horrible gas milage

i just got a full tune up done on my taco and my mpg has gone horribly bad. is there a common proublem that happens with tacos any advise on were i might start dont have enough cash to go to a shop, a little bit of mechanical abillity

 

Bad O2 sensor?

 

What all did they do when they did the tune up? How many miles on the truck?

 

Can a bad o2 hurt your gas millage

 

yes but It wont normally hurt you that much. and "normally" if it is THAT bad it will set a check engine light

 

maybe the way you're calculating it?

 

Yeah, I would first check your o2 sensors. Mine were bad and I got shitty mileage. And after the new ones it jump up about 3-4mpgs.

But driving style does effect it also, If im hard on the pedal or drive more agressive my mpg's will go way down on a tank.

 

Well I read somewhere (when gas was $4 a gallon) that a bad o2 sensor can reduce your mpg by 40%

 

my 00' 3.4 gets 13 mpg, uphill, downhill, with the wind, against the wind, and in neutral. I don't know what to do with it.

 

Hmmm did they change the plugs? Maybe the wrong ones were put in or not gapped correctly.

 

I had the wrong oil put in another car of mine and it change the mileage. I changed the O2 sensors on my 2000 V6 4x4 and started getting 19-20 out of it...22 on the highway. I'd like to change them on my current truck but they are EXPENSIVE

 

Haynes repair manuals help me a lot. you can get this at your local auto store. I got mine from Auto Zone. try getting one, it should narrow down the problem.

 

I have the same problem. Mine used to get 16+ in combinded driving. 20+
on the freeway.

Took a 1400 mile road trip over Thanksgiving, just under 19mpg, but now that I am back I am getting under 14.

Plugs were changed at dealer, o2 sesonsors both have been changed.

Thou when the 02 sensors were change he checked obdII and showed something was running rich, this was with a cold engine.
Passed CA smog with no problem

Could not get to all injectors to test because the Supercharger is in the way.

Only other thing change tires, same size but now running Bridgestone revo II's. I did read a lot of people said they had a mpg drop with this tire, but over 2mpg?

My neighbor has a full size v8 Chevy truck and gets 20mpg

 

Whats horrible?

 

OP... what did they do for the "tune-up"???

I changed all my fluids/plugs/air and fuel filter a little after I got my truck and didnt notice any mpg change. The previous owner did all the services regularly so I didnt expect much.

I went from 265/65/17 grand trek tires 20-22mpg to 265/70/17 goodyear wrangler 18-19mpg to my winter tires firestone winterforce 265/75/16 16-17mpg all highway #s so tires (size/brand/tread) do make a difference.

 

Whats the MPG you are getting? what are you driving V6 4 cyl auto/stick?

 

My MPG has gone down a little too lately. I'm thinking it could be due to the winter gas they have switched to. During the winter months, companies use different types of additives then they do in the summer time. At least here in Cali anyways. Not sure in other states.

 

I always get worse mileage in winter and especially in colder weather. Our trucks are notorious for being whiny about cold temperatures. I can get 23.5 on an all highway tank in summer, and in winter I get 18. Blows.

 

13 or so maybe 15 with some hiway driving.

used to be 15+ and 18+ all hiway 19 now. 21-22 before.

At $4.50+ per gal it sucks.