Taking to shop for MPG issues; what to check?

[JohnnyO]

It's very hilly where I live so on all the trucks I've owned I've never gotten the mpg that some people claim on the the internets.
My suggestion is use higher octane gas. The owner's manual specifically says to use 91 for best performance, when towing a trailer, or in extremely hot weather, which you may have in CA.
I ran several tanks of everything and tracked the mileage.
Got 18-19 with 87.
Got 20 with 89 or E15 88.
Got 20.5 with 93.
So mostly I run E15 88 for the lowest cost of operation since it's the cheapest and the mpg is okay and 89 if I can't get E15.
Curiously, in this truck unlike my previous Rangers and Sport Tracs, the highway mpg isn't much different than my normal mixed driving mpg. But it's still literally 50% better than my old Sport Trac.
I might have a monthly payment again but I'm also spending $100 less a month in gas.

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[jblc]

My suggestion is use higher octane gas

Thanks for the suggestion. But like i've mentioned 5 times in this thread , higher octane makes my mpg go DOWN. I don't understand it.

 

[jblc]

How many tanks has it trended down?

I get 300 miles per tank when highway driving, so perhaps 5 full tanks? ~1500 miles.

The accepted spec is 1-2% less mpg per 100 lbs.

where is that from? I'm guessing that doesn't apply to steady highway-only driving, but mixed driving.
Even if that were the case at highway driving, that's just 5-10% less for the topper weight, and I should still be getting >22-23 mpg, vs the 17-18 i'm getting.

17-18 is 35% lower, the equivalent of 1700-3500 lb -- way more than 300-400 lb.

 

[Wytchdctr]

Buy a security camera? Maybe someone close to you is stealing small amounts at a time from you

@LevittownFordParts.com has a nifty lock for our weird fuel filler thing. Seems easy enough to break if someone really wants in (or i lose the keys)... but also annoying enough to stop someone in a hurry.

 

[Rp930]

I get 300 miles per tank when highway driving, so perhaps 5 full tanks? ~1500 miles.


where is that from? I'm guessing that doesn't apply to steady highway-only driving, but mixed driving.
Even if that were the case at highway driving, that's just 5-10% less for the topper weight, and I should still be getting >22-23 mpg, vs the 17-18 i'm getting.

17-18 is 35% lower, the equivalent of 1700-3500 lb -- way more than 300-400 lb.

https://www.autoblog.com/2009/10/29/greenlings-how-does-weight-affect-a-vehicles-efficiency/

 

[jblc]

https://www.autoblog.com/2009/10/29/greenlings-how-does-weight-affect-a-vehicles-efficiency/

Thanks! Yeah, that link doesn't specify HW vs city, and anyway, the numbers I replied with aren't in line with that anyway
("17-18 is 35% lower, the equivalent of 1700-3500 lb -- way more than 300-400 lb.")

 

[jblc]

Buy a security camera? Maybe someone close to you is stealing small amounts at a time from you

@LevittownFordParts.com has a nifty lock for our weird fuel filler thing.

Thanks! I have both already. Guaranteed nobody stealing gas, but good thought

 

[9zero1790]

drove about 300 miles today in the 5g. an out and back kind of trip. going i went 70 most of the way with the cruise set. way home traffic was less and i was ready to get back and went 80 with cruise set.. 21.5 on way then on way back truck said 21.7... so was the faster speed more efficient or was it simply that more highway miles were now in the mix. ?

 

[jblc]

drove about 300 miles today in the 5g. an out and back kind of trip. going i went 70 most of the way with the cruise set. way home traffic was less and i was ready to get back and went 80 with cruise set.. 21.5 on way then on way back truck said 21.7... so was the faster speed more efficient or was it simply that more highway miles were now in the mix. ?

Road slope can change in each direction, as well as prevailing winds that assist or resist motion, temperature could be different that causes different tire pressure, etc.

 

[9zero1790]

Road slope can change in each direction, as well as prevailing winds that assist or resist motion, temperature could be different that causes different tire pressure, etc.

very true. mpg just has so many factors.

 

[JimG_AZ]

I'm (yet again) taking my '21 XLT to the dealership, this time for MPG issues. MPG has always been really bad on this vehicle even when new, about 19-20 mpg highway (hand-calculated) at 65 mph and no wind, and stock 2wd. Adding a topper and new tires didn't change mpg.

Without any alteration since i got 19-20, the mpg has been steadily dropping to 17-18 over the past year, but more quickly over the past 6 months.

Is there any specific component I should ask them to check, relating to fuel efficiency?

Details:
(a) full-synthetic oil changes every 3k miles (8k miles total), and
(b) nominally-adjusted tire pressure as seasons change, and
(c) auto start/stop active, and
(d) 87 octane from quality station (California),

This is with gentle driving, mostly highway. I got 27 mpg on my '97 ranger, also with topper, so generally know how to drive efficiently and keep my vehicles optimally set up.


I feel like I've been taking this lemon in every two months since the month I bought it...sigh.
Welcoming any suggestions on this issue!

I have a '21 FX4 and mine gets similar fuel economy. I commonly see 17-18 mpg. This is using Costco premium gas. My commute to work is @ 7 miles each way and a lot of lights. What I have found is that my Ranger does not like short trips with stop-and-go driving. For full disclosure, I do have a leveling kit and the Tremor All-terrain tires on my truck. I probably lost 1 mpg by going from the stock Hankooks to the General tires. Also, my speedometer/odometer is @ 3% off.

 

[jblc]

My commute to work is @ 7 miles each way and a lot of lights. What I have found is that my Ranger does not like short trips with stop-and-go driving.

Yep, that makes sense for stop-and-go, and I agree the ranger doesn't like that Unfortunately I see that mpg on the highway though when driving steady at 65 mph.

 

[JimG_AZ]

Yep, that makes sense for stop-and-go, and I agree the ranger doesn't like that Unfortunately I see that mpg on the highway though when driving steady at 65 mph.

I would see @ 21.5-22 mpg driving steady @ 70 mph.

 

[jblc]

I would see @ 21.5-22 mpg driving steady @ 70 mph.

Makes sense for leveled / bigger tires. That's still much higher than my 17-18 at the lower speed of 65...and my vehicle isn't leveled

 

[KJRR]

Read most of the thread but didn't memorize it so will try to cover new ground.
Have you added running boards, mud flaps, skid plates, removed the front air dam?
Any forescan mods?
Any intake mods, air filter change, spark plugs?
Add a brake controller, modified suspension, brake changes?
Not saying any of this is the cause and I know you've said you've had bad mpg since the start but look at this from the dealers perspective. They have no idea what mileage you were getting from the start and will look at any changes you've made as the cause. They aren't going to run extensive diagnostics free of charge.
If you have forescan, I'm pretty sure you can check the items airline tech mentioned.
Good luck

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