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7.3 @ 20-21 MPG?

34K views 71 replies 48 participants last post by  Bamaman1 
#1 ·
Hello, I just bought my first diesel. As I tend to buy things, I went to the biggest and best. 2002 F-250 Crew Cab 4x4 Long Bed with a topper, and the 7.3L Powesrtroke Turbo Diesel. I bought her in Ohio with 119,000 on her, drove back to Georgia after filling up. She went about 650-670 miles on 32 gallons, not completely sure because I drove straight through without a break and that's when I pulled over for a power nap. Unfortunately after I filled up, I reset the trip meter in my tired state. To my knowledge she was driving stock, is this normal? There is a Banks Six Gun hidden under the dash (the dealer didn't even mention it), and when I found it, it said error. So I'm sure it wasn't on while I was driving. I was amazed! I was driving about 70-75 MPH the entire time @2,000-2,200 RPM's. I am about to go to Ohio for Thanksgiving and just wondering, is this as good as it gets... Or will upgrading my intake and exhaust bump me to about 23 MPG? I was looking at the K&N system and a straight pipe. I don't know what pipe is best though, and would like a little input from more diesel experience. Also, would getting the Six Gun operational help? Any help would be awesome. I was driving a 2 door coupe before this that only got 16-18 MPG interstate LOL.

Thanks guys! (and girls):thumbsup:
 
#3 ·
Lol, is that what you would get 444? Wow, so I guess mine is doing better already... If you meant that I should be getting around that amount... I'm just asking if an intake and exhaust set would help me get more than my 20-21 I already get... Didn't mean to bring the sarcastic side out of people in here lol
 
#4 ·
Best I ever got with mine was 19+. That was only once and my speed was less than 60 mph the entire time. The worst was about 11. I would say if you got what you claim, it may be a fluke. One thing about that engine I have found is that everything affects the mileage. You foot on the pedal, outside temp, speed, load, wind and there are probably 20 other things I can't think of right now. The only consistency with this engine is it inconsistency with mileage.
Jim
 
#5 ·
wow, for my sake I hope it's not a fluke lol... It was kinda cold, quite a few semi's on the road, cruise control was broken so I had my foot in the same spot for hours lol... So I guess I have a long time ahead of me keeping track of inconsistent mileages lol. The topper most likely assisted to a degree I'm sure, it's an ugly topper, but now I'm afraid to take it off lol...

Thanks guys:thumbsup:

Anyone else, just keep em comin... :roller:
 
#6 ·
I've had my truck since June, and I regularly get 19-21 hand calculated in mixed driving on my commute. But my truck is a 2wd 6 speed manual and I drive it to conserve fuel. Only mod at this point is a straight through 3.5" exhaust. I regularly can drive 600+ miles on a single tank of fuel which allows me to fill up once a week.
When I romp it stoplight to stoplight, or get on it more in traffic, then my mileage drops down to 18. I'm looking at a chip to help improve my fuel economy (at least after the novelty wears off and I'm done trying to race around).
 
#7 ·
no one has told you but stay away from a K&N filtrer set up... if your on the cheap you can make a 6637 filter assembly and a walker BTM muffler.. if you search here you will find alot of info on them
 
#8 ·
She went about 650-670 miles on 32 gallons.
That's over 20 MPG at over 70 MPH. I'm a skeptic.

Did you fill up though the foam until you could see liquid diesel at the cap? Both before and after that leg of the trip? Is your speedo calibrated so the tripmeter is accurate?

I bought mine new and have done all the normal things to maximize fuel mileage. Stock-size tires, 4x2 drivetrain, economy tune, free-flowing intake and exhaust, calibrated trip meter so I know the miles are accurate, grossing around 8,000 pounds when unloaded without a trailer. The most I have ever seen on an unloaded highway trip cruising at 73 MPH is a hair over 16 MPG, and that was only for two legs that were years apart over the last 11+ years and 192,000 miles. It usually gets 14 to 15 unloaded, and anywhere from 8.5 to 12 when towing - depending on speed, terrain, and wind.

So if you really are getting ove 20 MPG, then be extremely happy and don't hope for better than that.

On mine, the tune, exhaust and intake mods didn't improve MPG. Your mileage may vary.
 
