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Discussion Starter #1
OK so my dad has a 06 F-350 with almost 42k on it. its an extended cab long bed, and right now the only real weight in it is his tool chest that weighs about 400lbs. Where we're worinking is about a 90 mile round trip and all highway. Yet he is only getting 11.9 mpg. Sometimes a little better. So my question is what might be the problem? could it be that it needs an EGR valve cleaning or what. I know it should be getting at least 15 i would think. Any ideas are welcome
 

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When mine was stock I was getting 22-23 and sometimes 24mpg. Somethings definetly wrong with his truck, could be a number of things. Start with checking the fuel filters and go from there.
 

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Discussion Starter #3
probably should have said that, he has changed the fuel filters within the last 10k for sure, so what else could it be?
 

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what all is done to the truck or is it bone stock?
 

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:popcorn2:
 

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:popcorn2:
 

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Discussion Starter #7
yeah everything is stock, expect for the previous owner put an AFE stage 1 intake on it.
 

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What trans does he have? Is it the 5R110? Is he running in Tow/Haul Mode - that would make for a difference (lower) mileage - though not a big difference.

What speed is he running at - my best mpg mileage is around the limit to 65 (55-65) much over that and my mileage starts to drop significantly.

Is his truck 4wd? Are his front hubs manually locked in? Locking them in manually - even if not switched in 4wd in the cab - will contribute to lower mileage.

When is the last time his oil was changed? When I went synthetic - I picked up 1mpg.

Does he run any additives in the tank? I run a mix of DieselKleen and 2-stroke oil in every tank. Mileage gains there too. (little)

All these things are little items that a couple of them together could add up to a few mpg drop or gain.

If the EGR is stuck - the truck would be puking black smoke and choking on acceleration from stop. You would know something is definetly wrong.

check the air filter - is it dirty?

Stop by Autozone and have them pull the codes - even if the check engine light isnt on - might be something lurking in the computer.

My last jaunt was over the weekend - 223 miles and returned 22.1mpg. I kept my speed between 60 & 65 while punching it a few times for fun. My truck sounds like yours minus the year. Same body style. Mines an early '03 with 6.0 and the Banks Six-Gun tuner and I have 33" tires, and a shell from an OBS Ford and 194,000 miles.
 

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Discussion Starter #9
alright i'll have him check some of those things out. Thanks for the help
 

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If the EGR is stuck - the truck would be puking black smoke and choking on acceleration from stop. You would know something is definetly wrong.

QUOTE]

oh yeah. my 05 350 was doing that and the fuel mileage was between 13.4 to 13.7.
i dont know if others do this but mine shows the MPG on the trip meter. engine hours too. we took it to the dealer after we pulled the codes and they replaced the EGR cooler (which was still under warranty so i guess it had never gone till we got it which was 3 weeks ago) and just got it back today and it was getting about 14.5 on the 4 mile trip from the dealer to the house
 

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Is your dad's truck a dually because if thats the case it may have lower gears than a 3.73 which might be your mpg killer?

Just my :twocents:
 

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Discussion Starter #13
Any other ideas?
 

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Hmm... I get 14.6 on the highway with 285s...

But my EGR is probably ****ting itself... My ICT iirc is also leaking... my filter is dirty and so is my oil...


Otherwise... I usually get 22 on the highway..
 

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The 6.0 should be kept below 2000 rpm for decent mileage. Chances are, on an f350 at highway speeds of 65, you're way over that. Check it out next on the next ride.
 

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Discussion Starter #16
no its a SRW and as for the speed on the highway he doesnt go over 65. ever lol
 

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I never drive slow and with 35s 4 inch lift the best I can get is 15-16 doing 80-85 on the interstate. Never drove slow to see what I got there. I think some just get better than others. My old 7.3 I could get 20-22 and all my buddies and people I knew could only get 15-16.
 
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