First off I would like to thank the guys who helped me find the MAP sensor in the "what does the map sensor do" thread.

I took off the map sensor line and found that it was not clogged, is it possible that the MAP sensor could go bad and me not have any major problems?

My concern is that my truck only gets 11-13 mpg (unloaded, 4:10's), even on the highway. I've been keeping track of my fuel mielage (by hand) since I've got my truck in July of 2006. I know alot of you guys have been claiming that you can get 15-20 mpgs, but I cant even touch 14. I'm Here's a list of things I've done to try to find my problem/ improve mielage:

Always keep it under 2000 RPM
Keep the tires aired up to spec.
Run a fuel additive (Diesel Kleen, just switched to Stanadyne)
Change the oil every 3-4K (with filter) Mobil 1 Delvac
Usually replace the fuel filter every oil change
Try to let the truck warm up completely before driving
I run Hess fuel (tried fill-ups with Citco and Shell, no better mpgs)
I used the cap for 2 months to try to improve wind resistance (just made my truck look silly)
Use cruise control as much as possible
Replaced the FPR screen
Checked MAP hose for clogs
No CEL's

I know it sounds like I'm complaining, its just that there has got to be something wrong. I have 5 close friends that all have OBS powerstrokes and all of them are getting in the 15-20 range aswell. I would think that with my superchip tuner (tow-safe) a downpipe/exhaust, and a cold air intake, I could be doing a little bet better than I am.

Am I missing something?


As always, thanks for your imputs in advance.
-Brian

 

Don't let it warm up very long. Just give it a short time for oil to flow, use the block heater if its too sluggish in cold and give that a go. Not gonna help much in the summer but it will help some.

Also how many miles on the truck? any injector work been done. Could be injectors getting weak or carboned up nozzles not creating a clean spray pattern any more.

 

its got 141K on it.. i have not done any injector work since i had it, and i got it from a dealer so im not sure if the p/o did, but i doubt it. i though maybe my injector o-rings could be bad, cause it looked like i may have had some oil bubbles in the fuel filter, would that be a sign? the truck really does not smoke much, just a little bit of white when i start it in the cold. is there any way i would be able to get rid of carbon build up on the nozzles?

 

I agree with TJ. I used to warm-up my truck awhile before driving (see my sig for truck info) and could only get 15 MPG at best. I started using Diesel Kleen, did the FPR Shim and cleaned the screen, and did the 6637 mod. With the DK, the first tanks were shocked (doubled the normal dose) and then used the recommended amount.

Like you, I try to keep her as close to 2000 RPMs as much as possible, and with 4.10s, that ain't often. I'm consistently getting combined city/highway unloaded mileage of 17.25 MPG, and I do have a camper shell on my rig. Silly-looking or not, I think it helps a little bit.

My commute is fairly flat, so I don't use cruise control all that much. If you're in an even slightly-hilly area, it's better to use your foot instead of the button. You can ADJUST to the up-down sooner than the cruise control can REACT to them.

 

o-rings are a possibility, mine were so bad that the truck wouldnt even get up and go to merge into trafiic and my mpg only dropped 1 or 2 points.... is the fuel filter black and grungy looking when you change it?

you basicly have the exact same truck as i do with the same mods. the only other things i have is the 14.7k icp, intercooler, and 4.7k oil temp. i have 4.10 gears running 315/75/16's. the intercooler made 0 difference in power or economy, and the 14.7 was only a power adder, no raise or drop in mileage either. the 315 tires with 4.10's make my truck ride as though it was on stock tires and 3.55 gears.
the oil temp mod is a new addition and i just got done my first set of tanks with testing and that will be in another post...lol but aside from the oil temp mod i always got 16.8-17.3 mpg this time of year. once the temps warm up i usually run 18-19 and change in the summertime. this is unloaded miles and my trips are 100 miles a day from work to home, probably 10 miles of under 30 mph, 15 miles of 50-60 mph, and 25 miles of 75-85 mph.

 

Don't foreget the stops that you make to pick up everything that falls out the back of your truck.

 

fuel filter is pretty clean when i change it, and the truck will still get up and go when i need to. also my oil level does not really change, thats why i think its safe to rule the o-rings out. your truck being virtually the same as mine is what gives me the idea somethings up. i used to have 35's, and now im down on 33's but my numbers havent changed too much. regardless, i think i should be getting closer numbers to you.

moose man, im gonna keep that cruise control tip in mind. maybe if I give it a shock of DK next fill up maybe ill try shocking it like you did to possibly clean out some of the carbon build up i could potentially have