TERRIBLE FUEL MILEAGE

[ckyguy68]

My 05 6.0 has a MBRP exhaust and street tune from innovative. No code, 48 volts @ FICM, runs awesome.

I average 8mpg city on straight fuel and around 10mpg with diesel kleen+cetane booster. That is with a light foot and seeing WOT for a few seconds once a day.

What in gods name could be causing this? I bought the truck expecting to be getting 13 city all day.


wanted to add:

fresh rotella 10w-40 every 5k, fresh fuel filters every 15k

SCT says my coolant temp is around 186 once warmed up fully. I heard the thermostat doesnt open until 190+???

[scha0786]

you coolant temp is good, normal running is around 188F when it gets hot out or you start working does it climb up over 190 but not by much usually

[bfrank81]

I have the same truck but stock tune and I just filled up this morning. I avg 14.7 on my last fill up. I drive 70/30 highway/city. Besides the tune the only thing I am doing different is I'm adding about 28-30 oz of 2 cycle oil at ever fill up. I run that and then will do DK about once a month. Seems to work well for my truck. I would also change your fuel filters at 10K but that's just me.

[Galaxie]

Where do you live? The fuel maybe? The witner mix up north sucks.

[ckyguy68]

I live in Michigan, and my gas station buddy said we are still on winter fuel.

Thought i would also add that my truck has 76,000 miles on it and I do also run 2 stroke oil. Saw negligible gains in MPG but it really quiets the truck down.

[caissiel]

I get 14MPG towing a 15K RV, The truck fan speed is also calibrated at 195F, And the turbo pressure is at 10PSI. I found out that the fan will calibrate temperature at 190F when programed stock and if the thermostat does not alow the water temperature to hit 190F you are running the truck with a closed turbo and fuel enriched to heat up the engine to 190F.
You will never know where your fuel lost is unless you have the Scangauge to indicate the bad fuel mileage.
I read many Forums and every problem I see can be found an resolved with a running gauge that will tell FIMC volt, EOT, Instaneous MPG, Fan Speed, digital Coolant temperature.
So A gauge at $160 would surely pay for itself in a little time as it did with mine.

[ckyguy68]

Originally Posted by caissiel

I get 14MPG towing a 15K RV, The truck fan speed is also calibrated at 195F, And the turbo pressure is at 10PSI. I found out that the fan will calibrate temperature at 190F when programed stock and if the thermostat does not alow the water temperature to hit 190F you are running the truck with a closed turbo and fuel enriched to heat up the engine to 190F.
You will never know where your fuel lost is unless you have the Scangauge to indicate the bad fuel mileage.
I read many Forums and every problem I see can be found an resolved with a running gauge that will tell FIMC volt, EOT, Instaneous MPG, Fan Speed, digital Coolant temperature.
So A gauge at $160 would surely pay for itself in a little time as it did with mine.

Very interesting. I have access to a Ford VCM/IDS so i will take a look at all those PIDs.

With a custom tune from eric can i still use the sct to change when my fan comes on? I've never really heard it come on but just to be sure maybe I can bump it up to 200.

I noticed a couple weeks ago when we had a 85 degree day (thats michigan for ya) it seemed to run better and wasnt drinking as much fuel.

[HeavyAssault]

Have you had the PCM and FICM reflashed? Are you the original owner?

[ckyguy68]

Originally Posted by HeavyAssault

Have you had the PCM and FICM reflashed? Are you the original owner?

My vehicle strategy is VXCF7N3. It was flashed to the most recent ones in 2009 i believe. I am the third owner and have reviewed the Oasis reports and the previous owner has receipts for all the maintenance items. He took very good care of it but said he never paid attention to mileage.

[HeavyAssault]

I'd call Power Hungry Performance asking about that strategy. They can do roll backs on the PCM and FICM. I'm running VXCF4M3 and PHP FICM tuning with great results for mileage. My winter time stats are usually 14mpg +/- mixed driving and climbs into the 16's mixed in the summer. Your reported 8-10 is WAY below normal I'd expect 12 where you live. OAT does play a big part in overall MPG numbers.