5.4 Economy Troubles...

**Wolfpack Speed** · 01-19-2009, 09:50 PM

Anybody have a 5.4L powered ford truck? If so what issues if any have you had and what kind of city/highway mileage are you consistently seeing?

I have an 08 F250 just getting ready to turn 36K miles. For the first 25K miles or so I consistently got 11-12 city and 15-16 highway. Since then my mileage has dropped considerably, 8-9 city and 11-12 highway. I take care of my vehicles so it isn't a maintenance issue and the truck isn't throwing any codes. I pulled all the exhaust sensors and all is well there, ford ran diagnostics and we even flashed the computer. Without any codes and nothing showing up in the test results, I have no clue and neither does ford. Just looking for some feedback from any of the other 5.4 truck guys out there. I am in the market for a crew cab and want to go back to a diesel so I am half tempted to just trade the thing in but I would really like to wait a little longer as well as find out what the hell is going on with this thing!!!

Thanks!

Mike

**jaa55** · 01-19-2009, 10:07 PM

when we had our mark LT it would only do 15mpg on a good day and im not sure how much lighter it is than an f-250

**casper gt** · 01-19-2009, 10:12 PM

diesel? better wait for ford to get it together. the new 6.4's are worse than the 6.0's believe it or not. if you can live with an f150 though go for it my white one (r.i.p.) towed the car to columbus last year on like 40.00 worth of gas, one way of course ( 2008, 5.4, 3.55's)

**HidalgoGT** · 01-19-2009, 10:13 PM

Originally Posted by casper gt

diesel? better wait for ford to get it together. the new 6.4's are worse than the 6.0's believe it or not.

Yup, they have numerous problems. Rad's blowing apart. Egr's Complete failures. I think I even heard they offer 10 or 15k to do a motor swap if yours blows to do it by yourself lol. I'd go Cummins if Ya went the diesel route.

**HidalgoGT** · 01-19-2009, 10:11 PM

My brother has a 2000 superduty ext. cab 6ft bed with cap on it took it to michigan got like 10-13 on the highway. Thought that was pretty pathetic. Pretty sure its still under 100k yet as well. That was with a fresh oil change as well.

**mustang50lx** · 01-19-2009, 10:22 PM

Do you buy your gas at the same place all the time? Fuel in PA. may or may not have up to 10% ethanol. 10% ethanol will make a noticeable difference in gas mileage. Whats the fuel trim read on the scanner? Anything on the plus side means the truck is adding fuel as I am sure you already know. If the long term is hanging on the plus side there may be a problem. Have you tried to flow propane around the intake. A vacuum leak will make the truck add fuel and decrease mileage. Any of this stuff could be not quite right, but not bad enough to flag a code. Did you try to clean the Air flow sensor? I am sure you already tried most of this, but I thought I would throw it out there.

**2000GT** · 01-19-2009, 10:29 PM

Mike,
Although this is a totally different vehicle, our Edge has dropped about 2 mpg since the cold weather. Maybe it is the "winter blend" gas combined with the cold weather.

**v6mustang01** · 01-19-2009, 10:36 PM

I have a 2005 F150 with the 5.4 and 373 gears. Just rolled 62000miles on it and i get anywhere from 14.6-to 17mpg out of it. I havent towed anything. Only thing different from factory is a k&n replacement filter and royal purple 5w20 oil. I dont buy gas at the same place all the time either. but my old truck i noticed when i ran sunoco gas i got about 2mpg less than if i ran rutters or bp gas. I think sunoco does the full 10% ethanol tho. I dont remember what the weight difference is between the f250 and the f150 but shoudlnt be enough to get 10mpg i wouldnt think.
I know its a slim possibilty but u wouldnt happen to have a brake caliper hung up possibly?

**mr4teth** · 01-19-2009, 11:07 PM

I own a 2005 Lariat Super Crew, 5.4, 3.73, K&N CAI , 20' wheels with 20k. From day one I have not been happy with my gas MPG. I was getting anywhere between 10-12 MPG for my first 15,000 miles. Last spring I started running an Evolution tune and not only did my MPG go up (12-17) but the pig actually grew some balls.

I hate to bash Ford but this 5.4 has always been a gas PIG. When I sold Ford's back in the mid 90's all of my F-150 and Expedition customers complained about fuel economy.

**PSPstang** · 01-20-2009, 12:00 AM

i have had 2 05 f150 5.4's and they have both got rotton mileage
my old one was an fx4 supercrew bought new-got around 12mpg city 16 at best on highway. sold with 22K miles

i actually had it to to the dealer once complaining about fuel economy but nothing could be found wrong.

my current truck is an 05 fx4 supercab also gets around 12mpg city, 9700 miles haven't had it on any long trips yet, but i am sure not to expect anything different.

**Flyin Monkey** · 01-20-2009, 06:54 AM

My 5.4 Superduty was getting 12 and my 5.4 Expedition gets 12.

