2011 TACOMA GETTING 10MPG!! please help

Howdy everyone! and thank you for the help!

I got a 2011 6cyc 4.0. with only 86,000miles. About 8 months ago I was getting around 300 miles a tank so about 16.6 mpg which isn’t good but I do have 285/75/16 10ply tires and a full metal rear bumper/roof rack. Now I am receiving about 12-10 mpg and I'm not letting it go above 3000RPMs. I did install the “Pedal Commander” a while back then returned it but even with it gone I still get the same gas mileage. I have cleaned the MAF and the throttle-body, no change... I've done 2 oil changes since it happened. also I installed new spark plugs from the Toyota dealership. I just got the BlueDriver OBDIIreader so I can check a whole bunch of things but I don't know the correct values the timings/intakes need to be at..... Currently, I have 157 miles on this tank and I have 1/4 tank left. Anything helps! thank you again!

 

What other mods have been done to the truck? Lift? Armor? Winch? Skid plates? ????
What is in the bed?
Driving style?

 

Any check engine light?

You might start with your Long Term fuel trims. - You will need your scanner for this.
Might as well have a look at short term too.

If they were too bad, you should get a check engine light.

 

I haven’t put anything on the truck besides the roof rack and some lights since I got it 2 years ago. And bed is loaded for camping most the time but it used to get 300 miles per tank easily fully loaded.

 

No lights on, what % should the Long Term be at?

 

ideally within 5% +/- of 0
Over 10% is when I’d start looking for a problem.

 

Okay I’ll look at the next. Should I be driving or idling ?

 

I'd look at them over various driving conditions, also look for any discrepancies of fuel trims between bank 1 and bank 2 (they should be pretty much the same)

 

It doesn’t really matter for Long term. That’s the one that tell you more in your case.
What we are looking to see is if the truck is pulling fuel or adding fuel.
Positive (+) number means a lean condition. Negative (-) means a rich condition.

 

O2 sensors and catalytic converters should be checked as well.

 

BTW OP, take Dm93’s advice over mine.
He does this stuff for a living.

I on the other hand, don’t.
I just fix my own stuff because I don’t like spending money.

 

Hey, same here that’s why I spend more on gas

 

Okay I’ll go out and drive around tomorrow and note what’s it’s at. Thankyou !!

 

Okay I’ll check those as well. And report.

 

Like I always say, I’ll either make it better or a whole lot worse.
And I can guaranty the guy that fixes it after me, will work hard for his money.

 

Down stream can affect upstream, just as upstream can affect downstream.

 

So I did a little bit of driving just around town today.
long term fuel trim bank 1 was at -14.8%
long term fuel trim bank 2 was at -11.7%
So I’m guessing it’s running rich which explains the bad gas mileage but how do I fix it? Thankyou again everyone for the help!

 

You mentioned you did the throttle body cleaning. There’s a small vacuum hose that can pop off in the back near the clip for the air filter. It may have come off not sure if that would effect your mileage but its just a thought

 

Just did some reading and saw that anything over +/- 10% should set off a code.... but I haven't had any codes

 

What is your MAF readings with engine warm @ idle?
Start with the easier stuff first.

I don’t know the exact spec off hand but some where around 1 gram per sec / per engine cubic liter.
I don’t see a spec in the FSM, but then again. I don’t have access to the full FSM.

Maybe @Dm93 knows the the spec range.

Until then, just let us know what it says.
Also, check coolant temp and IAT.

If these are normal, you might have a look at the A/F and O2 readings.