I've had my f250 (pre-1999, 7.3L) for about 5 months now . . . And I'm getting only about 13.7-14.0 mpg. Granted I drive around the city for the most part . . . but it doesn't seem to matter whether I'm heavy on the pedal, light on the pedal . . . I could pretty much go to vegas and gamble on how likely the mileage will be between 13.7 and 14.0.

So, is this normal? I put on a 4 inch straight pipe(which should be better mileage) . . . I've got 305-75 load range E tires, inflated around 54psi or so. I put in an aftermarket filter, it is not K&N, but it is an equivalent setup that is nicer I think. S&N might be the manufacturer?? I have the superchips tuner, but right now the truck is NOT TUNED . . .

Does anyone think I should tune the truck and see what difference it makes?


Oh yeah, I've had a HPOP leak for the last 3 months. Finally decided to try and fix it myself. I did that yesterday . . . still leaking today, but not as much . . . I'm thinking some oil is still left on top of the engine that is still dripping down looking like a rear seal. Could the HPOP have any affect on the mileage?


Thoughts, ideas and opinions would be greatly appreciated. Thanks.

 

Welcome to FTE!

Is it a 4x4?

I usually get right around 14 or a little higher in the city, but you should see some improvement on the highway, 4x4 or not.

Check for boost leaks around the I/C boots and on the up pipes. There are a few other things people will list that I have forgotten. Rough day today!

 

With those tires could i assume you have a lift? Either way that milage is not far off with that size of tire. you could improve your milage with the right tuner, DP or PHP come to mind but there are a other ones. Talk to Clay at RiffRaff, he will steer you right. Roy

 

Thanks for the replies. Truck is 4wd. Truck is lifted, but only a leveling kit, so maybe 1.5 inches at the most in the front.


Tuning it would help eh? Ok. I have the tuner, but I've been scared to because of all the talk I read about with exhaust temps and such. I know I have the right exhaust to tune it. (4 inch down pipe all the way to the 5inch tail pipe)
And I have a great air filter. And to boot all that, I have the exhaust temp gauge and the turbo boost gauges . . . just haven't installed them because I don't know how and I don't trust the local Mexican repair shops to know how on my diesel.

So, do you think it is safe to tune it and run it conservatively without my gauges being installed yet? And, do you think I can install the gauges myself without trouble?


So basically guys with 4x4s and big tires are claiming 17-19 with these rigs? I've seen some people claiming it, and I don't really see how it is possible.


Lastly, it was mentioned the I/C boots and the up-pipes. How would I check those and what exactly would I be looking for? No one has made a comment on the HPOP leak factoring in, so can I ignore that as dragging any mileage out of my truck?


Oh yeah, any thoughts on going synthetic in my transmission and my differentials? Seems to me that could show a sig difference.

Thanks a ton.

 

i have a 99.5 4x4 cc with 285 on lift and i got 14.5 then i replaced the EBP and tube and it is 17.8, if you don't have a code it may not be that but it is simple to pull and see if it is clogged.

 

Your numbers are better then what I see around the city. I have the 4x4 CC, LB,with cap, running on 315's
The best I have seen on the highway has been 17.25. This was done with a 4" open exhaust, a 6637 air filter and a DP on 80 eco.
And now that we are on winter blend.. I will be watching.

 

What is EBP and tube? The superchips tuner has a code reader built with it. I'll go check to see if I have thrown any codes . . . I had a couple a first, but cleared them, and they hadn't come back. I don't remember what they were . . . but I'll post them when I find out.

17.8 seems unbelievable . . . wow! I mean, the difference in a 285 and 305 tire isn't too much for most brands. But then again, your original mileage is about what I'm at.

I'll get back with any codes, and please advise on what the EBP is and how I would check it. Thanks.

 

EBP is exhaust back pressure pipe and sensor. Here is a guide for cleaning :

Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

I run 315's with a front leveler and get between 16 and 17 mpg pretty much all the time. Mostly city driving with little hwy here and there. Check my signature for every thing I have done. Along with EBP, check some of the other regular culprits, fuel filter and leaky up pipes.

 

here is the link, exhaust backpressure sensor and tube
Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

 

17.8 around town is more than above average, but about right for combined average if you do a bit of fwy driving.

You will loose a mile or two with 305's mostly due to road friction and a we bit to air drag (larger frontal area). Lift will only hurt a tiny bit at 1.5" but it all adds up.

14 mpg around town is typical from what I have read and experienced. You best mpg improvement is allways the 2x4 fix. Stuff a 2x4 under you go pedal and you will see a 20% improvement and you will get the unique experience of being passed by a 67 vw micro bus on the hills. Not worth the extra mpg. These are HEAVY trucks that take a lot of juice to get up to speed, once you are there they are not bad, (my old 4.9 v6 f150 2x4 got worse mpg in town), but who wants to be passed by grandma?

Do a search for EBPV (exhaust back pressure valve). This is a valve designed to help warm your engine up to operating temperatures by creating backpressure at the turbo. When it is on in kills you engine efficiency and you motor sounds like a a jet engine with a cold. It is not supposed to engage under heavy load or when exhaust temps are above xyz. This valve is also a source of oil leaks for most of us which for some (self included) is the final straw to just gut the ebpv or delete the darn thing as it does not get cold enough to justify it's use.

There is a tube coming off the passenger manifold that leads to a sensor down by the fan pulleys that sometimes gets clogged. Do a search for ebpv sensor and you should find the step by step to walk you through it. Good luck and welcome to the site.

 

Terry's #1 mpg increaser is his bed cover. it is usually good for 1.5-2 mpg increase. all the other stuff helps too. I get roughly 15-17 depending on my right foot, and I hot rod alot

 

i have a top on mine, not all in town 10 miles and 30 on the road, so that helps and i run DK and i drive good most of the time

 

I just got back from a deer hunting trip and averaged 15.65 US mpg's. I kept the truck at around 1700 rpm's for the most part on the hwy. But there was a fair bit of time in 4x4.I use synthetic fluid in my diffs, engine, T- case and tranny and have had no problems,touch wood. Oh yea we got four nice 8pt mulies. Roy.

 

Did you replace the sensor as well? Or just try to clean it?

I cleaned my sensor, but replaced the tube. First cold morning today and my EBPV is only partially closing. The hiss, not the roar, is back!

 

I cleaned mine, but you have to be careful since its very fragile on the business end.


I don't use synthetic anything, but only because I'm cheap. Next time I'm up for a major fluid change, I will probably swap to synthetic.

I haven't gotten over 18mpg in a LONG time. Usually mid 17's on highway these days, but I do have my bed cover off...never really thought about that, but I will be putting that back on this weekend anyways.