**SonofaBish** · 01-20-2009, 08:08 AM

my Harley F-150 has the 5.4 in it, and i'm not very happy with the gas mileage at all - but from the sounds of it, maybe I should be... its a 2000, with 69K miles on it, and always gets a mix of highway and city driving - and never waivers from about 15 mpg.... it may make a difference that its a 2WD vehicle though? however, doesn't help that its lugging around 20" chrome wheels

I always felt this was horrible, since my parent's brand new Avalanche gets like 18 or 19mpg... it has the LSx based 5.3 .... i guess LSx > Ford.... lol:)

**Stangman701** · 01-20-2009, 09:52 AM

I just picked up an 04 F150 with the 5.4. Haven't even gotten a full tank through it yet, but from the looks of things the mileage isn't going to be too good. Why not let Jon Lund build you a tune. I'm sure he could coax a few more MPG out of it

If you do, post up the results because I was seriously considering doing the same thing myself.

**stieny** · 01-20-2009, 10:13 AM

Yes, as mentioned above, the winter gas always drops my mileage in my truck. Not sure how often you take your mileage but you probably will see a drop during winter months.

**Rodeheaver's** · 01-20-2009, 10:52 AM

Check the intake air temp sensor, those trucks have em in the intake pipe instead of the intake runner, were they should be... check it with your scan tool to be sure it is in spec, you can simply turn on the key in the truck and look at the value of the sensor and compare it with ambient, this will tell you if it is off, but both of my 5.4l expeditions got terrible mileage when it was cold outside, keep in mind to that you are probally letting them idle longer in your drive way in the mournings this time of year.. I know becuase i let my powerstroke get nice and toasty before i leave everyday..

**Wolfpack Speed** · 01-20-2009, 02:01 PM

Seems like nobody gets good mileage out of these pigs! Thanks for all the suggestions everyone, I just haven't had the time to start testing things. I did put in new k&n oem replacment filter and a new fuel filter a while back. I hear everyone on the winter fuel and extra idle time but that has been verified and isn't the cause. I guess it could be many things and I am either going to have to fix it my self or just trade it in like I already was planning. I really don't know what I would get though, the only thing I like about a dodge is the cummins...never had a dodge though. I have had 2 chevy trucks and they are soft and terrible for towing...loved the duramax allison though! My 2 fords were great tow vehicles but I am afraid to buy a diesel from them, they are getting ready to drop the 6.4 some time in the 09 model year. I think I am going to buy a honda civic

**somethingclever** · 01-20-2009, 02:16 PM

WHy not an 09 F150?

Best in-class towing capacity and 21mpg.

**Rodeheaver's** · 01-20-2009, 02:24 PM

I do alot of high flow mufflers and filter kits, If i do a dual exhuast and a k&n (fipk) kit, my customers almost always call me to tell me they see a point or 2 on mpg, i did a highflow muffler and fipk kit on a 07 durango with a 4.7 and this guy swears up and down it gets 21-22mpg now... hope this helps, the reason i said before about the intake air temp sensor, is that i have seen them go a little bonkers and read 10-20 colder than ambient, so that will make her run a little richer, burning more fuel.. hope this helps man!! And I think your right, the only thing good bout the dodges is the engine and the only thing good bout the chevys is the trannys... the trucks just plain stink... those new f-150s are supposed to have some kind of a new load trailor control or something of that nature, it might be an option to downgrade to a 150..

**03 OW SVT** · 01-20-2009, 02:46 PM

Originally Posted by Rodeheaver's

I do alot of high flow mufflers and filter kits, If i do a dual exhuast and a k&n (fipk) kit, my customers almost always call me to tell me they see a point or 2 on mpg, i did a highflow muffler and fipk kit on a 07 durango with a 4.7 and this guy swears up and down it gets 21-22mpg now... hope this helps, the reason i said before about the intake air temp sensor, is that i have seen them go a little bonkers and read 10-20 colder than ambient, so that will make her run a little richer, burning more fuel.. hope this helps man!! And I think your right, the only thing good bout the dodges is the engine and the only thing good bout the chevys is the trannys... the trucks just plain stink... those new f-150s are supposed to have some kind of a new load trailor control or something of that nature, it might be an option to downgrade to a 150..

I have an 08 GMC Seirra with the 5.3 and 3:73's and it pulls my 7by14 enclosed trailer just fine. I get about 10 to 12mpg pulling it (the trailer) loaded with 5 to 7 thousand lbs everyday. When its not pulling the trailer it gets about 18mpg or so combined driving and 22mpg highway.

**Wolfpack Speed** · 01-20-2009, 03:42 PM

Tires are new but problem existed long before them, dating back to last summer actually. I know there are little things I can do to up the mileage and I would have done them if I had planned on keeping the truck. What jacks me off is the truck was bone stock and out of knowhere the mileage goes nuts!!!!!!! It wasn't great before but 8-9 city is BAD!!! I only get 6mpgs when I pull my 24' trailer!