I get 20 on the highway.....in town really varies, depending how much stop and go, etc, etc. But never below 13 in town, and that was hauling bark dust, then some junk for my brother. You have something not right going on. 5w40 synthetic helps mileage, as do stock tires, proper inflation, no leveling kit, make sure brakes aren't dragging. The turbo howling may be the issue. Air filter? Checked fuel pressure? FICM voltage? Winter fuel or bio diesel will kill mpg's as well. Whatever the cause, it's better to find it now in case it ends up being something catastrophic or leaves you on the side of the road with a higher repair bill.

 

I have been fighting this as well. I drive less than 10 miles to work and I get less than 11MPG. I get 13 on the HWY towing my 8000# TT. I have failing head gaskets and I believe a couple of injectors on ther way out as well.

 

10 miles to work doesn't even warm up the oil.....less than 11 mpg is probably normal. 13 while towing 8000, sounds acceptable. I tow a 5000 lb boat trailer, lousy aerodynamics, and get 13-14 at 60 mph.

Failing head gaskets??? I assume you did a pressure test to confirm, and no egr cooler to have leaking inside? Keep in mind, puking under load is not always head gasket. It can be a plugged egr cooler, insufficient flow through it, coolant overheats inside and turns to steam. Can also happen from oil cooler in same scenario.....coolant headed to egr cooler too hot, boils in the egr cooler. End result is the steam vents out at the cap. If egr deleted, then probably is the head gasket.....

 

If you have a New strategy the issue is not really the ECM strat but the FICM code. The older non inferred strats are better at boosting (throttle response which helps mileage) but the newer inferred codes are more consistant. Also the new FICM code hide injector issues really well and cause the greatest power and leage loss. (I know because I fought a mileage issue and didn't find which injector till I put a FICM tune on it) Personally to start with mileage issue without a shining issue I would do these things.

change to a good 5w40 oil, run a go of revx, and look at a mild FICM tune from IDP or PHP. These did the most for mileage in mine and finding the bad injectors. Once I replaced the injectors my mileage really got better. There can be other things but If I end up picking another one up these would be the first on my list.

 

change to a good 5w40 oil, run a go of revx, and look at a mild FICM tune from IDP or PHP. These did the most for mileage in mine and finding the bad injectors. Once I replaced the injectors my mileage really got better. There can be other things but If I end up picking another one up these would be the first on my list.

I'm running t6 5w-40 and I just put 8oz of revx with the oil change about a month ago now. Now my mileage did increase I also installed a oem y pipe and up pipe (they were cracked).

Not sure if a tune is the answer here. I say that because stock trucks are getting better then 13mpg in town. I drove on the interstate and reset my mpg meter and the best I got was 16.7 doing 60. Not pulling anything. Could a low voltage FICM be the reason for my ***** mileage?

 

I plug mine in and when I start it, my ECT and EOT are over 130F. They both eclipse 190 before I pull into work, bit they're not there very long...3-4min probably. Twice a week I take a much longer route home that takes 30 minutes.

 

Probably a good thing. I did an oil cooler and egr delete, cat delete for my elderly neighbor, 6 months after Ford did the oil cooler. He can't afford their labor anymore. Less than 100,000 miles, had Ford Gold. He didn't realize his driving style is why this was happening. (One turbo every year as well!) He starts the truck up, drives 1 mile to the store, comes home and shuts it off. When freezing out, never plugged it in...idled for 20 minutes instead! Furthest he drives is 6 miles, once every 2 weeks. Doesn't want to part with it for a vehicle that can handle the 'extreme service' cheaper, so he now leaves it plugged in, has 5w40 Rotella, and he's ordered the same stuff I have on my truck. (Oil and coolant bypass) He also babied it. After we did the work, we took it out on the highway for a hard drive. Took several WOT's to get boost past 15 psi.....and clouds of crap that was in the exhaust. After he was convinced we have destroyed the engine, he got behind the wheel and realized it's never idled so well. Hadn't been that responsive since new. He now takes the long way to the store, about 6 miles, and hammers on it once or twice......nice to see the 72 year old guy with a smile now, and he's talking about adding gauges!

