drop in mpg - Diesel Forum - TheDieselStop.com
6.7L Power Stroke Engine and Drivetrain Discussion of the 6.7L Power Stroke diesel engine and drivetrain in the 2011-Up Super Duty trucks. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.7L Power Stroke engine.

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post #1 of 11 (permalink) Old 03-13-2012, 09:19 PM Thread Starter
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drop in mpg

I have a 2011 F-350 super duty, dually, which at the time had around 4,200 miles on it and I was getting 18mpg and climbing, however, after having a sensor changed and the computer flashed it has dropped to 12 and 13mpg. As of now the truck has 13,000 and still has the same problem. Is anyone else having any similar problems with the new ford upgrade?
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post #2 of 11 (permalink) Old 03-13-2012, 10:31 PM
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Same here. I'm going to be taking it to the dealer soon because the pile of crap transmission almost got me hit by a truck three days ago. I'll gripe about the mileage at the same time. I have doubts that there will be any real fix for either.

2011 F-350 Lariat Ultimate pkg. SRW, C.C., LWB, 4x4, 3.55 ELD
2010 Montana Mountaineer 345 DBQ (5th)
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post #3 of 11 (permalink) Old 03-14-2012, 03:12 AM
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My truck has been perfect with no real problems but I did see a big fuel mileage drop.

When my early job 1 truck was new I could easily cruz empty and at 70 mph with my 3:73's get 19 mpg's. When I had about 5000 miles on it was when Ford provided the original 400/800 power re-flash. After the re-flash the best I could get really trying hard was about 15.

But towing my 15K 5ver or driving in town stayed about the same, pretty good.

2011 Lariat Long Bed Crew Cab Dually 4X4
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post #4 of 11 (permalink) Old 03-14-2012, 11:27 AM
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My truck always gets better mileage when I just had the PCM/TCM flashed. Then it starts learning and it seems to learn bad habits. I don't horse my truck around, too old for that. Instead I use a light foot in town and a moderate foot getting on Interstates. Since the nearest Interstate to me is about 60 miles, I don't get on them often.

I would like to turn off this adaptive learning since it is only as smart as the guy that programmed it.


2011 Ford F-350 DRW Lariat Crew Cab 4x4 (8' Bed 3.73, Oxford White, Pale Adobe Accent, 6.7L, 10K GVWR, Lariat Ultimate Package, Tailgate Step, Universal Garage Door Opener, Upfitter switches, Navigation, Preferred Equipment Package)
Born: 6/15/2010 - Cost At Birth: $59,540 - Purchased: 7/17/2010
Mods: Added Engine Block Heater, LineX, Firestone Rear Airbags, Air Lift Wireless Compressor, LockPick, Added UpFitter Switches, Bed Lights, Torza Top Tri-Fold, Ultimate-EDP Alarm, Door Seal Mod., Rancho RS98510 Steering Stabilizer Kit, Bilstein 4600 HD Shocks.
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post #5 of 11 (permalink) Old 03-14-2012, 10:02 PM
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My truck has dropped since new. 5500mi on it now and has setteled in at 16.5mpg avg. when new it was around 18.7. I just might be having more fun driving it now though.

2012 F-350 6.7 Scorpion Lariat 4x4 CC DRW FX4 in Sterling Grey

The past:
'02 F-350 Lariat 4x4 CC SB 7.3/auto 245k. Time to step up! Sold
'99 F-350 XLT 4x4 CC DRW 7.3/6spd.156k. Tired of shift'n
'92 F-350 XLT Lariat 4x4 CC LB 460/auto. son rolled it!
'85 GMC Sierra 4x4 CC Dually 6.2/auto. too slow!
'78 F-250 XLT Lariat 4x4 SC LB. bought new, got married, had kids, needed 4 doors!
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post #6 of 11 (permalink) Old 03-14-2012, 10:34 PM
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I have the same problem. Driving empty hiway with a 4000 ft elevation change I got 19.5 mpg. Now i can hardly get 16 mpg with no elevation change. I got the 400 hp flash about a month after I got the truck. Towing I don't think I am doing much better than my 6.0 did.

