Bad mpg's

Last week I change my plugs, put in an OEM air filter, changed my fuel filter, and seafoamed. With my lift and tires going about 70 mph to and from work I would get about 15.5-16 mpg's now my scanguage is showing about 14 mpg's and when I checked it last I only got about 14.5 average. Anyone have any ideas as to what is going on? Also I have a low idle with it in gear and stopped it is around 500 rpm's any help?

 

I wish I got that. But you have stock tires and no lift lol a good reason why you get 21. I have not noticed that I am driving differently it is all highway to and from so steadt 65-70 mph all the way. I know that is not the best speed to go when trying to get better mpg's.

 

Yea me being 4x4 is not helping lol at all but before I could get 16 out of it. My tires are 305/70/16 I think that is about a 33-12.5

 

have you had your 02 sensors checked?

 

How you check an o2 sensor?

 

No I have not. How do I have them checked?

 

Check your air pressure! Raise it closer to the tire's max... 32 if stock BFG's (a 35 psi tire).

My mileage was below 16 mpg recently, and while I am usually good at checking the pressure... it was after our last Baja trip when I did... and perhaps due to hot air when I set them at 35 psi, but when I checked this weekend it was down to 30 psi... The Hankooks are a 44 psi max. tire and I found 35-40 to be ideal. I put the fronts at 38 and the backs at 40 and I got 17.4 mpg last fill up (was mostly freeway driving).

 

I think the max on my tires are 50 psi I have Mickey Thompson Baja MTZ's I run about 36 in them.

 

Sorry to thread jack but I got 20mpg last weekend , highway miles but still good

 

Good for gas mileage, but bad for tire wear. The middles of the tires will wear much more quickly than the rest of the tire. Also you will get less traction doing that, especially wet traction. You will hydroplane much easier. Best way to set tire pressure is the chalk test. If they are underinflated you will get less gas mileage and outside of tires will wear more, overinflation, see first two sentences of paragraph.

 

i get 9... like a boss

 

Yea Im way stoked. I got 21.1 (Stock wheels and tires though) City/Highway 50/50. Super excited to see those numbers out of a Double Cab long bed.

Op, have you had your odometer recalibrated? Also yea, check tire preasure.

 

Nope have done nothing with the odometer and since I am at work now don't have a chance to check the pressure. As soon as I get home I will though and then look into having my 02 sensors looked at.

 

Not true on all tires... as I said "close to the max. rating" The chalk test will tell if your wear is even or not.

My Dynapros at 40 psi are wearing EVEN at 8,000+ miles (they were rotated at 5,000 miles). They are 44 psi tires.

I am not saying to go to or above the max. tire rating (it is on the sidewall)... but close vs. under-inflated.

 

I feel that with running about 36-38 psi has done me good. I get good mpg's and tire wear is good also. I have around 40,000 miles in these tires and still so much tread left. I may be low on the pressure in them and that may be why I am getting worse mpg's it is just funny since I did the work to my truck that I then noticed it.

 

Still curious on how you check an o2 sensor. Maybe mister Rhino will enlighten us. Then I always thought the rule of thumb was 100k miles or a check engine light would be the replacement intervals for them.

 

I am super stoked too, since I am running 33x12.50s and a S/C....

 

Damn you are getting that with the S/C hmmm maybe I should put mine on and see if that helps. Also I am double cab not much but still more weight.

 

Agreed. With how many factors there are in setting the tire pressure, there is really no set pressure you can really use. It is trial and error. I personally have found the chalk test to be the best. It accounts for the kind of tires and sizes and the weight of the vehicle. I had a truck with 285 nittos on it and the rears ran at 40 and the front left ran at 37 and front right ran at 38. Trial and error.