Compression Ignition Addict
Join Date: Jul 2010
Location: Falls Chruch
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We are very aware that something is going on.
It is: Those who report the same issue of around 12mpgs seem to be automatic 4x4s. Manuals and 4x2 do not have the problem.
Transmission. I'm on my second as of 4 months ago and no change. As others who use the 44 have no problem, it eliminates the transmission as a potential.
Driving habits: Mileage difference between driving hard vs granny is MAYBE 1 mpg difference and that could easily be explained by not filling the tank all the way at refuel.
Winter fuel: Problems there in the summer, winter fuel knocks a bit off as it does for everyone.
Fuel pressure/blocked lines/filters: I just went through replacing everything on fuel delivery. I have perfect pressure and no issues. Mileage is still crappy
Up Pipes: Replaced. No change in mileage
Boost leaks: Have none. Fully inspected with a boost leak detector
I have NO codes
I have NO hanging calipers
Things that dont help:
I have some beefy tires. Let me rephrase, i regret purchasing big beefy tires. They are loud and reduced mileage instantly. I've compensated my mileage expectations and even adjusted, i find my truck is low on MPGs
The Tuner - I have the same one as you - Super Chip or whatever they call the silly thing. It makes a large difference with the truck - no question about it but it does NOT increase fuel mileage. It decreases it if anything. I get better in stock tune. There is no tuner out there that increases fuel mileage. I repeat - NO tune will increase mpgs. (There are some really informative posts about the aerodynamics of the 7.3l trucks and ways to get 20+ mpg. Tuner packs were tested and none increased mileage over stock. The research is there on this one - please spend some time reading)
I have a sneaky suspicion that 4" turbo back exhausts and TYMAR intakes also decrease mileage. This one usually causes a riot though
on the forums
At this point im leaning towards bad o-rings on injectors. I'm saving some cash for a stage 1 swap and i will see if it increases mileage more than the normal 1-2 mpgs.
Nonconformist. Functionality over bling.
My three rules for 7.3l troubleshooting: 1) Replace CPS and keep a spare. 2) Replace FPR and know your fuel pressure. 3) Hook it to a scanner and check for codes.
Last edited by audiocontr; 01-16-2012 at 07:22 AM.