I have a 2000 dodge 1500 van and getting about 11 mpg city and 12 hwy mpg. It has been tuned. My brother has a 1996, same engine (318) and gets 3 to 4 mpg better. The vans are practically the same, tires, milage etc. The owners manuel says it should be about the same as his. Can someone relate to this? Thanks John

 

is your overdrive working?
what else? O2 sensor, bad cat, faulty injector?

 

No trouble codes come up and yes the overdrive works. the van runs good .It had 47000 when I bought a year ago, it now has 62000 Thanks John

 

How does it run? Any hesitation/stuttering at all? Different gear ratios will do it too.

 

How is the vehicle driven? cruise around town, stop light to stop light, or mostly highway?
I have a 93 dakota 4wd with the 5.2 (318) in it with 205k original miles on it--still gets 15 mpg highway.
Its possible the thing is carboned up--when they tuned it up, were the plugs light grey or more black?
One of the first signs of a catalytic converter plugging up is loss of power, poor gas mileage, and sometimes a loud wooshing sound from the exhaust. Sometimes it can be jst simple vacuum lines leaking too. The the engine bay for any loose hoses, or funny whistling sounds. How much weight are you carrying compared to the other van? If you have a lot, such as a service van situation, it might be better to drive in 3rd gear instead of overdrive--hope this helps--just some suggestions BEFORE you take into the guy with the scanner

 

I'd say the van is driven about 1/2 and 1/2 city and hwy. The plugs were clean when changed. The exhaust smells normal. The engine is smooth. The only thing I notice ,when the engine is cold the idle varies for awhile but no codes are present. I do suspect the IAC but wonder if that would affect gas milage. Thanks John

 

change oxygen sensors. theyre only going to go about 60k.

 

I agree. The o2 could very well be the problem.

 

the 02 sensor makes that big of a difference? maybe thats what im only getting 11.9 w/ my truck. i have 66000 miles on it.

 

With the price of gas that's a cheap fix. I'll give it a shot. Thanks John