#9 ·
It usually gets 14 to 15 unloaded, and anywhere from 8.5 to 12 when towing - depending on speed, terrain, and wind.
I know I am running an old IDI..But I guess I need to be happy with my 14 MPG empty and 10.5 MPG pulling on the flats :thup: (E4OD, 215/85R-16, 4:10 LS)
 
#10 ·
the trip computer mpg is not always on the money. i suggest hand calculating. as suggest above be sure to fill tank to same point everytime.

in town i usually get 15.5mpg. on the highway at 70mph i usually get 17mpg. if i drive 55mph i get 19mpg on the highway. 55mph is way to boring and makes me sleepy. so i sacrifice 2mpg.

i have found diesel fuel quality greatly effects the fuel mileage. i get the best mpg on sunoco fuel. the stations pump filters play a huge part in fuel quality too. the extra penny or two is sometimes worth it for fuel.
 
#11 ·
I have regularly gotten 20mpg at 70mph in Colorado. As 444 mentioned, it drops quickly at higher speeds. I have never gotten 20mph at lower elevations (trips to Texas, California, etc.) so I know wind resistance plays a large part. My typical highway trip in Colorado is at 5000-7000 feet above sea level. Thin air helps a lot. I hand calculate and buy my fuel from Valero or Shell. Other brand fuels available locally burn noisy and produce less mpg.

My highway fuel economy dropped by at least 2mpg after I put a tall topper (camper shell) on the truck.
 
#12 ·
I got 13-14mpg when it was stock, now get 17-18 @ 2000-2100 rpm.

It only took me about $6000 to get it there.....:(
 
#30 ·
I got 13-14mpg when it was stock, now get 17-18 @ 2000-2100 rpm.

It only took me about $6000 to get it there.....:(

LOL . HEY at least you had fun .


What would be the math formula to calc fuel milage mod vs payback time ?
 
#13 · (Edited)
I bought mine new in Nov, '00 and have watched MPG since day one. Mine is 6 spd, 2WD, LWB with a Glasstite cap. The truck is bone stock except for a Ford AIS air filter and Kim Lux injectors I installed in '01 soon after I bought the truck. I don't have a computer so when I want an accurate no. I do as Smokey said and fill up past the foam until I see liquid almost at the spout. I have not had my speedometer calibrated, so I can't certify my numbers. I routinely achieve 19+ MPG at 70+ MPH. I found that by cruising at 2000 RPM (approx. 67-68 mph) my mileage goes up to 20+ with a recent tank at 21.1. I went 750 miles before filling up...95% hiway. The worst I have ever gotten not towing was 16+ around town. I haven't towed enough to report, but I did tow a 5000# boat from Eastern Maryland to Columbia, SC (573 miles) and got around 12.5. As a point of interest, I can usually add 3.5-4 gallons after the automatic fuel pump stops...takes another 5 minutes or so for that last few gallons.
I'm gonna keep it until it dies or I die...I'll probably go first.
 
#14 ·
I would say check it a few times before you count on that being accurate. You can easily add 3-5 gallons more after it clicks off the first time on most pumps. That makes it easy to be inconsistent in the amount of fuel you put in. You could milk the last 5 gallons in on one fillup, drive till empty, then stop at first click next time, and have an outstanding mileage figure-but it won't be accurate. Best way is to keep up with it over several thousand miles on a tablet in the console. Over 1500-2000+ miles, a couple gallons difference won't affect your numbers as much. My problem is I can't stand to drive for mileage for more than one tank, and usually not even a whole tank lol. This thing's just so much fun to drive when tuned :D

I can get 18-19 around town out of the truck in my sig, and can milk 20 if I try really, really hard. But that's no fun. I'd say highway, unloaded, it may get 22 if I keep rpms at or below 2,000, but I don't know. It's always loaded on highway trips, getting about 12 with the camper. Otherwise we take the 35+mpg 4cyl car. 21 highway is very possible, but at 75 mph, I highly doubt it. At 70, maybe.
 
#15 ·
The best I ever got was about 19.5mpg on a trip. I used to regularly get 600 miles per tank. I have not seen that in long time. Not sure if it was the switch from stock tires to 285/75/16s or the ULSD, or combo of both. Now I typically get 500 miles per tank. I sure would like to get back to 600 per tank.
 
