Can we run 85 ethanol in the Bronco?

[Jdyount]

I like all of these super long answers, "With the proper tune,....".

The answer is No. No you shouldn't run E85.

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[22OBX]

A lot to unpack here. Ford has never used ethanol sensors like GM flex fuel vehicles do. They measure vapor pressure in the fuel tank and from that are able to infer the ethanol content of the fuel. A little more math than using a flex sensor directly, but it works.

Actually the sensor is the o2 right? It’s inferred flex fuel. The o2’s relay info back to ecu that can then interpreted in an ethanol content. Because the stoich values are so much different the o2 voltage signal will be different for each fuel. But either way I doubt the maps in the pcm has the table ranges nor fuel delivery capability to adapt fully.

 

[Laminar]

Actually the sensor is the o2 right? It’s inferred flex fuel.

You're right - I was going off an old ASME paper about inferring ethanol content via partial pressures. Ford uses a couple of triggers to detect a fillup, and then assumes rapid changes in AFR readings are due to ethanol content changes and puts those in a new flex table vs. the standard fuel trim tables.

https://static.oemdtc.com/GSB/G0000079.pdf

But either way I doubt the maps in the pcm has the table ranges nor fuel delivery capability to adapt fully.

In a factory system without Flex support enabled, the fuel trims will make up some difference, but will definitely throw a code before it's able to add the ~30% of fuel needed for full E85. Per my previous links, it can definitely account for lighter blends.

Because the trims are designed to accommodate slow injector or cylinder changes over time, they're not made to swallow an instant 10-30% change in fuel flow requirement. That's why even on factory Flex vehicles, Ford recommends adding as much of the new fuel as possible, and never less than half a tank.

 

[mpeugeot]

A couple things, as stated your mpg will be dramatically reduced and I find it difficult to believe without seeing actual dyno results it increases hp without tuning. Flex fuel compatible vehicles have ethanol content sensors in the fuel system which commands different fuel maps, timing maps and probably boost to take advantage of the cooler running high octane e85. Fuel alone there should be no benefit without tuning to take advantage of it. With tuning, yes you can make a lot more hp but fuel mileage will still be terrible.

Simply switching to E85 flex fuel won’t instantly increase your engine’s horsepower. Your engine needs:

To be compatible with E85 fuel
To be tuned to improve timing and power

Well, They didn't have a dyno with them in the Bronco and there was a Mustang on the Freeway.

Also, A/F ratios were fine, the stock computer has enough authority to make 30% E85 and 70% 93 run perfectly acceptable A/F ratios. I saw the lambda readings from the O2 sensors, it was a non-issue and spark timing did appear to advance over baseline.

I can only comment on what I witnessed.

 

[mpeugeot]

Actually the sensor is the o2 right? It’s inferred flex fuel. The o2’s relay info back to ecu that can then interpreted in an ethanol content. Because the stoich values are so much different the o2 voltage signal will be different for each fuel. But either way I doubt the maps in the pcm has the table ranges nor fuel delivery capability to adapt fully.

Actually, there is a dedicated sensor for some flexfuel vehicles that can give pretty precise information regarding the flexfuel mix. They have the advantage of improving open loop fueling without having to learn from the closed loop map.

It's important that the computer learn the long term/short term AF trims in closed loop before putting it into an open loop condition and hammering the accelerator pedal if you are planning to play around with this.

Edit: was unaware of the Ford FlexFuel strategy... that's pretty cool.

 

[mpeugeot]

I like all of these super long answers, "With the proper tune,....".

The answer is No. No you shouldn't run E85.

"Wow, so you can read the brochure."

Is it 6 or 7 quarts of oil for an oil change?

 

[mpeugeot]

Actually the sensor is the o2 right? It’s inferred flex fuel. The o2’s relay info back to ecu that can then interpreted in an ethanol content. Because the stoich values are so much different the o2 voltage signal will be different for each fuel. But either way I doubt the maps in the pcm has the table ranges nor fuel delivery capability to adapt fully.

No, AF ratios are different, but lambda stays the same. So you need a totally different AF ratio to achieve the appropriate lamba value.

Stoich is 1.0 lambda regardless of the fuel being used to the sensor (iirc).

 

[swami37]

Save the money. Gas is gas right?

 

[22OBX]

No, AF ratios are different, but lambda stays the same. So you need a totally different AF ratio to achieve the appropriate lamba value.

Stoich is 1.0 lambda regardless of the fuel being used to the sensor (iirc).

Agree lamda is 1.0. I meant a/f is so different for e85 and gas for 1.0 stoic. Technically it is not an o2 anymore but air to fuel sensor but it is the feedback for inferred fuel tables.

The strategy of inferred Flex Fuel relies on oxygen sensors placed in the vehicle’s exhaust system to return information back to the ECU that can then be interpreted into an ethanol content. While this may sound confusing at first, the method is actually quite simple. As exhaust gasses pas by the oxygen sensor(s), they will send back a voltage signal to the ECU. The voltage signal that is sent back will vary based on the air/fuel mixture in the engine at that time. Because E85 and gasoline have very different stoichiometric values (ideal ratio of air and fuel to support combustion), the voltage readings will be very different when each fuel is applied. The ECU can then use this information to determine what fuel is in the vehicle at that time and adjust the calibration accordingly.

Gas 14.7 - 1
E10 14.10 ish - 1
E85 10 - 1 (why you have to have more fuel)

And I stand corrected you probably would see a benefit up until the point the adaptive taps out, but at WOT I would be concerned going lean. Also I have seen warnings using e85 in a non e85 will damage emissions and void warranty.


