hi people new 2013 fx4 ecoboost owner here was was wondering if I ran higher than recommended octane in my truck does it make a difference in performance and mileage.thanks

 

I have a 2013 Lariat screw 4x4 ecoboost with 15K miles and higher octane fuel does make a slight increase in both performance and mileage. I tried 93 octane 3 times with 3 fillips each trial. For me it wasn't worth the extra cost. If I had been towing heavy loads it might be worth it

 

It's not worth the extra cost for power and mpg, but several tuners recommend a higher octane even with stock programming. Detonation can cause problems and there have been a few cases of engines throwing rods under hard acceleration due to detonation. I run mid-grade all the time for the slight octane bump, usually 91 vs 87, premium here is 92-93. I ran premium for 3 months and noticed a DECREASE in mileage. My truck seems to like mid-grade the best.

 

Please see attachment...from Owner's Manual.



biz

 

Interesting...in my manual (for 2016), it just says "We recommend regular unleaded gasoline with a pump (R+M)/2 octane rating of 87. Some fuel stations offer fuels posted as regular unleaded gasoline with an octane rating below 87, particularly in high altitude areas. We do not recommend fuels with an octane rating below 87.

For vehicles with EcoBoost engines, to provide improved performance, we recommend premium fuel for severe duty usage such as trailer tow"

So they removed the 91 octane reference for best performance and just suggested "premium fuel" when towing.

 

From my 2017 Expedition 3.5L manual

FUEL QUALITY
Choosing the Right Fuel
E161513
Your vehicle is designed to operate on
regular unleaded gasoline with a minimum
pump (R+M)/2 octane rating of 87.
Some fuel stations, particularly those in
high altitude areas, offer fuels posted as
regular unleaded gasoline with an octane
rating below 87. We do not recommend
these fuels.
For best overall vehicle and engine
performance, premium fuel with an octane
rating of 91 or higher is recommended. The
performance gained by using premium fuel
is most noticeable in hot weather as well
as other conditions, for example when
towing a trailer. See Towing (page 203).
Do not use any fuel other than those
recommended because they could lead to
engine damage that will not be covered by
the vehicle Warranty.
Note: Use of any fuel other than those
recommended can impair the emission
control system and cause a loss of vehicle
performance.
Do not use:
• Diesel fuel.
• Fuels containing kerosene or paraffin.
• Fuel containing more than 15% ethanol
or E85 fuel.
• Fuels containing methanol.
• Fuels containing metallic-based
additives, including manganese-based
compounds.
• Fuels containing the octane booster
additive, methylcyclopentadienyl
manganese tricarbonyl (MMT).
• Leaded fuel (using leaded fuel is
prohibited by law).
The use of fuels with metallic compounds
such as methylcyclopentadienyl
manganese tricarbonyl (commonly known
as MMT), which is a manganese-based
fuel additive, will impair engine
performance and affect the emission
control system.
Do not be concerned if the engine
sometimes knocks lightly. However, if the
engine knocks heavily while using fuel with
the recommended octane rating, contact
an authorized dealer to prevent any engine
damage.
FUEL FILLER FUNNEL
LOCATION
The fuel filler funnel is under the luggage
compartment floor covering.
RUNNING OUT OF FUEL
Running out of fuel can cause damage not
covered by the vehicle Warranty.
If your vehicle runs out of fuel:
• Add a minimum of 1.3 gal (5 L) of fuel
to restart the engine. If your vehicle is
out of fuel and on a steep slope, more
fuel may be required.
• You may need to switch the ignition
from off to on several times

jeff

 

I normally hang out in the FE or bumpside forums, but I do have an 2010 Flex with the 3.5 Ecoboost. What I know about modern electronically controlled engines is mostly theory (I have gotten dirty on an FE, but it is not really the same thing), but these engines can adjust the timing to compensate for knock or pre-combustion.

I was getting some strange behaviour out of my Ecoboost that I think was the knock sensor backing off the timing. This happened occasionally here in Calgary where I know what kind of fuel I'm buying, but when I took it to the states and was not buying the usual regular fuel I'm used to it happened all the time. It amounted to a really loud tick on partial throttle at lower speeds with a slight loss of power.

Changed to running premium and the problem went away. Higher octane fuel has no more energy per gallon, what makes it "premium" is a higher octane rating that means a higher flash point, or in simple terms greater resistance to igniting. This means you can run higher compression or tolerate less than ideal combustion chamber conditions without having to change the timing characteristics.

More timing advance often means greater power, but it is within some fairly narrow ranges. Old school engines needed to have it done mechanically and painstakingly. Modern engines it is handled by the PCM.

 

I have found slight gains of 15-20% better mileage purchasing fuel that is ethanol free. My toyota went from 33 to 35-36 in the same conditions.

 

With my Eco Boost 3.5 in a Lincoln MKS I notice that using either Shell or Co-op premium works good because it is 100% gas. No ethanol at all. Once every couple of months I will fill up with either Husky 104 or Petrol Can Ultra to get rid of any water in the tank. I notice a significant drop in mileage when I do. I am a fan of pure gasoline when it comes to these engines. On the other side if you want to tune them to run on E85 then they can also work very well but will suffer on MPG. There is lots of debate on fuel grade and I can't provide anything more than my personal feeling on the subject. I will continue to be happy with the way my car runs on Shell Gold...