dodge durango, bad gas mileage.

viridionplague · 12-31-2009

just thought i would share this with everyone. i recently bought a 99 dodge durango for winter commuting and a few other things. its got 147k on the clock, with an auto trans, 318 engine, switchable 4 by.

runs very nice, no stutter or hesitation. just a little hard to start when its warm, but easy when its cold.

been getting some very bad gas mileage, and ive been around on some durango boards. this is my most recent post, and you should get the jist of it. any help anyone can offer would be appreciated.

**i replaced the cap, rotor, and sensor, spark plugs, replaced and re checked all fluids and air filter.

was still getting bad gas mileage. took it to a shop, they put 8 hours into diagnostics and still didnt find anything wrong. only paid for a half an hour though.

filled up the tank, drove 4 miles. the tank took 1.5 gallons to fill up.

thats right...4 miles...1.5 gallons. 2.6 mpg. there are no fuel leaks, engine runs good, and has plenty of power.

i am at a complete loss as to what i should do next.

any ideas as where to look next would be much appreciated, as the shop would also like to know whats up with it.**

s1ngletracker · 12-31-2009

does the exhaust smell really rich? I mean, this thing should by all rights be pouring out black smoke when you're driving down the road. Did they check to see if the injectors were stuck open?

viridionplague · 12-31-2009

exhaust smells fairly normal, i have not actualy pulled the injectors to check them.

NOT THE BLUE LAMPSHADE · 12-31-2009

Do you know if there we're any stored codes from the computer? Is the check engine light on? If there are no codes, then maybe somethings up with your fuel pressure regulator bumping the pressure way up but not triggering the computer? But this would lead to black smoke and/or the exhaust smelling really rich. Perhaps something's up with an injector, maybe leaking, multiple injectors leaking possibly. This is an odd problem...

viridionplague · 12-31-2009

only had one code pop up, that was a downstream 02 sensor, i dont think that would cause anything.

i was thinking maybe something with the regulator as well, maybe there to much pressure and its pushing its way through the injectors, but somehow dosent cause it to run like shit. its very odd

**goodhart** · 12-31-2009

I bet it's the 02 sensor. My Dad's old 99 Ram had one go to shit on him and all of the sudden he was getting 2-3 mpg. My money is on the 02 sensor.

1QUICK4 · 12-31-2009

Quote:

Originally Posted by s1ngletracker

Did they check to see if the injectors were stuck open?

+1

Very common for those Durango's to have injector issues

Quote:

Originally Posted by goodhart

I bet it's the 02 sensor. My Dad's old 99 Ram had one go to shit on him and all of the sudden he was getting 2-3 mpg. My money is on the 02 sensor.

The downstream sensor is only there to monitor that the cat is doing it's job. Only the upstream sensors should have bearing on the fuel mixture

Andrew7dg · 12-31-2009

I mean do you see the gas gauge physically going down!
Wow I mean if it were THAT bad of gas milage something else should be showing signs I would think

leaky tank? any leaks? sometime it is hard to see this in the snow...

I thought my truck was getting worse then normal gas milage... checked on the Forums... NOPE that what it gets for normal gas milage...

s1ngletracker · 12-31-2009

I'd also be really careful, have you smelled your oil? If you're running that rich, you're probably also washing your cylinders and getting gas in your oil, breaking it down. I'd stop driving the truck till you figure it out (you probably have already) Somehow I just have a hard time believing that you don't have a leak. I dont think your truck would run fine if it was getting 2 mpg.

viridionplague · 12-31-2009

shop checked the system for leaks, they let it sit inside overnight so all the snow melted off first.

its common for these trucks to get around 12 mpg, so its not as big of a drop, as if it was a car getting 20 or better.

i stopped driving it a long time ago, i havent had the money to do any repairs untill recently.

it is still pulling good vacuum and everything it makes no sense for it to be getting as bad mpg as it is. but i will happily take someone for a 5 minute drive and still put 2 gallons in the tank when its over.