mpg puttin' me in poor house

[rpbfixit]

I need advice. i have hand calc. the mpg for the last 4 tanks of fuel in my 08 sdd 250 and my average is 8.7!! i fill up at the same shell station and do not drive like a race car driver. have a superchips cortex tuner installed and tuned to the mileage XS setting. Have'nt been towing and really making an effort to not let the turbo boost go past 10. fuel filter changed with last oil change (1800 mi. ago) does anyone have advice on what i should check? this can't be normal. i would actually pay someone for advice but i think I'm gonna have to get a second mortgage to pay for diesel. thanks

 

[superduty6.4]

I'm not familiar with that tuner but with my h&s I get the best mileage on the highest setting as long as I don't drive it like I stole it. Last tank that I figured out was 16.5mpg. About 85% highway and 15% town with a fair but of idling in between.

 

[rpbfixit]

highest setting meaning most power/torque?

 

[superduty6.4]

correct, I run mine on the hd300 tuning with the hot setting ( 300hp ). Like I said though I don't drive it like a maniac but it sure is to nice to have some extra power when you need it. For towing I dial it down to the no power ( 50hp ) or mild ( 125hp ) settings.

 

[Dogman]

rpbfixit have you taken it out for a drive it like you stoled it run. I have to do that once a week just to blow the crap out of it. Also the dealership did a update sometime back on mine. said it was for mileage update. It ran like crap for a week or so then started to get better. Get some cetane too and add it to you fuel. I do this on most every tank and seams to help. I get about 11 to 12 mpg city and 15 to 16 hwy running 65 to 68 mph. One thing is if you get a chance when your cleaning mode kicks in get it out on the big road and run it till you hear the cleaning mode shut down. I run in tow mode and that seams to help speed it up the motor runs at a higher RPM.

 

[rpbfixit]

thanks dogman. i'm goin'for a drive!

 

[Dogman]

I have a beat run for tomorrow with a 12K trailer. My truck has been jumping in to clean mode to many times this week so it going to get a work out. Then next friday it getting another about a 400 mile beat run.

 

[superduty6.4]

thanks dogman. i'm goin'for a drive!

So you still have the dpf installed rpbfixit?

 

[rpbfixit]

yes, the dpf is still there. i already know what you're gonna say...get rid of it!

 

[superduty6.4]

No, I'm not one of the guys that preaches to get rid of it. I know everyone ha their reasons for deleting or not. But since you do still have it my idea of running the hottest tunes would do you no good in fact it would probably make it worse because your vehicle would probably regen more often.