True mpg #'s - Diesel Forum

POOMAN · 10-13-2009, 05:49 PM

Everyone tired of the bs #'s thrown around about mpg's? Here is what I got this past week coming from huntsville,tn to chicago,il via I65 route.
Overall average 8 mpg 1150 miles.
worst was 6.72 from indy to chicago with head wind, running 75 -80 towing my 10,000 lb enclosed trailer.

My old 6.0 averaged 12 with same trailer same speed with 9 being the worst on I65 bucking a heavy wind,
It's hard to believe the dpf alone can cause that much fuel loss.

johnny87 · 10-13-2009, 06:27 PM

From 12 to 8 mpg. That is significant! Ya know the old Ford/International decided to go ugly early with the EPA crap, hence the issues with the 03/04 6.0L. The 6.4 is more robust and sacrifices fuel economy for emission targets. I had a friend at work who gutted all of the EPA stuff from his 6.7L Cummins and he was pretty happy with the results. It did take a little doing though. Sounds like the 6.7 PSD will restore the loss of fuel economy....can't wait to see for what price.

How do you do hwy/city/rural with out the trailer?

JohnD333 · 10-13-2009, 06:34 PM

Yup, worse mileage than earlier models but "doesn't that truck look sweet" says the dealer. Oh, and the smooth ride with tight turning radius.

The 6.4's sit a bit taller, and weighs quite a bit more too even in the same 250/350/450 class, but more importantly did your 6.0 have the same finalk drive axle ratio? Same number/type/diameter of tires?

At those speeds there are some big differences depending upon the gear ratio you ended up with. I have heard 1.5 to 2.0 less mpg's is to be expected because regen was not needed for the 6.0 to meet the emission mandate in effect when the 6.0 was in production.

Oh, less we forget, the ULSD fuel was $1.00 when auto makers told regulators it would cost 25% more to refin out the sulfur; that would have added 25 cents to a gallon. at $4 last year that refining process was adding a full dollar to the price at the pump.

It's not close to being over. Get over it.

If all you have trouble with is consuming fuel, not having it in your oil or the rig in the shop, consider life as good as it gets with a new rig.

JohnD333 · 10-13-2009, 06:42 PM

Johnny 87,

Having been an early adopter of a Job 1 (April 2007) Job 1 450 that has been in the shop for 79 days in the last 12 months / 10 k miles (27k miles total), I wouldn't go near the sure to be hiped 6.7 until it has been on the road for a year or more.

PS, have you looked at your trade value- its 1/2 of new for a reason...

PPS, Lemon Laws in Florida do not apply to anything larger than a 250 and Ford Corporate says TOUGH - sue me.

SFC1984 · 10-13-2009, 07:31 PM

From Dallas to Bossier, La last night, driving at 65 or a little less, I got a best of 15.6 mpg before Regen kicked in and knocked it down to 15.4.

That was with a few hundred pounds in the bed and the back seat full. '09 F350 4x4 CC LWB SRW 3.73 gears, 20" wheels and a 5sp tranny. I was able to use cruise control the entire trip, using just the Set +/- buttons on the steering wheel to control the throttle. I'm sure I could have gotten better results if the drive had lasted longer, but I slept on the drive back while my dad took driving duty and he doesn't drive like me. He maintained a constant 15.4 the entire way back though.

I'll also mention that we use Motorcraft diesel additive with every fill up.

Martin #6 · 10-13-2009, 08:07 PM

I made a trip from Ca to Canada last month. Not towing, but the bed was loaded with bicycles, gear, the usual vacation stuff and an A.R.E. shell. My average mileage for the 2000 miles was 17.6 mph running 65-70 mph. All stock except for the DPF-R kit, so some things were removed, meaning no regens. Towing is a different story. Same set up. My TT weights #7500 at the most. I usually tow between 60-68 mph. If I'm in the hills my mileage sucks, 6-8 mpg and I struggle to pull the hills at 55-60. Towing on flat ground with a headwind results in the same poor mileage. If it's flat and no headwind I can get around 10 mpg. Quite a bit different than what I was used to with my early 99 PSD when I had a ton of power to spare and my mileage towing was 10-12 in the hills and headwinds.

2008 F-250 4x4 w/18" wheels and 3.55's.

mriguy · 10-13-2009, 08:17 PM

do you think four wheel drive makes a difference? i had shift on the fly on my gas burner 5.4l f150. and would get 12 around town and lucky to get 14 on the hwy. my dad has two wheel drive and gets 19 hwy. so with this truck i do not have shift on the fly just a stick on the floor will that make a difference? this is my first diesel and am trying to learn as much as possible.

POOMAN · 10-13-2009, 08:50 PM

I forgot to add truck details:2009 350 4x4 ccsb 3.73 auto trans 20" rims 4800 miles.
Not towing i get 12-13 hwy running 55-75 mph. Don't drive city enough to get mpg report. 6.4 does not tow my trailer any better than the 6.0 did. I did notice pulling hills the motor would de power if egt were getting to high. some hills I could climb without slowing down and on others seemed very doggy like I was down on power. I'm not complaining as I new before i bought about the crappy mpg's, I just wanted to post some real #'s.

SFC1984 · 10-13-2009, 08:59 PM

I've never noticed this in other diesels we've had while using cruise control, but once you set your speed, the RPMs will hold steady and boost will kick in to adjust the speed if you're going up a grade, or back off if you're coasting down a grade.

