Fuel Mileage questions I know I know!!

zilla68

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Do any of these items affect fuel mileage?

My truck in my sig gets less than acceptable mileage 10.8 last time I figured/fill up. I replaced the mechanical pump as it was leaking and thought I might gain some there, maybe the .8.
Is this all I'm destined to is 10.8 ish? unloaded

Hpop

icp

ipr

injector orings

I did a buzz test a few weeks ago with my mt2500 scanner and they all sound exactly the same, sounded strong actually.
 

woodduck97

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I would look at getting some new injector orings or new injectors. I am pulling about 15mpg with 300/200 injectors.
 

cowboy_dan

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Worn out injectors could drop mileage, but I wouldn't expect it to drop that far.

What are your driving conditions?
In the city back & forth to work (~8 minutes), church & back (10-14 minutes), and general errand running around town (never gets over 45mph and usually not over 35mph), I get 10-14mpg depending on weather, fuel, traffic, and my own aggressiveness.
Now, on the interstate with cruise set at 70, I generally get 16-18mpg. On the way from Memphis to Racine (via my parents near Indy) last week I ran 65 all the way and got 19.25.

Do you have a pyrometer? If not, then get one. Unless you're getting on the interstate, keep the EGTs below 600 deg F. You'll have to back off the skinny pedal a long way to do it, but I found it still gets reasonably good acceleration in traffic at that temp.
EGTs are a really good way to see how hot the cylinder is getting. Higher EGTs mean higher cylinder temp. Higher cylinder temp for the same speed means more fuel is being burned. More fuel being burned means worse fuel economy.

The HPOP doesn't make much difference in mileage running around unloaded. If it did, my mileage would be in the sewer because I have a pretty weak pump.
All the IPR does is regulate how much oil is allowed to be dumped back into the reservoir to maintain the desired pressure. Not much it can do to change mileage
The ICP sensor is just that, a sensor. In theory it might change mileage if it were giving a false reading, but the engine would also probably run like crap or be really noisy.
 

zilla68

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Here is the kicker, I only drive my truck on the weekend (usually saturdays), towing a 12 ft lawn trailer with 1 zero turn, 3 weedwackers, a push mower etc. My jeep tows it ok, so its not heavy, single axle at that.

I do have 3 gauges, pyro, tranny, and boost. I keep it right at 60 and my trip is usually about 60 miles round trip. Pyro runs around 600-800 max keep boost out of it, usually at 0-5 if that, 60-65mph is at 1500-1650rpms.

Plus its 4x4, so I'm sure that's not helping at all, but I'd think 15 is doable in my truck.
 

zilla68

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I'm also in the process, as time allows, to change out the orings, I have them on hand, just haven't done them yet. I'm wanting to do 1 thing at a time, to keep track of mileage, so if it changes I'll know what it was.

hpop was next on the list.
 

woodduck97

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could you describe your truck for me?

Well my truck is a 1997 F-250 4x4 186,000 miles currently, 4.10 gears with lots of modifications. A working progress I call it LOL Before I started all the mods on the truck I ran it stock for about a year after buying it and got the max of 17mpg on the highway and about 13 around town. Then got a DP tuner chip and didnt notice much MPG increase. About a year goes by and I decided I want bigger injectors so I go with stage ones and also change chips which is TS chip with Matt at Gearhead Auto's tunes at the same time. MPG went up almost 3 gallons after the install of the new injectors. I could get about 15.6 daily driving it and romping on the throttle still.

Sold those to black974door on here which lives 5 minutes from me doing the speed limit. His truck is also a 97 but has 3.55 gears with about 200k on the clock and he was averageing 12mpg or less with his stock injectors with bad orings. After the install of the stage ones he averaged 18mpg daily driving it and about 23 or so on the highway.

If money is tight I would first try installing just new orings and seeing where that gets you. If money does not matter I would see about upgrading your injectors or getting another set of stock injectors from one of are site sponsers.

Also what is your driving conditions?
 

zilla68

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mostly hiway, I don't have enough mods to stomp on it with any success, lmao!

I need to tackle those orings then and see what happens. I will be doing injectors but not for a while, I thought I'd do a hpop first.
that mileage is unbelievable to me, I'd kill to see 18, but I don't think I could get that if I pushed it down hill.
money does matter, got to do a little at a time, especially since its not a daily driver, but if I could see mileage like that, I'd drive it everyday for sure


or should I go injectors first, then hpop, I just figured with 174k on the clock it might be tired. It was never a heavy tow pig for the last 10 years at least, I know the PO and he didn't tow much more than a sandrail/quad's on a trailer, maybe a bobcat 1 time, basically a daily driver for him also, but he lives 1 mile from work, lol.
 

woodduck97

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I just sent my stock HPOP out with 186k on it and only set the SES light twice with the stage ones and none with the current large injectors. I would deff do injectors before HPOP imo. Also I just noticed you have the 1.0 turbo housing. That will also lesson your MPG because it will build more boost while cruiseing down the road and calls for more fuel. Had the 1.0 housing and got rid of it. Also noticed I had higher egts with it.
 

woodduck97

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I don't think his tire size is playing that much of a roll they are only 285/75/16. Black97 and me are both running the same size and still better mpg.
 

woodduck97

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Tires is not your problem. Injector orings or injectors is the problem more then likely. Maybe jack each wheel and see if it spins freely and brakes are not dragging.
 

SDS97_7.3

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Tires shouldn't be a problem. I run 315/75/16's and towing a heavier trailer with more weight then you have, I was getting 15mpg, with 305/75/16's I was getting 16mpg or so
 

StrokerTurbo7.3

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I get 12.5 in the city pulling my landscape trailer and mowers around. Never getting over 40mph with wheels/tires in sig, 4:10's, and i'm fairly sure my injector o-rings are on their last leg as well.
 

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