98 explorer horrible gas mpg

[RangerFabWorks]

i got a 98 explorer 4 door with the 4.0 sohc and 5r55e trans. i just did plugs, wires, air filter, seafoam, all the fluids, and new tires on it less than 10k ago. it has 140,000 on it.

im averaging 12-14 around town, some may say thats normal, but i baby the piss out of this thing. i think it should get 15-18 around town. best i ever got was 18 on the hyway driving down south.

would my o2 sensors cause this? and would they mess my cat up, because its been like this for the 10k ive owned it for.

i used synthetic oil in everything, and i bought the best plugs and wires i could buy and have everything set to factory specs.

thanks in advance.

 

[trader007]

i would get a detailed scan of your pcm's to see if there are any sensors out of whack. not all bad sensors will throw an engine trouble light.

if nothing has really been replaced though, then o2 sensors probably are close to going bad anyway... also clean your MAF sensor, that usually helps a lot. clean your pcv valve too.

 

[Jason]

That's all my Ranger got with the same driveline more or less. From day 1/

 

[RangerFabWorks]

ok, so i dont have a light on, but i had autozone scan it for craps and giggles, ands its showing a code for the o2 sensors.

so i know there not helping anything, but will they increase my gas mileage to where it should be?

on my blazer, i replaced and my gas mpg stayed the saame. and they were so bad you could only run certain gas in it.

but, im not sure if this is related or not. sometimes when i start the truck, the idle bounces for a few seconds, then evens out. almost like it doesnt know to raise the idle for a cold start.

and, the truck idles, and drives fine. but iof you bring the rpms up to 1700 it surges slightly.

just adding some clues to the puzzle.

 

[RangerFabWorks]

That's all my Ranger got with the same driveline more or less. From day 1/

wierd, but a 6 cylinder should get better mileage than this. i only have 3:55 gears and never go above 60, and baby the gas.

if it dont get better, im selling this and getting a v8 pickup. if im gonna pay this much in gas for a 6 (i shoulda had a v8)

 

[hondaxr650]

I know lots of people unhappy with the gas mileage on their Explorers and Rangers but that's pretty much normal. I get 15-16 with mine doing combination city/highway driving. Best I ever got out of it was 19 on a long highway trip. My dad regularly gets over 19 with his '06 gmc sierra with a 300+hp 5.3.

 

[Horsepen]

I live in North Georgia in the hills and most of my driving is here around the local area, to Walmart, Publix, Gas station, pickup a few bails of pine straw, maybe run down to Sandy Springs once in a while. So a good combination of highway and secondary roads with some in town mixed in. I've been checking my mileage for quite some time now off and on. I filled up, checked my tire pressure on my stock tires (28 PSI) and had a Magnaflow muffler installed to replace my stock muffler. Left everything else alone underneath. I also added a bottle of Fuel Injector Cleaner when I filled up. I did not let the engine idle for 30 minutes to reset the computer nor did I unhook the positive battery cable for 10 minutes to accomodate the new muffler. I got 286.6 miles on the trip odometer and took 15.778 gallons. This works out to 18.17 mpg. This is the best I ever got with this truck. BTW, it has a limited slip 4.10 ratio differential and the truck is the stretch cab version. I am so proud of my truck's mileage. I'm thinking the new muffler is helping, but don't know how much credit to give it. Any thoughts from anyone?

 

[RangerFabWorks]

WELL, im prob gonna sell it come spring time and get a silverado v8. id rather have a v8 than pay for a v6.

but i WILL have fun in this thing comes first snow fall

 

[Sasquatch_Ryda]

What exactly was the code? That would help a bit to know that.

 

[feellnfroggy]

Our trucks are only rated 18 and 23 respectively from the factory anyways. Most years with 4.0 and 4x4 anyways. Id replace the o2. and maybe even replace the cats using whatever method you feel neccessary. Clogging in the cats is possible, 98 is old enough to have seen some busted emissions parts to cause running rich which will put excess fuel in the cat and clog it up. Also babying hte gas is a good way to lose mileage also. There is a certain range of efficiancy in motors and if you baby them too much causing low shifts points then bogging the motor will actually hurt mileage. If you watch the air/fuel Ratios on carbs the higher in the rpms it goes the leaner it runs. THe same principals apply to the fuel injected motors just not nearly as bad. anything over 2000rpm is an ok shift. Most people dont have a prob with 1500 rpm shifts but some motors are extra picky. I normally shift around 3k unless traffic has me draggin it out too long. wHat size tires do you have? You did all fluids, does this mean(stupid question I know) the rear diff fluid as well? Have you checked your bearings? Tire pressures? what about your a/c is it running efficiently or dragging more than it should? same with the other accessories? anything squealing or slipping? Theres alot that affects mileage. How bout a picture of the bodywork. People say its bogus, but you'd be surprised how a wash and wax will help at highway speeds. LOL. hope this helps

 

[Kalwren]

Just tossing this out there... Have you tried cleaning your MAF?

 

[Mr99Ranger]

My Ranger gets around 10mpg city and 14 highway. Does this summer or winter, rain or shine. this is baceaue of several factors. 1 is i drive the piss out of it, 2 is it has a bad thermostat runs cold all the time, 3 is 4:10 rear gears and i drive 85 on the highway.

 

[RangerFabWorks]

ok, short answer to most of the questions

yes i did the rear diff with synthetic fluid, yes my tires are at 40 psi, yes i cleaned my maf. yes i clean my truck regularly. heres the link for it http://www.therangerstation.com/forums/showthread.php?t=86933

no, when i mean baby, i dont gun it off the line, i dont speed up going up hills, and i dont speed. going up hills, i manually kick it down a gear so the motor doesnt struggle.

it shifts at like 2700 rpm normally.

i think its the o2 sensors, im going to replace them when i get the ranger going so i can lay the truck up for a day or two.

 

[feellnfroggy]

any progress?

 

[RangerFabWorks]

Well. I aired my tires up to 40 psi. I had em all at 30.

I filled up and drive it till empty and got 14.6 mpg doing a mix of highway and city driving.

I'm hoping to replace the o2 sensors and get it up to 20mpg soon as I get the ranger on the road.