Diminishing MPG.... why is this happening!?

I typically see 15.5 to 16.5 in the cold winter months probably as a result of fuel. I really never do any better than high 17s though unless I'm on the highway for more than half the tank. I chalk it up to the manual gearing and lots of hills in the area. And a heavy little truck with terrible aero plus a motor that needs to spin past 3.5k RPMs before it can get out of it's own way.

 

I asked if he got e ply and didn't know. I think that is what's going on here.

 

Tire pressure is a compromise between many things.... tire life, ride quality, load capability, mileage, traction.....

Probably the best way to determine the correct pressure for a different size of tire would be to do the chalk test.... and maybe adjust from there depending on needs.

 

Tires can have a big impact as well as the quality of the gas....


I'd take a hard look at the air filter though. If this is one of those oil lubricated filters and some of that oil coated the mass air sensor, then it might affect how much gas the computer is putting in the engine.

 

5-30 will cause a little bit of mpg loss on its own. Why would you run that in Phoenix?

Edit: Guess it might make sense in the summer, anyway.

 

This caused major mpg loss in my 1st gen Taco.

Go buy MAF Sensor cleaner at an auto parts store, remove the sensor and spray it down...

 

Holy crap! My 2014 with a leveling kit and 285s (R.I.P.) only got 14! It said 13.5 on screen but I figure 14 since the tires were slightly larger than stock.

 

I can’t seem to do better than 15 MPG as of late on my stock Tacoma. I never expected to get the 19 MPG City advertised on the window sticker, but I consider 17 MPG to be a reasonable expectation.

 

I've had my truck for 24k miles now and I've seen my mileage steadily decline. No suspension mods or new tires yet. Just a cap and some sliders (for the real weight adders anyway). I run my tires to be around 33psi hot.

That said, in the past month or so I've seen a decent sized drop from my average around 17.5ish to 15.5-16.5. (So, long after the switch to winter gas) I too have been a little easier on the pedal, after noticing the decline. Not really sure what gives, and over the 24k, I haven't noticed much a difference in mileage whether I drive like grandpa, or more aggressively. I think the best average I've gotten is around 18.5, and that was when the truck was new.

I've seen a lot of posts of people getting 20+ with lifts and tires. No idea how they manage that, unless they're going 10 under the highway speed limit? For sure keeping the truck below 60mph would do wonders for our mileage...

Dreading the mileage I'll likely get after the lift/tires. Ironic how my "road tripping" mobile is the one that will get the worst mileage. But tha'ts what you get when you road trip to places to offroad/camp.

 

I have to admit that when I upgraded to 265/75/16's (and this is a p rated tire) I cant get over 18mpg on a road trip. When i had the stock 245/75/16's and the front air dam still on the truck i was able to get 24-25 mpg on a road trip and this was stock off the showroom floor.

I also have a soft roll up cover...I read somewhere that others loose gas mileage over these as weird as that sounds to me.

Oh and i put mud flaps on and maybe that adds drag?

 

37.5 to 38 psi is the magic spot for this size of tire. and my TPS measures lower so this turns out to 36PSI for the TPS but its really 37.5 to 38 psi

 

For me only (not speaking for others) the handling is just too sloppy at this low of a pressure

 

Ok to answer everyone question about what load rating my tires are here is a picture of the sidewall info because I'm not exactly sure.



I'm loving all this feedback though, I didn't think this thread would catch on and supply so much info. Keep it coming!

 

Could be your Crank Position Sensor going bad, I know a guy on here @bshammer0 who lost like 3-4mpgs due to this

 

Ever notice that during colder months, you see more complaints about poor fuel mileage? Or when someone complains that they have no idea what could be causing the drop in mpg when in reality, they've done some mods like a lift kit or bigger tires (or both), or the weather (big culprit), or the extra weight they're carrying (like I am), or the more frequent short trips they're taking, or their commute has changed, yada yada yada. In most cases (I'm guessing like 99% of the time) it can be explained or understood if you really look hard enough. Or you can just whine and complain and look for sympathy.

 

http://www.falkentire.com/tires/light-truck-suv-cuv-tires/wildpeaka/t3w-tire

Chart says SL.

 

+1 on the seafoam. I do it once a year on all our cars.

 

Placebo or not, this worked for me -->

https://www.tacomaworld.com/threads/bad-gas-mileage-for-no-reason-try-resetting-your-ecu.589600/

 

Based on the max PSI of "51" my guess is Load Range "C". Most "E" rated can support pressures up to 80psi.

 

Also having this issue, But I did recently get new tires General grabber at2 265/65R17. I also had the transmission programing redone due to bucking when coming to a stop. so not sure which one affected it more. I know the tires are heavier. But i went from averaging 18mpg to about 14mpg now. I expected a drop but not that much.