Big drop in gas mileage 2.7L 2TR-FE

First time posting here! I would love some advice from folks familiar with the 2TR-FE.

I've got a 2009 with 175k on it, recently I've noticed a considerable drop in gas mileage, from around 25mpg highway to 22-23mpg highway. It wasn't a gradual decline, I habitually reset my trip odometer after every fillup and noticed a sudden drop.

Have cleaned the MAF and am planning to replace the spark plugs (~80k miles on the set) and spray out the throttle body next week. Also going to replace the two smaller vac lines on the resonator which have small cracks at the connection points and the PCV which has probably almost 100k on it.

My question is, would any of that basic maintenance help fix such a large drop in mpg? Seems like it's running rich based on exhaust smell, am really hoping the spark change plus throttle body maintenance straightens it out but figured ya'll might have a better idea what could be going on. The check engine light isn't on, which makes me think it's probably not something like an O2 sensor or the secondary air injection pump, would it be worth seeing if it's spitting codes without the light? Thanks!

 

Lots of things can affect mpgs but sounds like you are on the right track doing maintenance. Everyone loves to jump to extreme conclusions, good to see someone doing the basics first. Vac lines 100% fix if they have cracks/leaks, and yeah it's time for a PCV and plugs. From my own experience I did PCV & plugs around the same mileage and some of my best tanks were shortly after that so it is possible they are contributing factors.

Without knowing where you live, it's not unusual to lose a couple mpgs just due to colder winter temperatures, winter blend gasoline, and cold air making your tire pressure drop just a couple psi. I track every single fill-up in my own spreadsheet (yes I am an unabashed data nutjob) and no matter what else I change, winter temperatures are the #1 cause for mpg drop. Driving like a maniac is #2, tire pressure is #3 in my opinion.

Do your maintenance and keep watching the mileage but I wouldn't sweat it too much. Wait until spring/summer and see how things change over time. Good luck and welcome to Tacoma World!

 

Lots of things can cause that as mentioned. Could be not engine related as well; frozen or sticking calipers, bad wheel bearings, basically anything that going bad takes more power to keep the truck moving. I routinely lose that on winter blend fuel though. Are you using oil? Coolant?

 

1-2 mpg is nowhere near a big drop. My 4.0 fuel economy always drops a bit here and there sometimes. Could be a bad batch of gas, weather etc. Many small variables can drop a few MPGs. Even slightly low tire pressure could lose you a few MPGs

I would log some more miles before freaking out.

 

I’d switch the rear diff oil to synthetic and replace the spark plugs with

$39 NGK 6619 Iridium Spark Plugs LFR6AIX-11 - 6 PCSNEW

NGK 6619 and buy 4 new Standard Blue Streak UF495 ignition coils and see what happens

 

It's been about 5k miles since I noticed it drop has been consistently lower the whole time so figured it might mean something I should look into.. thanks for the advice! Probably mostly just winter blend gas like ya'll been saying above but haven't noticed anything that significant in prior winters.

 

Nah not losing coolant or oil, no visible oil leaks

 

25mpg to 23 mpg - could be as simple as bad gasoline.

Try a different brand of fuel

 

Did anyone mention the air filter? Depending on driving conditions and dirt in the filter, it can greatly affect mileage.

 

Clean the maf

 

Thanks, didn't catch the abbreviation reading first time through.