3.9 2002 Conv Van - mileage?

Have a friend who picked up an 02 3.9 - no o/d, 3.55 gear, 49K miles. Mileage sucks - like 9 - 13 MPG. I know of earlier similar models with o/d and probably a 2.9 gear that were getting up to 27 mpg. So I'm thinking something is seriously wrong with this thing. Outside of a normal tune up, any things to look for? Or is this typical?

My sister's old '97 with the same drivetrain would get 16 ~ 16.5 hwy MPG running 75 ~ 80. I don't know the city mileage, she never tracked it.

Robert

The lack of the OD trans is going to kill the mpg on the highway. A 3.9 in a conv van probably doesn't have enough power to pull a van around at highway speeds in OD, it can barley pull my standard cab Dakota in OD at 60 mph.
Tht 9-13 is about right for city driving. Gene

27 mpg out of a six cylinder van? No way. Ever! Unless your constant speed in a vacuum was 35 mph.

My 1990 Ram 150 3.9 5 speed got 24 mpg, but that was a different era, probably a lighter vehicle, and the manual transmission doing most of that. Vans of your era got about 16 mpg.

27, maybe going downhill in neutral. Otherwise, no. My parents 2wd, 3.9 auto trans, 95 dakota did upper teens highway MPG at best. If you're pushing a 4000 pound garden shed down the highway with a 3.9 and getting in the teens mpg, that's right in the ball park.

I have never seen higher than a 3.55 gear come with any automatic OD trans, I would like to see a pic of the option sticker for any vehicle that had one. The combo you have is getting just a hair less than I think it should but could easily be the driver, my wife typically gets 1/2 the MPG I do in the same rigs, she gets 9 or so in our B3500 and I get about 18 but it is a 5.9 with OD (I built a 44RE for it as it had no trans when I bought it and I prefer the smaller one) so actual displacement per mile is nearly the same as yours, (360X.69)=248 vs 239 per driveshaft revolution. In general I have found this to be a good baseline predictor of what MPG a vehicle should get. I added a CAI and slotted and advanced the crank sensor to advance it, I got 2 degrees more advance. I also went from the factory 245-75-16 tires to a taller and narrower 235-85-16. I did not do a before test so it just is what it is. I would like to lower it a tad and stick in a 3.21 gear to see what I get. Ours is not a conversion van but a 15 passenger with 1 seat removed, I don't know how that compares weight wise to a conversion van. I think if you are not gonna swap in an OD than a 3.23 or even 2.94 gear would help, not drastically but some for sure, we are not building these for racing (at least I'm not). Also you could add the ford 4.6-5.4 injectors for a tad better MPG, yours being made after 1999 needs a set of cheap e-bay plug adapters to bolt them in.

Didn't know you could get anything in 2002 without an OD...

Or, do you mean its not working?

Either way, my stone stock '93 Dakota gives me a pretty consistent 14MPG in 100% in town driving. The two times I've driven it some distance on the open highway, it gave me in the low 20's.

The OD in my Dak works fine. I turned it off once to see the RPM difference at hwy speed....

Dodge used to build conversion van packages, specifically to be sold to conversion companies. The base V6 non overdrive (32RH) was the basest of all. IIRC, all of them set code 37 because there's no overdrive and no specific non overdrive PCM to compensate. Again if memory serves, they were available as B1500 and B2500's.

Robert