right now I am getting 10 city and 12 highway. it should be getting about 17 and 20. I dont have any idea why. the engine is very smooth, the RPM dont run high. no indicator lights are on. its an AT that is shifting fine(just had the fluid flushed.) I would say i am taking it easy on the gas peddle.l i think the tires are 31 inches.
an example: i just drove it des moines from MPLS this weekend. its about 240 mile drive and I couldnt make it on one tank.

I do need to get it fixed with gas prices being what they are.

What could it be?

What vehicle are you driving? And what engine does it have?

its a 1990 4runner sr5 v6. its 2wd but can be put into 4wd.

Do a tune up and replace your o2 sensor.

I was planning on a tune up. how much could an O2 sensor cost?

An OEM o2 sensor will cost about 100 bucks.

try the fuel filter and air filter and 02 sensor also clean the injectors. these are the most common issues.

And make sure your tires are properly inflated.

thanks for all the help. I just layed out $450 to replace the valve cover gasket(I think) so now I gotta wait a few weeks before I do all this, but it will be worth it if I can get better MPG.
Julian

First, how do you calculate your mileage? May seem like an elementary question, but you would be surprised.

Air pressure in tires, air filter, plugs, wires, cap, rotor, ign timing, fuel filter,and o2 sensor are what I would look at first, assuming you calculate your mpg correctly... I never drove it afterwords, but my 22RE went from running great to running AWESOME after removing the injectors and having them clean professionally.

Also your truck is a 4wd truck, even running in 2wd its still a 4wd truck.

What trans do you have? With current driving speeds being higher than in 1990 I wouldnt expect much more than 15/18 from your truck...

How many miles on the motor?


Verify the tire size for us, and check the inside of the drivers door to see what came OEM.

the tires arer 31 inches, its an automatic and has 220k miles on it. 15/18 would be way better than 10/12.

What was the OEM size? and how are you calculating the mileage?

TIRE PRESSURE

But so you know, 10/12 is not exactly out of the "normal" range for a 3.0 automatic in my experience...

After checking your tire pressure (and keep it high - tires are cheaper than gas right now!), the things I've done that seemed to help are:
Seafoam
Plugs/wires/cap/rotor
O2 sensor

oh wow, i just noticed that this thread is posted twice... so should i respond in the other thread with this message too? and probably my last post too right??

haha.. dont worry, cause i did it in both

edited...refer to post below.

hahaha yes I am fishing. but I like this site better. thanx for all the help.
Julian

haha. I am fishing for answers. but this site was much more helpfull. thanx for all the help.
Julian
PS I am glad you dont think its the tires cause they are relativly new and I dont really want to fork out money I dont have to.

not to brag, but i have a 1jz pickup and i get 28 mpg with 350rwhp....go that route..lol

seriously...more power..cleaner look...costly at first. but if you plan to keep for awhile...those money add up in savings from engine maintenance (1jz more superior then 3v motor)...and miles per gallon.

Great suggestions from the other responses. Do the free stuff first then work your way up to the more expensive items if you do not know what is causing the bad mileage. If you are using E10 regular you will also notice a drop in mileage with the ethanol blend. All that said, a sudden drop in mileage is usually points to the oxygen sensor. Go to an Auto Zone or Advance Auto and get a scan done , for free, to see if there are any codes in your computer. Finally, your catalytic converter may be starting to clog.

My $0.02