

does anyone the pros and cons of this fuel. om looking to buy a 2011 cop car. says its got flex fuel. ty.

[Noizy Child]

In the cop car, almost nothing.
In some places it is cheaper but it burns faster.
You rarely get the benefit of extra power unless you're tuned for it.

[johnnyrauder]

they say you can use eather one,reg or flex

[larryo340]

You can use either but with flex fuel your fuel economy will go down the tubes, I wouldn't be surprised if it got half of what you normally get. From what I know of you need to run 2 to 3 full tanks of flex fuel through the system before the computer will start to compensate, but you will still not get near the same fuel economy as with regular fuel. Don't waste your money on flex fuel IMHO

[johnnyrauder]

can you mix them, or is it one of the other?

[stevengerard]

I use flex fuel in my suburban. Rule of thumb is it gets about 30% less fuel economy. I see 25% - 35% less. Yes you can mix it I do it all the time. The computer adjusts just fine. Issue I have is even though I live in corn country often E85 is only 10% cheaper. If it's 20-30% cheaper I'll buy it. My way of "chipping in"


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[johnnyrauder]

ill prob. put super in, it gets the most mpg.

[Noizy Child]

I can assure you will get no better mileage running super in an 2011 cop car. Fill it with 87 and keep it moving.

[Mr. Man]

If the car is designed to use 87 octane then using 93 is just throwing your money away. E-85 comes into its own when a sheik in the Middle East farts, Wall Street panics and drives the price of oil through the roof. Since E-85 is derived from corn and America is corn abundant the price of E-85 can be cheaper. It will give you less miles per tank the regular gas. Yes you can mix the fuels in the tank.

[johnnyrauder]

well said guys, looks like om going to pull the trigger on the 2011 95k mi $5500.. pics when i get it..im test driveing it tomrrow

[fastblackmerc]

ill prob. put super in, it gets the most mpg.

False - a common misconception. The only thing that will happen if you run super in vehicle designed / tuned for regular is your wallet will be lighter.

[EMAS]

A couple of important notes about later Flex Fuel Fords. They and GM vehicles use what is called a virtual fuel composition sensor. In the early days they used a actual sensor that read the capacitance of the fuel to determine the fuel make up. What this means to an owner of a later Ford or GM FFV is that you should never just put a couple of buck worth of fuel in it. The GM TSB that addresses drivability concerns on their FFVs says that the customer should be advised to never put less than 5 gal in at a time.

The virtual FCS operates by sensing a refueling event. When the vehicle senses that it has more fuel when the key is turned on that what it had when it was turned off it goes into fuel learning mode. What that means is that instead of the O2 sensors driving the short term fuel trim which drives the long term fuel trim they drive the sort term fuel trim which drives the stored fuel composition. Because it takes a little while to properly learn the current fuel means that you should not shut the vehicle off until you've driven a mile or two. Don't fill up at the pump, pull up to the store and go in and buy something. Once it learns the fuel composition it will change the timing curve to optimize operation based on the fuel. Note that does not mean that since it has an adaptive timing curve that it will adjust for higher octane gasoline as the timing curve is based on fuel composition not octane.

There is a nice boost in low end torque with E85 as well as top end power. When we got our first FFV a 2000 Taurus there wasn't an E85 pump near me. I then took it on a trip that went by an E85 pump so I gave it a try and then topped it off again on the way home. The day after I got home the wife took it for a drive and she then asked what I did to her car. I thought that there was a dent or something like that. What she finally said was you mean you didn't tune it up or modify it in some way because it has more power now.

As others have mentioned there is a loss of fuel economy however there is a trick to get the benefit of increased power and lower cost w/o sacrificing fuel economy. The one wacky trick...? Running a blend that puts your fuel composition at around E40~E50 or filling up at a blender pump with that option. You get the benefit of the increased octane to compensate for the lower energy content of the ethanol and the fact that you can stuff more fuel in the engine when you want more power because the ethanol needs less air than gasoline.

I've seen a carefully controlled test done years ago with a number of different cars on different blends. The fuel economy curve went down from E0 to somewhere around E30 and then headed back up with somewhere between E40 and E50 matching the fuel economy of E10 or in some cases E10. It then takes a steep drop down particularly between the winter blend of E70 and the summer blend of E85.

I tried a slightly less scientific test of my own and on our Taurus ~E45 matched the MPG of E10. I wish E85 was available around here because I recently picked up a 09 E150 with the FFV 4.6 which is pretty much the same as used in the 09-11 CVPI.