Detroit 14L Mileage

14L Detroit is not the best for mileage. What is the transmission, and what rears and tire size do you have? Also, certain lug type tires will decrease mpg almost 1 mpg. Open shoulder tires with low air pressure will greatly decrease mpg. Is he doing progressive shifting, running within the power band by experiementing with different speeds, stopping and starting easy? There are lots of things that affect fuel mileage such as fuel filter and air filter dirty, and keeping all the tires aired up, and don't drive like Mario.

You could very well have something wrong. but you could have a driver problem too. Relations or not, driving easy and steady will have as much of an impact as anything else.

 

if you turn off the egr you'll gain pretty close to a mpg

 

From the folks that I have seen do that, you are right. Most are experiencing substantial mpg gains after deleting the EGR on a 14L.

 

Hey, my name is Frank and I just joined the forum, I own a 2006 columbia with 856000 miles on a 14L and 3.70 rears 10spd. The best mileage I've gotten out of mine which no one here will believe is 7.6 with the ECM reprogammed, without was 7.3mpg. I've got a turbo 3000, aircell and a k&n airfilter in mine and also use meaner power kleaner in it from time to time. I'm also anal on how I take care of my truck, frequently changing the fuel filter every 10,000 miles and oil changes every 15000. Also if you don't already do it, learn how shift at low RPMs on the low side and nothing above 1800 on the high side. Hope this helps

 

What kind of reprgramming have you done ? I have done a full delete on mine and finally getting milage that is good for what i do . I have tried the turbo 3000 and air cell but they in my scrap bin to be recycled now ha ha!

 

I had a friend of mine reprogram the ECM with 600rwhp and about 1950ftlbs with the EGR shut off not deleted completely, so for now I can still use the VGT turbo. Also had an overhead done and new injectors(all 6) including cups and harness. I've had good luck with my add ons, also forgot to mention that I also have a straight thru muffler. My mileage has come down a bit once the computer caught up, but I am still seeing around 7.

 

Oh ok that's good if you don't have a bypass filter it is a good investment for cleaning it up on the inside !

 

Bypass filter? Are you talking about the FASS system or the oil bypass? FASS system is on the list of goodies to get, just waiting to get her paid in full before dropping the bomb on her. 10 more to go whew hew

 

I ment a oil bypass filter i have a spinner ii on mine soot used to be 3.7 and is .7 now in my oil samples .

 

How long have you had it?

And what's a service kit cost?

Did you extend your oil change intervals at all because of this?