MTL_4runner

Hmmmm.....Jeff, that may be part of the issue. Were they the OEM Denso O2 sensors? If you don't use OEM sensors you can cause all sorts of issues like CELs, bad gas mileage, etc. FYI Gadget over at URD has some of the best pricing on OEM sensors www.urdusa.com cheaper than sparkplugs.com for sure. Do you still have the original O2 sensors so you can try putting the old ones back in and checking if that was part of the issue at all? The other thing I would try is to use another set of stock dual electrode plugs. I would try and eliminate the posibility that it was either of those before I jumped to the conclusion that it was something else causing the bad gas mileage. Also make sure you pull the negative battery terminal for a minute to reset the ECU.

Jim McNabb

Don't know if you all have the same problems with fuel that we do out west, but they oxygenate our fuel from Oct. thru Mar. by adding ethanol. My mileage always drops a bit when this happems. I have a cou;le of friends who have newer vehicles that will run on that stuff & they both report lousy fuel mileage. Try adding Marvel Mystery Oil to the fuel @ 1 oz per gallon, it helps, don't know why. It's a Mystery !!!!

jrallan26

Kinda / sorta on topic:

After a tuneup and disconnect the negative battery terminal to reset the computer. My question is: Do you have to reprogram your keyless entry?

BMWToyotaMan

I am still getting 14-15mpg with a combo of city/highway driving. I think the 4runner has a slight exhaust leak but I wouldnt think it would cause any problems with gas mileage.

Jeff

mkgarrison5

i just did the seafoam. one can to the intake and 2 in the gas tank, changed plugs, fuel filter, front, rear and tcase gear oil, and motor oil changed and i havent seen squat difference in gas mileage... it runs a lil smoother but thats it.. and yes i had the negative wire pulled from the battery until every thing was done

BMWToyotaMan

what kind of gas mileage are you getting?

Beartracker

Only 2 other things I can think of or maybe 3. Try a new fuel filter, have the injectors pulled and cleaned and try a different gas.
The winter gas plays hell on my 2.7. I go down at least 3 miles per gallon in the winter. It's like I can watch the needle go right to empty in the winter.
I go to 17-18 mpg from 21-22 and that's driving these mountains every day.
Mike

BMWToyotaMan

I have begun to think its the time of year with the gas grades, I have already replaced the fuel filter.

15mpg is really bad for a 6 cylinder, maybe I should just buy a turbo diesel and get 16mpg while towing 8,000 pounds.

MTL_4runner

Really cold weather like we've been having can really cause havoc on your gas mileage because the air is much more dense and the gas has incresing amounts of additives like alcohol and other oxygenators. Mine can go as low as 13-15 MPG in the dead of winter while city driving and highway might be more like 17-18 MPG. Even the new hybrid gas miser cars can take big hits on gas mileage (sometimes as much as 25% less) from very cold weather.

BMWToyotaMan

yea that makes sense up there but in Virginia Beach the lowest it got was mid 20s. I am going to replace the brake pads, maybe that will give me better gas mileage.

Jeff

fotorunner

Running down the road, no wind, properly inflated tires, not heavily loaded, on fairly level terrain for 200 miles at a stretch my 98 and my 97 T4R usually got about 19 to 21 mpg. The best I ever did was in my 95 Runner from Denver to my home and that was 23 mpg.

Last May I replaced the plugs and wires in my 97 T4R, it was well past time and I’d developed a bad miss because of crappy wires. After doing that work my mileage actually dropped 1 to 2 mpg (I logged the mileage every fillup) I was getting about 17mpg on a combination of around town and some in county driving with a little bit of 4 wheel drive stuff thrown in. All in all I thought that was acceptable. On the road it was running 18 to 19 mpg where before the plug replacement I was getting 20 to 21.

So far this winter my mileage has sucked. But since December the weather has been cold (under 20 most of the time) and we’ve had some periods of even colder weather. Also my T4R was spending 50% of its time in 4WD just to get into town and home so all in all I didn’t think maybe the mileage was too bad (13 to 15 mpg). Plus I use fuel with 10% alcohol most of the time which will affect the mileage slightly.

alotawatts

This may have been mentioned already - but a valve adjustment can often improve milage.

mkgarrison5

i get roughly 18mpg with 70% highway and 30% city. i drive her like a normal person haha.. nothing i have done has changed it.. maybe its just the nature of the beast.. i have not cleaned the maff sensor but thats next. maybe today... it could be worse but hell i figured i would get better mileage since the new plugs and fuel filter

surf4runner

no.