 

I gave up on mileage. When I first put my tuner on with my truck stock height I got 19 hwy-16 town, then when I put my leveling kit it went to 17 hwy-15 town, and now that I put 305's with 2.5" spacers on the rear it barely gets 14.5 hwy and 12.5 town. That's running 5w-40 T6 and archoil with custom tunes :/


Sent from AutoGuide.com App

 

i get 14.2 citydriving during the summer but with winter and warm up time its down to 13.4 have never takin truck on a trip but in 17 days it will be on its way to daytona pulling a 18ft. trailer with 4 bikes it should stay around 14 mpg i hope

 

I had an injector code #4 issue for about six months with truck being hard to start and running rough till about 160*. I changed the oil and did the Rev-x thing hoping it would do it's magic again to no avail. Then injector 6 code started popping up. FICM voltage all along was showing 46.5 and up. Then FICM started dropping to around 44 every so often and then crashed to upper 20's. Ed sent me an exchange FICM, so I could still use my truck, with the Atlas 40 tune. Changed nothing else, the inj. codes went away, truck would start with no issues and went from 12.5 mpg's to 15-16 mpg's in the city. After going through this I would assume FICM tune would help mpg's. I'm not a mechanic, just my .02. Hope this helps.

 

Same issue here! I only get 12.5 straight highway only doing 65MPH. I limit myself because I have 4.56 and 37's but around town I get maybe 9mpg. Sucks! It makes abosolutely no diference tuned or not.

I am not sure exactly when it happened because I never use to check my milage that much but at one point I got 16.5mph highway. When I look back, I think it was when I updated my PCM and FICM at Ford.

My friend purchased the FICM tuner from Innovative and it is a little snappier but he has only had it a week or two. If he notices a difference in mileage, I will buy one for sure. i drive all over Ohio for work and I am loosing money.

i hang out with 6 people who drive 6.0's and they all suck on fuel but all of them have been updated because back in the day, we didnt know any better.

 

I have issues with mileage as well dropping significantly from 15-17 mix driving to 9-10 mix driving I have a 58 volt FICM but the the FICM code is on the when I pull the codes along with Turbo underboost code it runs 30-35psi and is an ATS S3000 turbo non VGT, Stage 2 Elite diesel injectors I dont know who did the FICM but on cold starts the FICM reads 47 volts til the glow plugs shut off and battery voltage goes up too 13.8-14.1 then it reads 50 volts which is ok because I read the factory computer wont read higher than 50. If I leave it in the garage over night and start it it never drops below 50 during cranking or operating temp but outside she drops in the cold, and I'm talking cold with windchills in -10 to -35 degrees? Is FICM my issue? I have 37s and an 8 inch lift so I was really happy with my 15-17 mpg. that was one of my main reasons in buying a diesel because my buddy has gas lifted trucks that get horrible mileage, but the guys with lifted diesels get much better economy, I only bought a diesel for that, I dont tow much but I wanted a big truck that got better than 10. I have 4 pin FICM if it matters, sorry for the long post and semi thread jack

 

I would think that the underboost coade may be due to not having a VGT acctuator. Other than that, I'm at a loss.

 

thanks, when i bought the truck it had no codes! its really frustrating spending that much on a vehicle and just doing repair after repair! I had sudden loss of power was doing 72 mph with cruise on, cruise kicked off and lost power, pulled off read the codes cleared them and they wouldnt clear truck still has lack of power but no check engine light, the inector number 4 code only comes on once a month maybe? but the turbo underboost and FICM poor performance code are always on so I thought they could be related?

 

I know I am sort of bumping this back from the dead but I was curious about a few things due to my truck getting around the same mpg. When I cold start the truck my ficm main voltage will read in the upper 30's but after the truck warms up it will read 47-49 consistently. The truck throws no codes and has a catless 5" mbrp exhaust and an sct livewire ts running on the performance tune. Im still only getting around 11mpg in the city babying it. Any info on the ficm or what you think could help or what to look for would be appreciated.

 

Well...interesting thoughts on the FICM and fuel mileage. I installed my digital voltmeter in the dash this past week. (My average highway on a 330 mile round trip to Seattle was 21.3 mpg...a new record for my truck, cruising at 65 mph freeway most of the time and on winter fuel!) My FICM never goes below 48 while starting, and with engine running is always 48.2-48.5. This is a stock FICM from 2006 with 174,000 miles on it now. Alternator charges at 14.2 as you can see on the other gauge. I have these wired into an upfitter switch so I can switch them on and off.

After reading the previous posts, and checking my own FICM voltages...I think there is a correlation. I also have 2 fairly new Motorcraft batteries, 100 month 850 CCA's each. They stay at 12.6 volts after sitting overnight with the alarm on, LED flashing.

I'm also stock height, stock tire size, SRW, only running a tranny tune so I can switch the egr CEL off. My cat ran away, egr went with it.....otherwise completely stock except for side steps.