#16 ·
The best I got was almost 20mpg with my 97 driving cross country.
My 2002 will consistently get 390 - 420 miles per tank (short bed) which makes it between 18 and 20.
But I drive like an old man.
I don't check the MPG very often, but I do reset the trip ODO almost every time I fill it.
 
#17 ·
My latest calculation from a trip I took was 20.23 MPG. This was driving at no more than 65 MPH and keeping RPM's under 2k. I run the 80 HP Econo tune from Jody. I have taken this trip several times and the only real difference this time was pulling the gray cps out and replacing with the OEM black one. With the gray I would get mid 18's.

I always fill the tank to the point I see clear fuel in the filler neck. I have not done the Harpoon Mod on my truck yet, so it takes a bit longer. My speedo is very close to being right, but I have yet to try Smokey's 100 mile odometer check so I will assume it is mostly correct.

Been driving mine for about 7 years. Been in the 20 MPG club a few times, not real often though. I usually have a trailer hooked on when on long trips, so my mileage usually has a lot of mixed driving on it.
 
#20 · (Edited)
The official size of your fuel tank is 29 gallons, but it will hold about 32 if you come in on fumes.
 
#22 ·
I have a 2000 CC, DRW, 4:10. Stock with the exception of DIY Tymar and BTM. I used to get approx 18 mpg hyw empty and 10.5 -11 towing a 12,000 5th whl. That dropped to 16 empty and 9-9.5 towing. The difference was the recall gray CPS. After I replaced it with the dark blue, the mpg has increased to 17 mpg empty and 10-10.5 towing. The only change was the cps. The original mileage checks were using LSD and current is with ULSD.

All of the above was running 2000-2100 rpms. With the 4:10, 62-63 mph. I'm a retired 67 year old fart and haven't been in a hurry for years. Truck has 161,000 on it and runs and tows as good now as it ever did. We're packing to leave on a 3,500 mile trip on Wednesday.
 
#23 ·
Early 99 2wd CC with flush topper, high flow Ford filter, 4" exhaust, SCMT at 60 hp 4:10 diff. Owned since 2003. Commute average maybe 45 mph city/hiway and get around 18.5 mpg. Best was over 20 but at something like 45-55 mph. 70 mph never get over 18 mostly 17 mpg. Worst and I am in Florida is a 20 F day for a week was 14.5 mpg but that is because I drive an average method, not flooring it or babying it.
I have put around 120K miles on the truck since I owned it and it has not changed since day one so what is reported by other members is spot on for me.
20 mpg at 70 mph is incredible...
 
#24 ·
Empty 14-15 mpg and pulling 5k in mountains 12 mpg. All at 65 mph with 4.10 gears and about 2300 rpm.
 
#25 · (Edited)
2000 F-250 4x4 CC swb - From the day i picked mine up at the dealer with 17 miles on it to now with 293,000. I have done the same thing every time i fill up : lock fuel nozzle down and let it auto shut off at 20-21.5 gallons (when empty), then i manually fill it till it is completely full (fuel visible at mouth). If i am not on a low tank , i still fill to top everytime. This is only way you are gonna make sure your calculations are consistant everytime. I have checked my mileage every time ive filled up....alot of paper. From texas to idaho to missouri to north carolina....hauling or completely empty...summer or winter..rain or snow. Best mines ever gotten is 18mpg. averaging 13-14 with a combination of hwy and town driving. that is all stock , with a k&n filter and have always run 35's. Driving with and without cruise at 1900-2000rpm over the road. I would sure like to know what you guys that are getting 19-21mpg are doing !
 
#26 ·
On my commute 35 mile to work I regularly get 13.5 mpg, my truck was badly out of alignment, so I got it aligned before heading from Ohio to Missouri this weekend and I also did the hutch mod. On my way to and from Missouri I got 16.5 mpg:woot: and that’s with the boots on my intercooler leaking and a brake caliper starting to hang up a little. So I’m hoping if I fix that I will be able to get a little better yet.
 
#27 ·
Best I ever got was a trip from tampa, fl, to wells, me. (just over 1500 miles driveway to driveway) 24.8 hand calculated, tires aired up, and cruise set at 55mph. Painful to travel that slow on the highway, but this was also back when diesel was $4 a gallon, so I was more concerned with my wallet than how slow the trip was.

Normal travels in maine I'd average 18-19mpg. Down here in florida, I'm lucky if I can average 16mpg with all the traffic and stoplights.
 
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