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I recommend running 2 tanks of 91 octane doing a long run at interstate speeds. It will get the computer woke back up and when you do the same long drive on 87 octane you will see at about 2 mpg gains. The fuel mapping gets stuck with your habitual driving an a couple tanks of 91 octane resets it. It is my experience. The higher octane by itself doesn't raise gas mileage it allows the motor to run mote comfortably especially in hot weather. This reset lets the puter do a better job for you when you start 87 octane again. Over time the puter will go back to the old hum drum way again. Remember the ecu/pcm learns your driving style and maps you. The greatest gas mileage will probably be ones where you drive for hours contiously at 50 mph or so.
Last edited by papa tiger; 07-12-2017 at 11:59 AM.
I recommend running 2 tanks of 91 octane doing a long run at interstate speeds. It will get the computer woke back up and when you do the same long drive on 87 octane you will see at about 2 mpg gains. The fuel mapping gets stuck with your habitual driving an a couple tanks of 91 octane resets it. It is my experience. The higher octane by itself doesn't raise gas mileage it allows the motor to run mote comfortably especially in hot weather. This reset lets the puter do a better job for you when you start 87 octane again. Over time the puter will go back to the old hum drum way again. Remember the ecu/pcm learns your driving style and maps you.
It's easy to forget this. Now, to make an excuse to run 2 tanks on the highway (that's about 640 miles out and back.. that's a good run to Memphis!
I drive +-800 miles a month so I don't mind filling up 91 every tank. If I drove 1200+ I would only use 87. Everyones situation is different, use what works for you. The engine is engineered to work on 87-93 (and flex) don't over think it and enjoy the drive.
I recommend running 2 tanks of 91 octane doing a long run at interstate speeds. It will get the computer woke back up and when you do the same long drive on 87 octane you will see at about 2 mpg gains. The fuel mapping gets stuck with your habitual driving an a couple tanks of 91 octane resets it. It is my experience. The higher octane by itself doesn't raise gas mileage it allows the motor to run mote comfortably especially in hot weather. This reset lets the puter do a better job for you when you start 87 octane again. Over time the puter will go back to the old hum drum way again. Remember the ecu/pcm learns your driving style and maps you. The greatest gas mileage will probably be ones where you drive for hours contiously at 50 mph or so.
Do you think this same thing happens on E85, as it does on 91/93?
These two statements seem to contradict themselves. "Our vehicles cannot tell 93 octane from 85 octane" and "slightly better performance" don't go together.
Just for the record, Ford posted their own numbers showing the Coyote engine at 360/380 on 87 octane and 375/390 on E85 pump fuel. It's a noticeable difference. Mine will hold 6th on a long hill I have to climb daily on E85, but will downshift to 5th if I'm running 87 octane.
Other guys have posted dyno results showing an increase in power and torque between 87 and 93 octane on these trucks also. These vehicles DO know the difference and there is a benefit, unlike the years gone by.
I thought I saw before the Eco boost went from 365/420 to 380/430 oddly the same spread as the 5.0 you reference. I would be interested on how its accomplished in the Eco. Timing only (assume that would be the case with the 5.0) or timing and boost? I pull 15 max boost...........wonder if it goes higher on 93
If you buy 93 octane after many thousands of miles of 87 octane and watch the puter it hunts all over the place for 100 miles. The system that controls the engine/transmission is torque demand. If you ask for torque the system responds with a multitude of sensor data to give the best answer, timing, fuel injection, transmission shifting, turbo boost psi/ camshaft timing thru the oil pressure controlled tiVct system, etc. Not just one thing is affected by octane. Reason for all the engine quieting stuff on it.
Well halfway through my second tank of 91 ethanol free, and I can safely say, no better than 87 octane as far as MPG is concerned. Power is not much different either. Really not worth the $23 increase in costs.
... the first reason is that the cost of premium has been going up (and apparently, so has the delta). The second reason is that it looks like the benefit to me with the driving that I'm doing (mix of fwy / city and loading) for premium is very close to not much. I think that Fuelly said that I'm getting 0.5mpg worse with 87 than with premium. The cost per mile driven is thus much better with 87, so that's what I'll stick with, even with the 100+ days we've been getting. At least until I need to tow something.
I drive +-800 miles a month so I don't mind filling up 91 every tank. If I drove 1200+ I would only use 87. Everyones situation is different, use what works for you. The engine is engineered to work on 87-93 (and flex) don't over think it and enjoy the drive.
Agreed... As I always say, stick to what's in the owner's manual. It says it can run on either regular or premium, but premium is recommended.
Not planning on running premium fuel in mine as well. We still have a few places here where the regular fuel is ethanol free.
07-12-2017, 11:55 AM
