Another Powerboost horrible mileage thread 12mpg

[F-150 Prius]

“My trips are anywhere from 2 miles to 6 miles, I do almost half of each trip in electric. I also usually remote start the truck and let it run for 5 minutes before I get into it.”

This is your issue. Crank it when you get in it & take a long 50 mile plus road trip with an engine that has actually warmed up, & then report your fuel mileage. This engine gives its best efficiency after it has warmed up by traveling a few miles. Otherwise, learn to live with what got. It is what it is.

I think that's probably the gist of it. PHEVs burn (iirc) seven times as much fuel and release that much more emissions when starting and a PHEV starts many times per trip. The "duty cycle" (if I have that term correct for this situation) is something the emissions regulators are going to revise for PHEVs so that the engine manufacturers meet mpg and emissions standards specifically designed for PHEVs.
If you drive a PHEV "correctly" the engine never burns fuel to keep itself warm and stop starts happen while the engine is operating temperature and the cats are hot. Otherwise the emissions go up and the mpg goes down.

As others have suggested in this rather impressively knowledgeable thread, I'd suggest driving down to empty, fill up to the first click, drive with no attempt to improve mpg, just a normal week or 400 to 700 miles and go back to the same pump with 10 miles in the tank, fill up and calc the actual gallons and miles. I've done this for 17777 miles in my PB and the mpg gauge is consistently within a few tenths of the actual hand-calc'd gallons and odometer miles. Efficiency has also improved over the first 10,000 miles. Maybe that was break-in, may be it was software updates and service updates (to the engine and trans) at the dealer as well.

p.s.
Recently, I changed the tires to a larger overall diameter, so I have a gps offset for speed of 1-2 mph, meaning my mpgs went "down" but not in reality – despite the larger, stickier and "treadier" all-terrains, the truck has lost maybe 1 mpg (except for sustained interstate driving at 80 mpg with a bed full of 1000lbs of gear … but I can't blame that on the heavy tread of the tires, just the heavy tread of my right foot.)

My real world gallons at the pump, miles on the GPS has gone from about 18-19 highway (highway and city) to about 17-18. I travel "about 500" and I put in about 28. The way I "economize" on fuel cost is to plan ahead with gasbuddy and pick the cheapest gas station in the next 50-100 miles … price can be a dollar difference in a city or 50 cents different on the interstate. 25-30 gallons by 50 cents is enough for me to justify a little planning and even when paying $5.00/gallon in California, 50 cents is a 10% discount net. There's nothing I can do while driving (at least nothing I'm willing to do) that can take me from 18 mpg to 20 mpg. I drive for minimum total trip time, not highest mpg.

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[DBL R]

Which tires? (size, load rating)
Factory fitment?
45 psi on factory half ton truck tires would be lower than most (usually 50+ to about 80 psi.)

275/60r20 Pirelli scorpion all terrain plus. It’s a p rated tire so doesn’t have the higher PSI of LT tires.

 

[PBXL]

I think there is a fascination with "electric only" miles and I understand that, but in my experience, there is not much correlation between that and your actual MPG. The normal Ecoboost is already rated at 24 MPG highway so what the hybrid allows is for city driving to more closely match the highway efficiency with regenerative braking, acceleration assistance, and turning off the gas engine when it is not needed. In fact, I get much worse "electric only" miles than others on this forum, but my whole tank MPG always ends up close to EPA ratings. My personal opinion is that you shouldn't drive in a way to focus solely on maximizing the "electric only" miles and that if you can't get the 24 MPG highway that is the same between Ecoboost and Powerboost motors, then there is something wrong somewhere. This is also based on my experience owning 3 Toyota hybrids. Toyota hybrids (non plug in) cannot go more than a quarter mile in electric mode, yet get incredible MPG. None of my Toyotas even tracked that "electric only" miles value.

 

[Stealthytt]

I think that's probably the gist of it. PHEVs burn (iirc) seven times as much fuel and release that much more emissions when starting and a PHEV starts many times per trip. The "duty cycle" (if I have that term correct for this situation) is something the emissions regulators are going to revise for PHEVs so that the engine manufacturers meet mpg and emissions standards specifically designed for PHEVs.
If you drive a PHEV "correctly" the engine never burns fuel to keep itself warm and stop starts happen while the engine is operating temperature and the cats are hot. Otherwise the emissions go up and the mpg goes down.

