2012 Tundra 5.7 Getting 6MPG Mystery 95% Stock

Brand new TRD filter. Fuel filter is in the tank attatched to the fuel pump.

 

I highly doubt it. A female owned it and itvwas beyond bone stock.

 

Would this trip have reset to zero when I disconnected the battery for an hour??? I was trying to reset the ECU. This is the amount I just put in 2 days ago and topped off 4 gallons tonight and reset all to zero. Lets see what happens. Funny how it says 341 mile range slap full and I got less than 200 miles out of my first tank. Hmmmmm

 

We shall see.

 

It always does that when you disconnect the battery. It will go down.

 

Drive the hell out of it for a couple tanks. I wonder if E85 was put in there even though it isnt flex fuel. I put it in my FFV truck once. Gas mileage sucked balls. took a few tanks to get straight after that.

 

Possible bad A/F sensors, viscous fan hub staying engaged, or lots of short trips and idling.

I’m not at all surprised you burnt that much in 2.5 hours idling.

What size / type /load rating of tires are on this thing?

 

Have you change the engine oil yourself? What viscosity oil is in it? I know some people still like to run 10w 30...40, etc. It calls for 0w20 or 5w20.

Also, if you just reset the computer, it almost always shows worse Average MPGS than you actually get. I would run a few tanks through it then check it or manually calculate it.

 

a old engine will suck the gas due to a loss of power

 

Say what?

 

Maybe an old engine with bad rings not that much.

 

275 65 18

 

I was told they put in a synthetic blend. I want that shit out of my engine. I want Klotz in it uy I am waiting to see what they say

 

Im on it!!!! I suspect the cats!

 

One thing you could check is if the choke is mode is not on all the time, i had it happened to one of my other vehicles. What it ended up being was a bad connection to the ECU, dielectric grease solved the problem. When the choke (extra fuel) was on it started up normal but after it warmed up it would idle rough and you could smell plenty of unburned fuel. I think you did mention that someone did a new thermostat, it could be possible that the sensor in the throttle body may have some blockage in the coolant lines coming from the engine, that had happened to me on an older Toyota as i remember and had to be cleand out.

 

The tundra pulled the freakin space shuttle so it can pull that

 

Maybe frozen ebrake?

 

Update guys: First of all than you all for the input. I am grateful. I cleaned the throttle body some more and put 3/4 of a can combustion cleaner down the throat and let it sit. I have never used 87 or 89. I have always used 93 octane. Now I know this will stir a serious debate but I stay true to my proven 93oct at my shop.

That being said. I checked every vacuum line by removal and bend with a flashlight ,i even submerged them and water tested with compressed air and zero leaks. I looked everywhere in my immaculate engine bay for any signs of wire chewing and zero. Did a serious Corrosion X HD aviation Grade treatment on my battery posts and Pos & Neg wires to the battery, tire pressure, alignment, brake inspection, 2 tank treatments, filled it to the top with 93 , added Klotz, reset everything to zero and 8 hit the Turnpike at 4 am.

My girlfriend and I drove from West Orlando Fl down south to Port St. Lucie Fl to get my daughter. I was stunned to see I did over 287 miles averaging 75-80 mph there and back and still had a 1/4 tank to spare when I got back to my shop. 16.2 MPG was the best it did for the short trip.

 

Sounds on point for mpgs now. Keep it under 70 mph and you could see 17-18 mpg. Good luck with that though! Every time I tell myself I’m going to try to see what gas mileage I can really get, I can’t keep myself going that slow on open highway.

 

So what was the main culprit?

 

Honestly I dont have a definitive answer. I just went through doing what I do ensuring everything is 100% . I also got every bit of shit 87 gas out and swapped all 93 in with Klotz. Over time the 93 will clean the filthy valves from 87 oct all its life. When my Klotz engine oil gets here I can slap that in with the TRD high flow oil filter and I will be golden! TRD Exhaust next!

Update #2 Just made a run across the state last night topped off to full and I literally made it here and burned only a 1/4 tank this time not a half a tank like the day I drove it home from the dealership!!!!!!! Wooooooooooo

 

This.

 

So sounds like maybe some shit gas.

 

Update #3 Truck is running amazing! Just went from the west coast of Florida to the east coast and back to the middle of rhe state and still had more than a 1/4 tank left! Hell yeah!!!! So I stopped at the Toyota dealership and picked up my TRD Cat Back Exhaust. Super stoked. Rims and Tires going on by Friday too.

 

Update #4 finally stopping for fuel up with 93 octane again. I still had more gas to burn but I was headed across the state east bound and want about to use a crappy old gas station off the beaten path of hwy 50. Im blown away at the difference. I probably could have made it to 375 miles or more on this 1 tank.

 

Don't know if someone mentioned this already but when i bought mine (used) it was averaging 10mpg for a while and I was really babying the throttle.
Finally realized the truck probably was idling a lot or being abused (hope not) before I ended up buying it so I reset the display. Now i average anywhere between 15-18mpg depending on where I am driving. Maybe not your solution but it was my issue.