fuel milage question

[ropen699]

I have a 2006 f350 6.0 with 66,000 miles on it. I am only getting 11.8 mpg. I do not hot rod my truck around or am pulling a trailer with that 11.8 fuel milage. I have 5 friends that have 6.0 and are getting at a minimum of 15 mpg in town and a high of 21 on the free way. I realize it depends on if you have a lead foot or not. My friend with the lead foot is getting 15 mpg in town and 17 pulling a horse trailer down the free way. she has a 2005 6.0 f250. I just bout this truck three and half weeks ago from a dealer. I was wondering if 11.8 mpg means something is wrong with my motor. The only thing i have seen is a engine light turned on a week ago. It was scanned and it was a turbo under boost. I looked under the hood and the top fuel filter rubber gasket was broke and pouring out fuel. I fixed that and cleared the code. I filled up that tank and reset the odometer and checked fuel milage again and still got 11.8. The engine light has not gone on again. I have stomped on it a few times to get as much boost out of it to see if i could get the engine light to come on again and it has not. Is 11.8 normal? Should i be concerned?

 

[snicklas]

ropen,

A couple of questions.

What gear ratio is the rear?

How are your starts? Normal, long/hard starts.

If you are seeing fuel economy issues and not a high rear ratio, especially if you are having hard starts, the FICM could be failing. There is a test to see if that is the case.....

 

[NJKen]

Youre doing better than me. I have an 06 F550 that will not get any better than 9.5 no matter what I do. It has 5.88 gears and weighs in at 15,000 lbs though.
Ken

 

[cbarm]

Are you figuring out your MPG's by using your dash ecm/dash display? Those are NOT accurate so I wouldnt believe what they say. If you put pen to paper then you will see that it can be off a ways...

 

[Broncoxraptor]

Any add ons? I have EGR delete and turbo back exhaust with no cat and SCT tuner set for street performance. I get those numbers your friends do. 16 towing my bronco at 70 and 20 empty.