Here you go 6.4 fans... Computer glitch is what I have heard - Diesel Forum

barryf350 · 05-09-2007, 10:12 PM

There is a glitch in the computer that keeps the truck in somewhat of a tow mold. One of our drivers who owns a 6.4 gets very poor mpg while towing. Not much better while "not" towing. It appears the computer puts itself in tow mode while towing but cant get back out of tow mode with no load. This glitch however can be random. Time will tell if this is accurate information.

bggroth · 05-09-2007, 10:28 PM

I took my truck on a 2000+ mile towing trip last weekend and was very very unimpressed with the milage. Pulling a traler that was about 5000 lbs and I averaged between 8 and 9 mpg. (all Interstate driving)

Brian

FLORIT · 05-10-2007, 12:55 AM

. . .5000 lbs and I averaged between 8 and 9 mpg. (all Interstate driving)

OUCH!
I just got back from a 300 mile trip with my 30' camper in tow with my '05 6.0 and got 10.5 mpg and thought that was bad!

The week before I transported ~50 yards of topsoil, 5 yards at a time in my dump trailer, across town, I'll guess 15-16,000 gvw, and averaged 9.5 mpg for the whole project.

Hope your mpg improves a lot! I would really like to see one of those 6.4's in my driveway, soon.

racerxxxr · 05-10-2007, 11:05 AM

I'm also getting very low millage out of mine. 8 towing 9.5 without is about it! Hope there is a reflash or something to coreect this soon. I did put larger tires on the truck but my 7.3 had the same tire combo and gears which got 10 mpg towing 15000 lbs. Which is why I bought this one!
[img]/ubbthreads/images/graemlins/frown.gif[/img]

lowerd96 · 05-10-2007, 01:47 PM

. . .5000 lbs and I averaged between 8 and 9 mpg. (all Interstate driving)

Yeah that is not too impressive, you should be getting maybe 13-14 with only 5K pounds...weird. [img]/ubbthreads/images/graemlins/shrug.gif[/img]

Rutcutter · 05-10-2007, 02:25 PM

Im headed over to texas this weekend to pick up a LX mustang and will have some #'s when I get back on the mpg's.

kenv · 05-10-2007, 02:44 PM

I also have a '30 Cougar Travel trailer and last summer I went to South Dakota and back with my '06 and averaged 10.5 mpg for the whole trip. If I kept it under 2000 RPM, I was getting 11.5 mpg. Dry the TT is listed at 7450, loaded for a two week trip, probably between 8000 and 9000 somewhere. I too would love to have a new one, BUT, the lower mileage stories are starting to get more frequent. This technology should be moving us forward - - not backward. I've heard some agruments say: "emissions this, EPA restrictions that", and "what do you expect for such a large truck".... but what I think the main point is, is that everyones identical 03's through 07 trucks were/are getting better mileage then their new '08's...and guess what, they are large trucks too. I'd be pretty disappointed to trade in my 2006 KR 4x4 Crew Shorty getting 15-16 unloaded to only getting 10-12 unloaded with a new identical truck.

Ken

jays2003 · 05-10-2007, 05:49 PM

Here is just my 2 cents. I have a 2008 250 crew 4x4. In town i get 13-14 unloaded Freeway is runnig at 22.5 -23.5. I also have a 28' 5th wheel dry weight is 10900 loaded is ( KIDS TOYS )13000-14000. I get 10.8-11.9 up hill down hill don't matter. My 03 6.0 would only get 9.5-10.5 towing, and only 11-12 in town and 17-19 on the freeway unloaded Go figure. Hands down I love my 08'

Escalarado · 05-10-2007, 06:55 PM

[ QUOTE ]
Here is just my 2 cents. I have a 2008 250 crew 4x4. In town i get 13-14 unloaded Freeway is runnig at 22.5 -23.5. I also have a 28' 5th wheel dry weight is 10900 loaded is ( KIDS TOYS )13000-14000. I get 10.8-11.9 up hill down hill don't matter. My 03 6.0 would only get 9.5-10.5 towing, and only 11-12 in town and 17-19 on the freeway unloaded Go figure. Hands down I love my 08'

[/ QUOTE ]