Quote:

Originally Posted by mriguy

do you think four wheel drive makes a difference? i had shift on the fly on my gas burner 5.4l f150. and would get 12 around town and lucky to get 14 on the hwy. my dad has two wheel drive and gets 19 hwy. so with this truck i do not have shift on the fly just a stick on the floor will that make a difference? this is my first diesel and am trying to learn as much as possible.

You have to factor in additional weight of parts, such as the transfer case, etc. That's why 2wds are rated to pull slightly more than 4wds. Also, trucks can be shift-on-the-fly whether they have a manual transfer case stick or an electric knob on the dash. My old gas Dodge was 4wd and was shift-on-the-fly with a stick on the floor for the transfer case.

Greyman · 10-14-2009, 07:40 AM

Commuting about 160 a day, for 3 weeks, hand calc'd 15.39 including a regen about every 420 or so.

BeatMarti · 10-14-2009, 04:12 PM

Quote:

Originally Posted by POOMAN

I forgot to add truck details:2009 350 4x4 ccsb 3.73 auto trans 20" rims 4800 miles.
Not towing i get 12-13 hwy running 55-75 mph. Don't drive city enough to get mpg report. 6.4 does not tow my trailer any better than the 6.0 did. I did notice pulling hills the motor would de power if egt were getting to high. some hills I could climb without slowing down and on others seemed very doggy like I was down on power. I'm not complaining as I new before i bought about the crappy mpg's, I just wanted to post some real #'s.

Sounds to me that there is something else wrong. You removed the DPF and should get much more power and much lower back pressure and EGT temps than stock. However, you seem to experience de-fueling when climbing hills. This is usually triggered by excessive EGTs. There is an intricate connection between MAF, MAP and exhaust pressure sensors. Each could easily have a problem. The MAF gets messed up by oily deposits from the crank-case ventilation system, the MAP sensor can get clogged by gunky stuff from the EGR and the exhaust pressure sensor can get clogged as well. Unless any of these sensors radically fail, there will be no codes, but sluggish power and possibly excessive EGTs.

I had this issue and found the MAF to be the culprit. I replaced it because the IAT1 value was about 30 degrees higher than ambient after an overnight soak. I found out that both the mass air flow and intake air temp sensors are combined in the same unit. In reality, I suspect the MAF was probably more of a problem than the wrong IAT, but who knows... my engine works like a charm again!

Cope · 10-15-2009, 10:56 AM

I regularly see 15.5 -15.7 on interstate only driving at a strict 70mph unloaded, regens included. Mixed driving (town & highway) I see anywhere from 12.5 to 14.4. All figures are hand calculated and I always fill the fuel up to where I can see it in the filler neck so that I can try to be consistent in my mpg calculations.

My older powerstroke definitely did much better in the mpg department, but I still enjoy how much nicer this truck is overall.

POOMAN · 10-15-2009, 03:28 PM

Quote:

Originally Posted by BeatMarti

Sounds to me that there is something else wrong. You removed the DPF and should get much more power and much lower back pressure and EGT temps than stock. However, you seem to experience de-fueling when climbing hills. This is usually triggered by excessive EGTs. There is an intricate connection between MAF, MAP and exhaust pressure sensors. Each could easily have a problem. The MAF gets messed up by oily deposits from the crank-case ventilation system, the MAP sensor can get clogged by gunky stuff from the EGR and the exhaust pressure sensor can get clogged as well. Unless any of these sensors radically fail, there will be no codes, but sluggish power and possibly excessive EGTs.

I had this issue and found the MAF to be the culprit. I replaced it because the IAT1 value was about 30 degrees higher than ambient after an overnight soak. I found out that both the mass air flow and intake air temp sensors are combined in the same unit. In reality, I suspect the MAF was probably more of a problem than the wrong IAT, but who knows... my engine works like a charm again!

I didn't remove the DPF, this truck is bone stock with 4800 miles on it.

jasonlisan · 10-16-2009, 10:11 PM

Previous Truck: 2006 F-250 6.0 3.73 rear 4x4 CC I averaged 16-17mpg mixed city/hwy highest was 21mpg (with a nice tail wind

) & I averaged 10-12mpg towing the toyhauler

Current Truck: 2008 F-450 Job #3, 4:30 rear 4x4 CC I average 10.5-12mpg mixed city/hwy highest was 13.1mpg & I average 6-8 towing the same trailer. Now keep mind that the truck is heavier, has a lower rear end I average 70mph while towing. Now if I slowed down a big I might & it's a big might, I'll get 8.5-9mpg. I love this truck like no other but I hate the DPF, as someone else put it on another forum, there might be a terrible accident where it gets ripped off.

BarrySmith · 10-17-2009, 12:53 PM

I just returned from a 1000 mile trip from Tenn. to Indiana I had the cruise set on 70mph the whole trip. I ran about 250miles while there and overall hand cal. 15.7 mpg round trip. Which is pretty sad. I don't know how much the regens hurt mileage? How much fuel is shot into the DPF? 1gal, 2gal? My old Dodge would get 15mpg everyday city driving and 19mpg on the hwy. This truck gets 10.5 to 11.5 hand calc in town. I love the truck enough the mileage isn't so bad.