My D is supposed to get 12 mpg. My computer shows im getting around 9mpg around town(all short trips). When i go to work(20 minute drive on highway), I'm getting about 11mpg. I've got new spark plugs and a k@n air filter.Tire pressure is where it should be. Any suggestions to how i can improve my fuel mileage?

 

keep your foot off the floor, worked for me,

you could try using cruise control where ever possible and if you toe the speed limit you dont have to brake as often, hence wasting less energy (gas)

you could also change your front(pre-cat) o2 sensor that might help some

 

My computer readout shows me doing around 8.2-8.7 just driving in the residential area. At first, I said no freaking way! My engine is running in top shape. Whole D is running in top shape. I went to fill up my tank when it was sitting at 3/4 to see what my mileage really was. burned 4.7 gallons but driven 60 miles. This translates to 12.7 mpg just driving around my neighborhood. Damn worst calibration I seen from my computer console. usually it is about 2 mpg off target for local stop and go driving. But to be 4 mpg off target, that sux. But highway driving, the computer is within 1 mpg of my manual math calculations.

I cannot wait until the HHO thread is done so I can start getting it setup on my rig!

 

MyD is an 02 SLT 5.9/3.92 4x4 with 77k all stock except for a K&N filter. It was rated at 12/16 when new and I get 11/15. Seems the 2 major things for me is keeping it tuned (including keeping all fluids fresh) and driving like there's stick pins in the pedal and I'm barefoot. I do use cruise whenever possible. On the highway 70 mph seems like the sweet spot for me. Tire pressure affects mpg's very little as long you run the pressure in the rangethe tire was designed for. If I'm going to tow, I bump the pressure in the back up a few pounds, Keeping good tread and good alignment probably helps more than pressure does. I do agree with keeping the O2 sensors fresh, their performance degrades over time even though they still function. It's one of the major things the computer uses for correct fuel/air mixture.

 

Jeff, I concurr about the 70 MPH. Seems to be a good cruising speed for speed, distance, and MPG. I have been known over a trip to get up to about 18 with moderate loading, A/C on Cruise set and full electrical load, radio, lights, etc... I read the part about replacing 02 sensors, which ones, if I recall correctly there are four. Are we talking the before CAT sensors, aft of cat or both? Does anything have to be reset for this or is it just replace, plug and play?

 

The before cat sensors are the ones the computer uses for setting fuel/air mixture, the after cat sensors are just used for comparison so the computer knows the cat is operating correctly.

 

03:

My console computer sometimes says I am getting 40mpg!!! I have never seen one in a vehicle that was worth a plug nickel. The window sticker for mine says 13/18, and IIRC the 5.9 engine is rated as 12/17. I have found that they were pretty on the spot, as I run 12-13 around town, and 17-18 highway. A couple of times with a good tail wind and holding my mouth right down hills I touched 19.

Almost 5000 pounds and the aerodynamics of a brick are key factors in our Durangos thirst forpetrol.

Don

 

Jeff, if you are still logged on. Will there be a reset of the computer or any emissions work to do after replacing the sensors or are they plug and play and will set the fuel/air mixture with the new unclogged sensor. Will I get any M.I.L? Or better yet should I,? N8ech you might want to weigh in on this one.

 

Should be plug and play. Unless you had a problem before replacement.

 

never had a reason to replace the ones on the D but i've had to replaceall of them on the jeeps because of milage, 135k and 180k on them.