As others have suggested in this rather impressively knowledgeable thread, I'd suggest driving down to empty, fill up to the first click, drive with no attempt to improve mpg, just a normal week or 400 to 700 miles and go back to the same pump with 10 miles in the tank, fill up and calc the actual gallons and miles. I've done this for 17777 miles in my PB and the mpg gauge is consistently within a few tenths of the actual hand-calc'd gallons and odometer miles. Efficiency has also improved over the first 10,000 miles. Maybe that was break-in, may be it was software updates and service updates (to the engine and trans) at the dealer as well.

p.s.
Recently, I changed the tires to a larger overall diameter, so I have a gps offset for speed of 1-2 mph, meaning my mpgs went "down" but not in reality – despite the larger, stickier and "treadier" all-terrains, the truck has lost maybe 1 mpg (except for sustained interstate driving at 80 mpg with a bed full of 1000lbs of gear … but I can't blame that on the heavy tread of the tires, just the heavy tread of my right foot.)

My real world gallons at the pump, miles on the GPS has gone from about 18-19 highway (highway and city) to about 17-18. I travel "about 500" and I put in about 28. The way I "economize" on fuel cost is to plan ahead with gasbuddy and pick the cheapest gas station in the next 50-100 miles … price can be a dollar difference in a city or 50 cents different on the interstate. 25-30 gallons by 50 cents is enough for me to justify a little planning and even when paying $5.00/gallon in California, 50 cents is a 10% discount net. There's nothing I can do while driving (at least nothing I'm willing to do) that can take me from 18 mpg to 20 mpg. I drive for minimum total trip time, not highest mpg.

How accurate is DTE though? A full tank results in a DTE of 360ish. I in no way expect 24mpg on Hwy or City, I'd be happy to get a real world 18mpg. I have done a tank where I just drive and that has resulted in 15mpg with 200 miles being hwy miles. I do mainly city driving.

I have gotten no where near realistic numbers, that is why I tried to see what I could get if I maximized my electric driving, and was light on the throttle when using the engine.

 

[AgieF150]

Hey Dspyv, thanks for the response

I pumped at Chevron, at the same pump both times, I pump to the 1st click both times.

I agree the numbers would be off, but at the same time I highly doubt my method is gallons apart from eachother.

fill up, wait 20 sec fill again, then calculate both times.

 

[Stealthytt]

fill up, wait 20 sec fill again, then calculate both times.

I will try that on this next fill up, thank you

 

[F-150 Prius]

I will try that on this next fill up, thank you

Nope. : )

fill up, wait 20 sec fill again, then calculate both times.

Do not "top" up. Modern vehicles have a sealed fuel system which can be damaged or malfunction if overfilled. From the owner's manual:

 

[AgieF150]

Nope. : )


Do not "top" up. Modern vehicles have a sealed fuel system which can be damaged or malfunction if overfilled. From the owner's manual:

you are not overfilling, TFL always use this technique for hand calculation of mileage.

 

[F-150 Prius]

you are not overfilling, TFL always use this technique for hand calculation of mileage.

They're wrong to use their 30 second "click" method. If you can't take it from the owner's manual, I don't expect you to take advice from me.

 

[Stealthytt]

After a 216 mile hwy trip, 20.1mpg, 75-85mph, with a couple passes around cars. (20 of that was city driving when I arrived at my location). Vehicle calculated MPG was 20.4

This is fine with me, I am happy with that number as the EPA rating was not rated at 80mph.

I have currently topped off and reset, going to just drive it without shooting for efficiency.

 

[daemonic3]

While I do love getting a lot of electric miles just for the personal satisfaction of it, it has to be noted that those miles aren't really "free", you paid for them with burning extra gas that an ecoboost otherwise wouldn't have. The only way to generate the electricity for the battery is by adding resistance to something spinning, either through the regenerative braking or through the big ass generator on the serpentine belt of the powerboost engine. If you are coasting at 1.3k rpm in an ecoboost that will have less resistance than 1.3k rpm in a powerboost when it is doing battery charging. The engine has to work harder (use more gas).

How much harder does it have to work? Well I'm not sure but it is glaringly obvious how much resistance the generator can add when using the regen braking in the region before applying friction braking. And obviously I do not work on the design of these hybrid engines but they must have an algorithm to gradually release that resistance once the battery is full so the drive belt resistance is about the same as an ecoboost (or else the hybrid would be a horrible design!).