2011 F-350 DRW 4X4 dark blue pearl/slate grey two tone Lariat ultimate. 3.73 limited slip 5th wheel prep/spray in bed liner. Named BRUTUS
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post #7 of 11 (permalink) Old 03-16-2012, 09:47 AM
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Just checked mine the other day after a fuel filter change at 13,700 miles, first during a regen I reset the meter and for about 10 miles at 65-70mph it averaged 12 mpg. After the regen I reset the meter again and at 70 it was 18.9for about 10 miles. I reset once more and the final 10 miles at 60mph it got 23.6.

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post #8 of 11 (permalink) Old 03-18-2012, 01:18 PM
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I averaged 9.1 MPG all miles run loaded and empty, for about 130,000 The mileage under the identical conditions is now about 7.5 MPG - fairly expensive at $4.10 average.
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post #9 of 11 (permalink) Old 03-18-2012, 01:32 PM
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What's wrong with my truck? F350 SRW. Diesel with 3.55 rear end. Synthetic 5w40 oil, new fuel filters, S&B cold air intake, correct psi in all tires, stock 20" tires, easy on go pedal--pitiful mileage. 12 around town, maybe 17 interstate. I tow a 2 horse aluminum horse trailer, and with two horses maybe 10 mpg. Towing a 16 foot empty flat trailer today, 12 mpg.

When new I got 22 mpg on interstate.

I'm considering the F150 Ecoboost. This is rediculous!

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2011-F350 SRW King Ranch, 20" wheels, all the bells and whistles...
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post #10 of 11 (permalink) Old 03-22-2012, 10:21 AM
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Your descriptions are one reason why, when my 2000 PSD reached 220k miles, I bought a 2002 7.3L 4x4 with 113k on the odometer rather than consider a new truck, even with financing. I'm getting 16.5-18.5 combined driving, with no load. I've been leery of diesels built since the 2008? emission reqs change. Hopefully the feds and manufacturers will sort this out before I need another truck, if ever, maybe 6-8 years out ..... I would still like to see a diesel truck [F150 style or maybe Tundra] designed to tow an 8-10k load [boat or maybe 3 horse alum trailer] and get 20 mpg combined mileage empty and 16 towing. One would think this would be a market sweet spot, but I fear the OEM's 'highest hp/torque' marketing, combined with the EPAs' demands, make this otherwise technically feasible vehicle a pipe-dream. sigh ......

2002 F350 Supercab Lariat 4x4 7.3L 6 spd. B&W gooseneck, Prodigy brake controller, PAC exhaust brake, WARN manual hubs, Ford AIS, Bilsteins, Michelin LTX, Line-X bedliner, 203F t-stat, Cat ELC coolant, by-pass coolant filter.
Wife's Ride: 2006 Mercedes Benz E320 CDI
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post #11 of 11 (permalink) Old 03-22-2012, 12:05 PM
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Mine works just as good as the day I got it, 10K miles on it now. I get 20 mpg on the highway, 17-18 hacking around secondary roads and 14 mpg towing my 16 ft extra high aluminum gooseneck with 2 draft horses at about a ton a piece. Keep in mind, mine is only a 250 with 3.31 rears.

I'm very pleased coming from a deleted 6.4L that wouldn't get 16 mpg on the highway and got 11 mpg pulling the trailer.

2011 F350 CCSB, 4x4, 6.7L, 3.31 E-Locker, MBRP 5" DPF Back, Innovative Torq 2

Past Toys:
2012 Ram 3500 CCSB, 4x4 6.7 Cummins, G56 6 spd

2011 F-250 CCSB, 4x4, 6.7L, 3.31 E-Locker

2009 F-250 CCSB, 4x4, 6.4L,Torqshift, Spartan

2009 Dodge 2500 QCSB, 4x4, 6.7L Cummins, 6 spd,

2007 Chevy 2500HD Classic, CCSB, 4x4, Duramax LBZ, Allison 1000, 4" MBRP Cat Back, Diablosport Predator, Edge Insight

2005 F-250 CCSB, 4x4, Torqshift, 4" Cat Back

2004 F-250 CCSB Fx4, 6spd, Bully Dog Intake, Banks 4" turbo back, Edge Juice

2002 F-250 SCSB, 6spd, AFE Intake, ATS Turbo Back Duals, B&D 60hp chip
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