Smallwood0507

Alright so when i bought my 4runner last year it got 16 mpg and after 1 year and new tires (bfg's) it now gets 12!!!! Whats up with that i knew the bfgs would take off a little mpgs but 4 that cant be right....Any guesses to what would be going on???

BigBallsMcFalls

bfg can drop mileage
how you drive has a lot to do with it

get a scangauge II and figure it out

vital22re

iTrader: (2)

check the tune up, maybe replace the primary o2 sensor, clean the maf. how fast you driving on the freeway? keep the rpm's under 3000

Ironmike4x4

First off, how much bigger in size of tires did you go to? You will have to remember 2 things. Bigger tires= more weight and more drag; therefore, more load on the engine. Also you will have to realize the mileage will be off due to the change in tire sizes so there will be a difference.
Secondly you may be in need of a tune up as Vital said. If you can get a technician with a scan tool that can read O2 sensor parameters then they can tell you if it's reading properly. If you have a dead or lazy O2 sensor then it will affect the air/fuel ratio causing poor mileage and will not always turn on a CEL.
Finally, your cats may be on it's way out. The same technician can read this on the O2 sensor parameters by checking the post catalyst data.

96743runner

x2

But like others said earlier, it is probably the tires and your driving style that may be giving you that gas mileage.

nuke1105

how many should i expect from my cats? I had a 4 cylinder taco and only got 80K miles out of them because they were pluged up due to lack of maintenance (my first car at 16 didnt know much). But now i have a 6 cylinder and im real anal about the service of this truck but since i bought it used how can i tell if i still have the originals and how many miles should i expect from them?

Smallwood0507

So my old tires were 265/70-16 and the new ones are 265/75-16

MaK92-4RnR

Tune up, check the o2, keep RPMS under 3k. pretty simple things that help out. theres some modifications you can make to your truck, like exhaust. but with bigger tires and whatever else, you wont see more than 14-16 mpg... its just how these trucks are.

Kiroshu

Any codes? Tune-up? Sure your doing the gas mileage math right? Dirty airfilter? Crazy drving?

Smallwood0507

Checked my gas mileage with the difference in tires and increase it to 13....still not great...but ive been driving normally...airfilter was new 2 months ago....the idiot light is not on if thats what you mean by codes

Kiroshu

13mpg for ur trucks not right..... thats about what my truck gets and its a 23 year old 22re 100% original with 31 10.50s soooo......... yea.... You have not reset the computer resently have you? or disconnected the battery recently? You may have stored or history codes which usually don't pop the engine light you need a scanner..... are you carrying a bunch of weight in ur truck? Synthetic oil? Gas leak? check fuel system and make sure its buttoned up good. vac leaks? make sure theres none.

Smallwood0507

Hey thanks your your help man, but i havent reset the computer or unpluged the battery....my buddy has a scanner so ill hit im up for some help this week....I do have golfclubs and a 12" sub that i always carry around, but thats not too much weight....hmm oh something else it that it is supercharged (bought it that way) and that things been on their for something like 100,000 miles + so something may be wrong there

Kiroshu

Whats the air pressure in your tires? Is it all even? Truck badly out of alignment? Brakes draging?

Smallwood0507

Running 36 psi which is what discount tire put in them...alignment was done last week and i dont believe that the brakes are draging at least from what ive noticed

Kiroshu

Make sure they are all 36 atleast the back ones.... if its uneven it will cause mileage to suck.... someone might be stealing ur gas......

Smallwood0507

the tires are brand new too by the way less than 400 miles on them.....but i really hope not i do park outside every night

brian2sun

Someone wouldn't just steal a gallon or 2, you'd have a full tank in the evening and an empty tank in the morning, so I'm sure it's a problem with the truck and not your neighbors.

When's the last time you changed your plugs and wires? No S/C here, but I get 16-17 average and I've gotten as good as 19-20 on the open highway w/ a lift, 33s, and 4.88 gears. 12-13 is pretty bad even with the s/c.

JWaldz

iTrader: (1)

I feel you on this one man. I noticed on my way to work last week that I burned a quarter tank in only 50 miles! 50!! That was the first quarter, too.. and I don't even have a heavy foot. I think it's time for some new spark plugs and wires, maybe some other things to look into as well. Good luck.

Kiroshu

If you have old ignition parts and or not OEM ones you can get a milage issue. If you plugs put NGKs or OEM toyota back in there for your best performance. Coils and wires maybe be expensive but if you buy them they better by OEM. Other than that theres really not much to tell you..... Your trucks not in 4wd all the time is it....? Is it extremely cold where ur at?

Smallwood0507

I havent replaced the wires or plugs since i bought it last year so it could be due....but its not in 4wd...i do live in the foothills of colorado and i gets down to 30s at night but didnt have a problem last year...