Anyway, my point is that even though electric miles are fun and cool, they aren't free because you prepaid for the battery using gas. That's why you can have some trips with nearly identical MPG but very different % electric miles.

For fun here's an image of the ecoboost drive belts vs the powerboost. They are very different. Ecoboost has to have alternator, pump, A/C, generator, but the powerboost only has the huge generator and I think that 2nd belt is for the coolant pump. That generator has gotta add massive resistance (when charging) compared to the alternator on the ecoboost.

 

[ATLalien]

I know it's another one, sorry in advanced.


I've had my Powerboost (all stock) for about 3000 miles now, this last tank I set out to see what I could get in eco mode only, with city driving. All driving was my normal day to day trips, remote start was used for at least 3 mornings per week for the 30 days on this tank, roughly 5 mins for those days. I did not floor it or drive aggressively also.

I did 146 total miles before filling up (going out of town)

Out of the 147 total miles 69 of them were electric only miles. 78 miles with the ICE. This last fill up I put in 11.43 gallons of fuel for a hand calculated 12.8mpg. The truck calculated 17.6mpg was way off, with the amount of electric only miles I figured I would have had some good results, this is just disappointing. When I think that I have only gone 78 miles on a gas engine using 11 gallons of fuel, it just disappoints me even more lol.

Anyone else on the same boat? I have not taken it in, and not sure if they can do anything if I did.

Without towing, or running at wide open throttle for extended periods while climbing mountains, it's really hard to imagine any other circumstances that would produce this kind of mileage. Even the standard 3.5 EB or the 5.0 could easily do better.

Unfortunately for the OP, I think it's pretty simple; either your hand calculation is off, or there's a problem with the truck.

 

[MaximusW]

Hey Stealthy,
11 to 12 mpg sounds like towing gas mileage, were you towing something? If not, i would recommend checking your tire pressure, quality of gas(try changing gas station) or just get the vehicle checked.
To give you some idea, i have been regularly tracking all my fill ups (hand calculating gas mileage for about 6300mi so far) and my numbers are 17.7, 18.2, 20.1 , 19.2, 21.8, 20.7, 21.7, 20.4, 20.6. My driving is about 50% city and 50% highway. The trip computer is pretty close to the hand calculated numbers, so far. All stock powerboost 4x4 fx4, 18s. Regular pump gas.
I also drive about 75 on the hwy, so i understand why my gas mileage is lower than advertised.

11 to 12mpg seems super low for a stock powerboost.

Ditto (averaging between 19-20MPG)

 

[firesprinkguy]

Hey Stealthy,
11 to 12 mpg sounds like towing gas mileage, were you towing something? If not, i would recommend checking your tire pressure, quality of gas(try changing gas station) or just get the vehicle checked.
To give you some idea, i have been regularly tracking all my fill ups (hand calculating gas mileage for about 6300mi so far) and my numbers are 17.7, 18.2, 20.1 , 19.2, 21.8, 20.7, 21.7, 20.4, 20.6. My driving is about 50% city and 50% highway. The trip computer is pretty close to the hand calculated numbers, so far. All stock powerboost 4x4 fx4, 18s. Regular pump gas.
I also drive about 75 on the hwy, so i understand why my gas mileage is lower than advertised.

11 to 12mpg seems super low for a stock powerboost.

so interesting facts for me on this. One day I ran my truck dry and was able limp the truck 200 feet to a station (don’t ask, I have not done that since I was a teen), I filled 32 gallons, which I anticipated, a couple weeks later we were at our cabin and I forgot to fill in the way there and on our way out I did cut it a bit close, but had 20-30 miles left in the tank and oddly enough I filled 35 gallons, which was not possible. The pumps were surely calibrated differently. Also, I’ve noticed what others have pointed out, fuel quality is a thing, my check engine light has been on often, I have a lengthy list of notices on the app and they usually appear after it has been remote started. If I choose high quality, high octane, the frequency of check engine light notices diminishes a lot, to almost if not zero. Mileage also increases and is considerably higher than yours, 15-17 for the same type of driving and I like putting my foot in it.

 

[Guntoter535]

You have to look at it like this : You drive uphill and you burn 11 gallons all engine and get 12 mpg. You then drive down hill on all electric and the cars mpg goes up to 17 mpg. The 11 gallons is still gone. You just generated a higher mpg (40 mpg plus)on the way down then you used when you went up(12 mpg) so the average gets a little messed up.

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