Bad fuel mileage 06 6.0

Krgillum0 · Mar 29, 2014

Was wondering if anyone could help me figure out why I am getting bad fuel milage. I have a 06 6.0 90k miles with SCT tuner on street tune, 4 inch exhaust, and running on 33's. Just put new head gaskets on and cleaned the turbo but still only getting 11-12 mpg driving like a grandpa. Any suggestions would be greatly appreciated! Thanks

yeehaw · Mar 30, 2014

How warm is it where you live? My truck does about that with warm up idle. And it never reachs 185 degrees (ECT) when it's below 40 degrees

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Krgillum0 · Mar 30, 2014

I live in Maryland so the weather is different about everyday lol but its been in the 40's the past week or so..I know itll get a little better when summer fuel comes back.. but 130 every 5-6 days in fuel is killing me!

MrOneEyedBoh · Mar 30, 2014

What fixed it for me, is to keep the RPMs up where they want to be. Dont lug the motor, keep RPMs around 1800-2000 and that should get you a bit more. It did for me. Lol and here it is, dont expect to get many more MPGs out of a diesel. Let alone on a performance site, sorry bro. Not going to get much regardless out of these motors.

DarkSide2.6 · Mar 30, 2014

Buy a Honda Civic, that will take car of the $130 a week problem. Tall tires aren't helping either.

-Chris Cayer
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baderic03 · Mar 30, 2014

I get 10.5mpg towing the gooseneck trailer that's 8k pounds empty. I would check fuel filters,oil,possibly weak ficm or even weak injectors. Check for boost leaks and loose clamps. The 33s are about the same as factory on size. How long do you let it warm up everyday. And idle for because 6.0s eat more fuel at idle then my 7.3s or duramax.

Jeremyleggett07 · Mar 30, 2014

Sounds about right on fuel mileage

60powerplant · Mar 30, 2014

I had a truck I was working on and the guy was complaining about the same thing bad mpg. So I egr deleted and put a muffler back in the exhaust and it picked up 3mpg. My truck seemed to do better mpg with a muffler in then straight piped. So that's why I tryed it on this guys truck.

Powerstroke214 · Mar 30, 2014

Jeremyleggett07 said:
Sounds about right on fuel mileage

WHS…my last tank was 12.5, mostly because I cruised down an old 2 lane at 55 for like 40 mi. It's a heavy ass truck, stopping and going sucks.

My top mpg tip: Drive between 12pm and 5am, when no one is on the roads, and you can hopefully catch all green lights.

Krgillum0 · Mar 31, 2014

I dont let it idle much anymore because i loose as much fuel while idling in the morning as i do driving the damn thing about 15 miles! lol Planning on deleting it once the warrenty the dealership gave me runs out

barnzee07 · Mar 31, 2014

I was havin same issues.ran a bottle of trans fluild thru mine drove about 300 miles one way.after 150 miles it jumped to 15 miles per gal...now it stays around 13.5 to 15.6 also im runnin 35 tires mrp exhaust 6 gun tuner

acf6 · Mar 31, 2014

i wouldn't say thats right. i have a CCLB on 35s and i get 13-15 city and 16-18 hwy

baderic03 · Mar 31, 2014

Every truck is different along with every motor. No 10 trucks are alike. Everyone will be different I have seen.

Powerstroke214 · Mar 31, 2014

acf6 said:
i wouldn't say thats right. i have a CCLB on 35s and i get 13-15 city and 16-18 hwy

The *** do you get 13 city!?

I do have a bad injector though…

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acf6 · Mar 31, 2014

I rarely get below 14 unless it's over the winter. Summer my average was high 14s

Jeremyleggett07 · Apr 1, 2014

From my understanding it all depends on tire size...4x4 or 2wd and of course driving behavior

CoastalF350 · Apr 1, 2014

I have a 4x4 CCLB with a 4in lift and 35s by 12.5. I get about 11mpg at the fill up. I also let my truck idle till it reaches 130 degrees

baderic03 · Apr 1, 2014

Dam my trucks all get 15+ mpg not hooked to a trailer and when hooked to trailers they all get 10-10.5mpg hauling at 70mph up and down the east coast and trailer always has horses in it so it's weight is from 10-18k pounds depending on what trailer. And all trucks tow on a decent size tune. 6.0 is on a hot street tune,7.3 hauls on 490rwhp tune,6.6 duramax tunes in the mid 400s rwhp from other trucks Dyno with similar tunes. I would say egr delete the truck and run some revex in it.

sootie · Apr 1, 2014

OP: you are down on mileage. egr deleted? cold air intake? tire size is no issue-we have one set up identically, 4x4 and 13-14 city with 10-12 mins warm up time before every drive is what we do. running a custom tune from gearhead, we can see up to 18 on an all hwy run.

Powerstroke214 · Apr 1, 2014

How slow do y'all drive!? I don't floor it at every light, but I do keep up w/ traffic, and the best I've seen is 12.9 strictly city, and 13.7 when I made a couple trips to the country. Rpms usually hit 20-2200 and if the speed limit is 50+ then I let it shift into 5th(or 6th if you wanna be technical) w/ the converter locked. Then I usually cruise at 1250-1500rpms. My mom's 4x4 ecoboost got high 12s with her driving…

I'm thinking my city just sucks for traffic.

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