From Ford document.

On 2004 MY and newer vehicles, the flex fuel sensor and module have been deleted and the ethanol percentage is now inferred. The closed loop fuel strategy uses a wide range O2 sensor (UEGO) to measure equivalence ratio of the exhaust gas. This feedback is used to deliver the correct amount of fuel to the correct stoichiometric ratio. The fuel equation includes short (SHRTFT) and long term (LONGFT) fuel trim, MAF (Mass Air Flow) as well as ethanol inference to calculate the desired fuel mass.

Ethanol detection uses the same logic as adaptive fuel, but it only makes adjustments when the system detects a significant fuel fill (>10% change in FLI level) and it believes that the fuel in the lines has been used. When the new fuel that was added to the tank is estimated to be at the tip of the injector, SHRTFT corrections needed to maintain stoichiometry are moved to FF_INF(inferred). Unlike adaptive fuel, the FF learning happens quickly. FF_INF affects the fuel pulse width in open and closed loop operation and applies during cranking.

During the learning process, all changes in the air/fuel ratio (AFR) are stored in memory. As updates are made, the ethanol percentage is updated and stored in keep alive memory (KAM). Learning continues until the inference stabilizes with stabilized engine operating conditions.

Resetting KAM will cause the PCM to initiate a relearn and infer the AFR immediately after going into closed loop operation.

 

[Jdyount]

"Wow, so you can read the brochure."

Is it 6 or 7 quarts of oil for an oil change?

I get it, you can tune the Bronco to run E85, but why? The Bronco is NOT a Mustang. Why anyone would want to void their warranty to pull a few extra HP and run MORE cheaper gas is beyond me. The Bronco has WAY more than enough power to do what it's designed to do, which off-roading if anyone forgot.

I mean it's really like you people are out here trying to rock crawl in a Mustang... Same thing.

Let's not forget the OP's original question, "Can we run E85 in the Bronco?". The answer is no, because without a professional tune you're going to be running too lean which CAN cause damage to your engine.

 

[mpeugeot]

I get it, you can tune the Bronco to run E85, but why? The Bronco is NOT a Mustang. Why anyone would want to void their warranty to pull a few extra HP and run MORE cheaper gas is beyond me. The Bronco has WAY more than enough power to do what it's designed to do, which off-roading if anyone forgot.

I mean it's really like you people are out here trying to rock crawl in a Mustang... Same thing.

Let's not forget the OP's original question, "Can we run E85 in the Bronco?". The answer is no, because without a professional tune you're going to be running too lean which CAN cause damage to your engine.

Well I don't know if I can run 100% E85 or not yet, I do know that I can run a blend without fear... Which means if someone accidentally puts a few gallons of E85 in the tank of a 2.7, it's not a big deal.

 

[Rcantu3135]

I personally ran E85 in my 2021 bronco for months and countless tanks. Maybe I should make a thread about my adventure.

1. The bronco ran better then ever. The engines timing or whatever was definitely improved to take advantage of the E85 (maybe not fully but still). I barely had to use the clutch to get moving. It really felt like I got a major HP and Torque boost vs 87.

2. The engine will throw a fuel code telling you its adaptive learning reached the maximum potential. This is actually a very useful error because it also disables engine start/stop automatically for you. I just continued to ignore it as it was running great.

3. You will see a SLIGHT decrease in MPG. I was getting around 17 before, with E85 I was consistently getting 16. Many people will start typing "ETHANOL HAS 30% LESS ENERGY THUS YOU WILL GET 30% LESS MPG" wrong. Ethanol due to its much higher octane (105-115) can handle much more compression, and if an engine can utilize the ethanol properly it will increase compression and squeeze much higher levels of efficiency out of it. It cannot do so with gas because of preignition.

Thats why if you tow with a flex fuel vehicle, you will notice that you will get the same mpg as gas or sometimes even better. Turbos love E85 and help increase the efficiency of it.

4. It cranks more for cold starts. E85 is rougher in the cold, let your car warm up a bit longer before driving off.

5. It keeps the engine cooler, longer.

6. Keeps the tail pipe spotless

7. Smells delicious.

When gas was $6 a gallon I could get E85 for $2.69. I will 100% use E85 again if gas goes high, but for now (prices dropped substantially) I switched to 93 since 87 feels lethargic to me and in my area (I moved) ethanol is the same price as gas or more.

Did u have to upgrade any fuel system parts?

 

[bytheway]

Agreed, I hope to data log something like this later.


No engine codes, no drama, stock maps, no engine mods - fuel trim was about +8% long term trim and +4% short term trim according to my friend. A/F Ratios were fine.

What did he use to read fuel trims and knock retard? I’d like to observe those figures but don’t have a handheld tuner or anything fancy. Was hoping there is a monitor I don’t know about.

 

[mpeugeot]

What did he use to read fuel trims and knock retard? I’d like to observe those figures but don’t have a handheld tuner or anything fancy. Was hoping there is a monitor I don’t know about.

I used my F-150's sct tuner for this purpose and to watch the lambda values. Fuel trims adjusted to compensate easily with 30% E85 + 70% 93 octane.

 

[lapazleo]

Putting it simply ethanol has less power by volume than gas even though it overall can make more power but it takes much larger volumes to do so. Any money you save on e85 goes out the window with lower fuel mileage. In other words an alcohol burning drag car requires roughly twice the volume of alcohol as it would racing gasoline hence a carb or injection system set up for alcohol.

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