So I recently purchased a 94 dakota with a 5.2 5spd 4x4 ex-cab. truck is super clean and was meticulously maintained by po who was original owner always has had mobil one in it. the truck has 130k and it gets terrible mileage. It does have 31x10.50's on it truck seems to run good although she seems a little short on power which is wierd for the 5.2. It has new plugs wires cap rotor, thermostat, ect... I plug it in every night(dual block heaters) and drive it very conservatively, and about 90% highway everywhere i go is at least 55 mph to get there all open road.

My mileage has been consistantly 15mpg which i feel should be higher and the last tank it was 13. I have ran 2 tanks of sea foam thru it.

This isn't my first experience with a dodge I had a fullsize 96 on 33's with a 5.2 auto and it used to pull 17ish around town and would burn the tires readily. My dad is on his second durango which also has great power and mileage in the 19-20 range. Any help would be greatly appriciated.

BTW no CEL's or miss or anything.

thanks.

 

I have a 95 5.2 and have just put my first tank through with new 31x10.5's and got about 13 mpgs. Was getting about 15 as it was before. I think thats about all you are going to get. I can get about 230-250 miles per tank.

 

THAT DOESN'T EXPLAIN WHY A RAM WITH 33'S 3.55 GEARS AND A 5.2 AUTO GOT ME 17ISH IN TOWN.
and my dads 5.2 rango used to pull him consistant 18-19 mpg's. and rangos are heavier than daks.
AND OTHERS ARE CLAIMING FAR BETTER MILEAGE AND POWER ON HERE THAN THAT WITH 5.2'S. JUST TRYING TO GET SOME IDEAS. (oh and not yelling just had caps on) sorry. lol. didn't wanna retype.

 

If you figure out how to make it better, I will certainly follow along!

 

yeah I have read on here that several people see improvements after changing the O2 sensor which I haven't done. I know on my bronco I saw some gains after bumping timing 2-3* and gapping the plugs wider. idk tho might try some things. cuz I bought the dak cuz i wanted another dodge and didn't want the mileage of a fullsize, but kinda wishing I'd of bought the fullsize right now cuz I coulda got a quad cab lol. not that I don't like my dak cuz I do just wanna see some gains.

 

I have heard about the 02 sensor too. That would be an easy swap. I dont think you can mess with the timing on the 5.2. Im pretty sure thats controlled by the computer.

 

Yeah and it aint too expensive at the parts store i work at like $29 or so. The timing on the fords is ecm controlled too but you can still bump it. you may be correct on the 5.2's tho.

 

Then your Ram was a freak, because that's unheard of.

I was averaging 15.7 all summer doing 70% freeway, I've dropped a full MPG now that we have winter gas. It doesn't take much town driving to drop MPG a lot, I can do 18.5MPG 100% freeway, if I do much town it drops pretty fast. Your bigger tires also cause your odo to read low.

Fix the plenum and replace the O2 sensor.

 

fix the plenum? And does that make my dads bone stock durango a freak too? it used to pull 18 religiously. Also I have a shell on my truck not that that matters much.

I was planning on replacing the 02 sensor more info on the plenum fix would be great.

also my speedo is dead on at 45 mph and im doing 62 when it says 60 so it isn't off that much that's according to a gps which may not be entirely accurate. same up to 80 too btw which i rarely drive that speed.

 

Every single one of the cars I've tested with a GPS are exactly 2 mph under what's shown on the speedometer, so I figure that must be a standard amount of fudge factor thrown in by the factories.

My 1995 Dakota sport 2wd with a 5.2 gets 18mpg consistently with stock tires and wheels. That's actually a mix of highway and local since I'm in a rural area. You tend to do both going anywhere. Pure highway has actually hit 20mpg twice. Nothing special has been done to it, and it's got so much rust that you would think the drag alone would be cutting down the mileage.