ok i'm really getting sick of this 9-11.2 mpg crap. i really dont know what else to do accept to bring to a dealer. it has been getting worse for a wile now. i keep up my truck very good with oil change every 3k with Amsoil 5w-30 synthetic oil with motocraft filter. i also have 90$ set of Belden wires with autolite platnim 2 plugs. cold air intake, flowmaster 40 si/so, 4.10 rear LS, 265/75r16 bf at's.

before when i fill up i would get 30miles before the pin would move off the F but now i'm getting 9-16 miles till it moves off.

i know the cold is bad but everyone still seems to get better then me.

IS THERE ANYTHING ELSE I CAN DO BESIDES SPENDING 400$ on a tuner?? i was thinking on that screaming demon coilpack but idk if it worth it for like 1mpg

my friends Dodge ram gets 11mpg with 4.11 5.9v8 and a really heady foot

 

I'm going to piggy back on this if you don't mind. Here are the things I have tried if you haven't yet:

Proper inflation of tires
New spark plugs
New spark plug wires
New o2 sensors
Clean Air Filter
New PCV valve
New Fuel Filter
Sea Foam in gas tank and through brake booster line
Fuel injector cleaner (fixed my long starts)
Switch to keep a/c compressor off

I have the 98 3.0 4x4 with 4.10 LS and 32x11.50 at tires 83k miles.

The next thing I'm going to try is cleaning my intake parts:

Mass Air Flow sensor
??? don't know the other parts, someone help please???

If you haven't tried everything on the list I gave maybe you could give it a try.

Marc

 

i have not done o2 sensors or pcv valve.

i did the rest. what are you getting for mialage?? ^^

 

i was getting about 14.5 until the last 2 tanks when i got 12.

 

O2 sensor gone bad could cause this

 

yea i gained 4 mpg changing 02 sensors

 

if i had bad o2 sensors wouldent that throw a code telling me it was bad?? they probaly havent been changed since truck was bought in 99

and how hard is it to replace the o2 sensors? and how many i got? and how much are they? and what brand is good if they got like a performance one or something??

also i put super gas cause they were having a deal super 92 for reg price 2.03$per/gal so i got a full tank and added lucas gas additive seem a smidge better and a whole lot smother driving and seems like i dont have to press gas pedal down as much to go as fast and rpm seem lower.

 

our trucks were not programmed to take the premium fuel..stay with regular..
if im thinking correctly theres 2 o2 sensors..ones on teh pass side header and the other is behind the last cat..crawl under there you cant miss them there sticken straight up out of the exaust pipe with lil wires comin out of them..

 

are there better ones to buy like thoes bosh platnum coated o2 ones? and will it throw a code if its bad? how many miles till you should change them?

i only got the super since they didnt have reg or middle grade so i got super thats the only time i got it i knwo they not soposto run it but once cant hurt it.

 

nah wont hurt it just the truck isnt set to benefit from it..waste of money but if thats all you have then you gotta do what you gotta do..the code "CAN" be tossed or cant be..i had a few cases where they were jsut reading crappy but the computer figures there ok and jsut dumps more fuel in to make the readings right..go to ford get some new ones or autozone they all have warrantys so no worrys there..toss a couple in cant hurt!

 

ya cant hurt. if it gets me a lttle bit better gas mialage i cant complain lol.

can anyone else think of anything i can do to make it get better gas mialage?

 

might be ur tires. hell, my 265/70s are ALOT bigger than my 245/70's so that could be ur issue right there

 

what kind of gearing you have?

 

4.10 LS, i have had the tires since last fall and it was the same then as in now but its just worse now. last years winter i was down to 6mpg i almost drove it into a tree but i remembered i dint have collision insurance lol.

 

i think its just the cold... im at 13 right now or close to that and ive never gone below 15

 

thats what i'm hopeing on cause 35$ every other day is killing me man!!

i might change out 1 o2 tomorrow and 1 next week cause i think there like 50$ each right? i need to save the other 50 for gas lol

 

wow..cold air should be better..up here its cold like -10F today and my truck runs better when its cold then when its hot..an engine thrives on cold moist air..hot dry air gives my beast worst gas mileage..

try a can of seafoam too..clean everything up

 

There is is no guarantee that new O2 sensors will help ... but they might. The ones you want to change are the two that are upstream of all the cats. Depending on which engine you have, they will either be in the exhaust manifolds or toward the front of the y-pipe.

The O2 sensor after or between the cats has nothing to do with mixture control; it just provides a way to judge cat efficiency. Don't waste your money changing it because it cannot improve your fuel economy.

In answer to your other question: you will not necessarily get a trouble code right away for oxygen sensors that are on the way out. The diagnostics has to provide enough range to allow the sensors to their job. Your mileage could drop considerably before reaching the code threshold.

You could also try cleaning the MAF sensor but I would forget about a coilpack swap as a means to significantly better FE.

 

You got that a lil backwards. Colder air is more dense and therefore requires more fuel. Whereas, warmer air is less dense and will use less fuel. Cold air intakes that advertise better fuel economy only really work when they are joined with an exhaust.

 

i just sea fomed my truck last fall and cleaned my MAF with that special maf cleaner.
so u think i should skip the o2's?

so far wunning this 92 oct i seem to be getting better mialage its between 1/2 and 3/4 of a tank with 64miles. i have been normaly getting 60miles to a half tank so thats good.

 

how many miles are you getting to a tank?

 

I looked quick at these posts and I did not see one certain questioned asked.
How long do you let it idle to warm up in the morning? Idle equals 0 MPG. My worse mileage is to work. I live 2 blocks away so she doesn't get a chance to wram up. When only going to work I get 15 MPG. 4.0L, 5 spd standard, 4x4, 4.10 gears.
I start her up in the morning, clean the windshield if need be and go. I drive all my vehicles like this and they all have high mileage.
Vehicles vary in MPG even same make, same model but when you were getting better and it dropped that much I would look for some other BIG factor and that is usually how we drive. Unless someone is stealing your gas each night?
All those changes you and others have posted normally do not add up to that big a change as you mentioned.
Is it in 4WD and the light stopped working?
If it's an automatic is the transmission shifting properly?
Is there a fuel leak?

 

i let it idle for maybe 2mins tops on a cold morning.
its not in 4x4 cause i prop would of broke something making sharp turns on dry pavement.

it is shifting properly new tranny at 80k

no fuel leak would have smelled or seen spots near tank area.

 

lol 170ish to 180ish with hitting the dummy light

 

Holy mother, it is like 10 degrees here and I am still getting about 280 to a tank, I am pushing 350-360 in the summer.....