I am going to have to call BS on that statement all together. There is no way you are seeing that kind of mileage in that truck (check my sig I know). I just got back from a 300 mile freeway trip and I wanted to see what the best mileage I could get is. I set the cruise control at 62 mph and there were no hills or anything at all. It was as flat as you could get. I averaged 18.7 mpg the entire time. I couldn't get it to stay at 19 to save my life. And then for the around town driving I ease into it at every light and NEVER go about 2000 rpm EVER and am extremely lucky to get 12.5 and that is on a good week. And also take into account that these were hand caluculated miles. The lieometer is exactly what we call it.

jayhirsch · 05-10-2007, 08:25 PM

Haven't done an accurate hand check yet...but computer is hovering around 12.3 mixed city/highway( empty/not towing) . Which way does the " lieometer " seem to err? Also. I have heard mileage increases as mileage acumulates..was that your experience..I have just hit 800 miles?

Texrob1 · 05-10-2007, 08:30 PM

[ QUOTE ]
Haven't done an accurate hand check yet...but computer is hovering around 12.3 mixed city/highway( empty/not towing) . Which way does the " lieometer " seem to err? Also. I have heard mileage increases as mileage acumulates..was that your experience..I have just hit 800 miles?

[/ QUOTE ]The "lie o meter" will show better MPG than you are actually getting.Your truck should also get better MPG the more miles you get on it. [img]/ubbthreads/images/graemlins/biggrin.gif[/img]

krieghoff · 05-10-2007, 08:48 PM

You have to keep in mind a couple of things about the fuel mileage on these 08's. One, you are feeding more horses that you did in prior year models. My 08 is 350 hp vs 325 hp in my 07 & 05 & 04 6.0's. Just takes more fuel. My mileage is off as is everyones. Another reason is the emission level requirements this engine meets. In order to meet these EPA requirements, the engine utilizes passive and active regeneration cycles. Same as in big bore engines. Simply put, the ECM moniters your driving. If heat does not reach a certain level to burn off the soot through passive regeneration, the ECM commands the injectors to inject a predetermined amount of fuel into the exhaust cycle in order to burn off the soot in the DPF. This is why your engine RPM suddenly raises to about 11-1200 or so when you are sitting at a light with your mind off in space and it gets your attention. You have entered an active cycle. If you drive a lot of highway at 50+ MPH, you will do most of your regeneration in the passive cycle because of the heat generated. City driving is another thing altogether. As with refuse trucks that go house to house, they don't reach high enough heat levels to allow passive regeneration. For that reason we set them to an active mode at about 25 MPH.

The amount of fuel used in this cycle is being reviewed. It would not surprise me to see this adjusted in the future by way of a re-flash as it is controlled by the ECM. Fuel mileage on this engine (6.4) in reality should be better than what we got on the 6.0.

SmashedIxnay · 05-10-2007, 09:42 PM

I seen an 08 F250 King Ranch single wheel at Home Depot Monday and talked to the owner. He was very nice guy, even though I was all dirty from work, and told me to go take a look inside to see how it was. He was a very nice guy to allow me to do that cause I wanted to, but wasn't going to ask. I was impressed with the inside and overall I like the truck from the outside too. He did tell me he traded in his 05 F250 6.0 King Ranch single wheel in for it and is only getting 12mpg, unloaded with 3600 miles. I told him it still hasn't broken in and maybe it'll get better later, and he was hoping it would cause it cost him $51k he said! Overall he liked the truck, besides the mileage.

**KINGTUT** · 05-10-2007, 10:31 PM

[ QUOTE ]
Here is just my 2 cents. I have a 2008 250 crew 4x4. In town i get 13-14 unloaded Freeway is runnig at 22.5 -23.5. I also have a 28' 5th wheel dry weight is 10900 loaded is ( KIDS TOYS )13000-14000. I get 10.8-11.9 up hill down hill don't matter. My 03 6.0 would only get 9.5-10.5 towing, and only 11-12 in town and 17-19 on the freeway unloaded Go figure. Hands down I love my 08'

[/ QUOTE ]

There is NO WAY that the truck you have described will bring 22-23 mpg under the circumstances you have described. I hate to call someone out here, but I had to do it. No way......no way..... I am not even going to address the mileage you have stated dragging 14k around. [img]/ubbthreads/images/graemlins/shrug.gif[/img]

snowkartracer · 05-10-2007, 11:06 PM

We have 08 450 488 gears.We have 9500 miles now. Best milage we have seen is 11.5 and dont beleive we will ever see anything better. it doesent matter how slow or easy you drive the fuel milage just plain sucks.