I know the heading is kind of a oxymoron with the D but even with I am getting extremely poor fuel mileage. Here is what going on and some recent maintenance.

I used to get about 350 miles to a tank, I even stretched out to 400+ miles a tank on a Pittsburgh-Indianapolis trip. Yes highway with A/C on cruising about 70.

Lately I can not even get 300 miles to a tank. When I fill tank after fill and before start, trip computer indicates about 290. Used to indicate about 370.

I understand city driving, stop and go, etc........... but it seems poor even for a durango.

Recent work. Mileage in parenthesis

Spark Plugs DEC07 approx 7(6200) replaced with Champion Copper. (X8)

Transmission REBUILD JAN 08 (77000)

RH CV DRIVE AXLE JUL 08 (87450)

FRT BRAKE PADS JUL08 (87600)

PCV VALVE AUG 08 (87900)

ALIGNMENT/BRAKE FLUID FLUSH R/R BRAKE BLEED (88300)

FAN BLOWER MOTOR RESISTOR AND WIRING HARNESS OCT08 (90400)

ALIGNMENT DEC08 (96000)

AIR FILTER FEB09 (99200)

WATER PUMP AND SERPENTINE BELT MAR09 (101K)


STATE OF VIRGINIA SAFETY/EMISSIONS INSPECTION. Replace fuel cap APR09 (101700)

OIL CHANGE/FILTER (102.1K)

SHOCKS (X4) PENDING (AWAITING SHOCKS FROM FEDEX) EXPECT THIS WEEK OR EARLY MAY.

I used to be able to average about 15-16 in town, currently only about 11-12 MPG


Any suggestions? I am thinking the PRECAT 02 sensors, to start with, but beyond that any ideas?

Steve

 

You're in the same boat as me. I used to get 12-13 in town, but now get 9-10! my R/T runs rock solid. Only thing is that I only drive it part time if that much. All sensors have been replaced since I owned this R/T except for the 02 sensors. As my truck is approaching 90k miles, I think it is time to replace all the 02 sensors. no use changing one if the other may be on the way out soon. I will have it change sometime next weekend and then take it out for a drive to see if it improves my mpg.

 

OOPS!!! Almost forgot 03 SLT 4X4 4.7 still factory air filter.

 

Damn Magic, you still have factor air filter? You talking about the original oem filter that came with that 03? that may be your problem then! haha

replace it with a oem K&N replacement like I did. you'll even notice almost a 1 mpg improvement for a good filter that lets your engine breathe.

 

290-310 on milage here, always.

Fuel quality changes. We are leaving winter blends now and going to (worse) summer blends. Could be a factor.

O2 sensors could be due for replacement. Could be a factor.

IAT and other TB sensors could be cleaned/replaced. Could be a factor.

TB itself could be cleaned. Could be a factor.

Air filter could be cleaned/replaced. Could be a factor.

That's about it.

I would die of shock to get 350-400 miles per tank.

IndyDurango ---> Full Time 4x4 5.9L

 

i can get 350-400 per tank all highway, but then i have the small 4.7 and part time 4x4

 

"Damn Magic, you still have factor air filter? You talking about the original oem filter that came with that 03? that may be your problem then! haha"


Let me clarify, Not Factory air filter, but still factory set up, I mean no CAI kit, I replaced the air filter in FEB09

Throttle body housing and IACV were cleaned about two weeks ago.

I forgot about the fuel blend change, that is a good point. Sounds like we are off to a good starting point. I will start with filter again, and then O2 sensors, I wanted to run by everyone to make sure there wasn't something I was missing. Thanks!!

 

I was using the stock air setup, recently bought a cheap eBay intake, removed the rubber flap on the right front by the radiator. Computer now shows I'm getting around 19-20mpg at 70mph (highway) compared to the 16 I was getting. (haven't finished the entire tank yet to give actual math numbers)

You could switch over to a home made system with a K&N drop in like a few people have here, however I think the air hat is the biggest problem with the stock setup.

Ever ran Seafoam through the fuel system? Seemed to help me quite a bit when I 1st bought mine, got me from 14-15mpg to 16 at highway speeds.

 

Yeah, I just seafoamed my cars yesterday... LOL! There was hardly ANY wind movement at all... I got a mile and a half down the road and the smoke was STILL sitting there... It was the strongest I have seen it too... Got to the store, came back and it was still hanging around, just no where NEAR as bad as it was earlier... But I did notice so far, the Durango revs higher, faster and is MUCH smoother... I'll see what it does for mileage... I don't think it will do anything... But then again, changing all fluids got me about 3MPG...

 

Have a back pressure test done on your CAT. You should run under 3psi. A muffler shop can do this for you and is usually free of charge.

Do a CIA and K&N or HI Flow dry filter.

Transmission filter/fluid might need changed.


Does it run hotter than usual?


Also, Never trust the overhead unit! Always check your actual numbers at the pump.