Sudden 4mpg drop

Jesus christ!

Don't tease me with Superchargers.

I would happily give up 6mpg+ for one of those!

Still hoping I can save up for it over next 2 years and still get one for a reasonable $6800 lol.
Then the fun self install.

 

Idling REALLY drops my MPG...I can literally see the fuel gauge change when sitting in my truck with it idling...I know I'm pig-rich on AFR but reduce your idle time if you can and see if that helps at all...that and knock your air filter out and see if that helps any I suppose...fuel quality change at all? I run 91 all the time but I get the best MPG when i use non-ethanol fuels (~1-2MPG difference)!

 

All possible, but unlikely.

6 year old truck with 60k miles, fuel filter dying would suck some ass.

Wheel bearing I would know.

Truck acts perfect in every way, not even one hiccup when running since I bought it.

Couldn't be happier, though as expected, I bought another Toyota 4x4 after all lol.

 

Thanks, will do.

Going to run next tank of fuel with no remote start if I can remember not to lol.
Will check the usual suspects like air filter also.

Same fuel, usually 7-11 gas 87 regular.
Tried non ethanol fuel twice, lost 1/2 mpg from doing that.
Truck is built and programmed to run on 10-15% ethanol so that makes sense.
Also tried running higher octane fuel, lost 1/2 mpg with that also.
Computers in modern cars are tuned specifically for the ethanol gas we get, and the octane they tell you to use.
They don't understand, and can not compensate for any changes to those.

Now my 93 Goldwing loves real gas, I lose several mpg when using modern ethanol bullshit in the carburetor.

 

So aside from the remote start possibility, I am leaning towards a bad O2 sensor at this time.

Even though that's a big pita, I will probably start there, and also check air filter, clean maf, and check wheels temps for dragging brakes.

I actually hope its the remote start lmao, even though then I spent all that money and install time for nothing

 

That's odd. I generally shoot for the Ethanol free 91 that a local station has, and I don't see any loss in MPG. I'm also only going off the dash computer because I wasn't really worried about MPG when I bought it. I knew I would be happier just filling and forgetting. lol

 

It is statistically within the margin of error, so who knows for sure.

However the modern computers are programmed for ethanol, and are not programmed for, or able to compensate for, real gas anymore.
This has been seen across many vehicles before.

This is about timing, and knock, so losing mpg is very logical, but also hard to prove definitively due to driving locations, habits, and situations.

Not sure if anyone has done a controlled lab test, but I wouldn't be surprised.

Best thing for every vehicle is to run what the manufacturer says to run, always.
Anything else, your off the reservation taking chances, with no scientific proof of any gains.

Ymmv, do what makes you comfortable and happy, with your time and money

 

I can see where you are coming from on it. One question though, does the Tundra (arguably a 12-13 year old vehicle) count as having a modern computer?

 

Indeed.

Yea it is modern lol.

See this > https://en.wikipedia.org/wiki/Ethanol_fuel_in_the_United_States

And this one is easier to read > https://www.historicvehicle.org/ethanol-timeline/

Basically is became a federally mandatory part of our gasoline in 2005, so all Tundra years are built for it.

 

Three things to check:
Tire Air Pressure
O2 Sensor
Quit Remote Starting

Report back.

 

Lol you live in Northern Virginia. I live in South Carolina. I don't even have a remote start and I can bet my temps and humidity win against yours! Suck it up man! It only takes the truck two minutes to cool down!
My method: Get in the 140 degree truck, start it, roll all windows down to let the hot air out, drive and within two minutes air is cold and windows go up. My thermodynamics class 30 years ago taught me it's much easier to cool 90 degree air down to 70 than cool 130-140 degree air down to 70. Get in, let it out and move on.

 

Yes indeed, more good advice, thanks!

Tire pressure was on the my list also, but to lose that much mpg I would probably need a flat, and I don't even see any tire squat so not likely.

O2 certainly possible and on my list.

Yea, will stop using that on the next fill up and see how it does

 

Before COVID, I used to sit on the highway at a dead stop at rush hour. I’d watch my avg MPG readout drop like a rock. It was amazing how quickly I’d lose those tenths.

But it always came out to the same as what I calculated at the pump. In my experience, the computer is still very accurate, even when factoring in short periods of 0 mpg. That’s just how much you’re really losing.

 

Your right about that, its definitely hotter down your way!

Coworker is outside Atlanta, and Aunt and Cousins in Beaufort neat Hilton Head.
You got us beat man lol.

Yea, dropping the windows and driving, then putting them up with AC is standard procedure with no remote start, always done that, great advice!

And my truck is only maybe 10 degrees over ambient temps.
That's why I bought white, and use sun shield every day

Now my black 98 4Runner, thats a hot bitch in the summer

 

Damn. Winters are brutal on my MPG then.

 

Yea, your right, it is pretty awful.

Almost makes me wish we had cylinder deactivation lol.

 

I said almost!

 

Emphasis on the 'almost.' I know any number of guys who own Silverados/GMCs with that.

*LITERALLY* every single one of them makes cylinder deactivation...uh, deactivation the first thing they do to it. LOL

 

I notice a fair amount of ping on hot days with 87 octane going up hills. 93 definitely helps there. Though I rarely put anything other than 87 in the truck.

I haven’t reset my mpg gauge in almost a year and it’s been stuck on 16.0 for a long time. And pretty much every tank hand calculates to either just over or just under that.

 

I've seen this question a couple times on the GM Trucks forum:

"I did an AFM/DOD/DFM delete and my mpg got worse. What could it be?"

 

Yeah, I knew that adding weight for gear and going with bigger tires was going to knock it, but I have been happy so far. Probably because of the 38 gallon tank and the lower fuel prices right now. If we get back up to 5 bucks a gallon I'll be crying, but I will still love the truck.

 

Well, they did buy a GM, so thinkin' ain't their strength... @ColoradoTJ

 

I still read these posts in the voice of Beavis.

And I have a high alcohol percentage.

 

Your so lucky!

I got one of the bad trucks, brand new stock with 53k miles I was only getting 13mpg mixed on very gentle driving.

About 16mpg pure highway long distance.

Now after the 3/2 lift its less lol.

Such is life.

 

Dammit! Who let the 1st genners out of their cages?

 

Mine is also a 4.6 so I get a little help there. But for me the window sticker of 14 city 18 highway has been spot on. Though I’ve gotten tanks under that due to idling and I got almost 21 on a road trip two summers ago. But it’s been almost always right at 16 with my mixed driving, mostly to and from work.

And yeah, keeping it stock definitely helps. I want to level it eventually but gonna keep stock tire size.

 

Ah that makes sense.

Can't really envy you there, I wish my engine was bigger than 5.7 lol.

Enjoy it man

 

Yeah, I do sometimes wish I had got a 5.7 truck, but I wish I had an 8’ bed more.

I should buy a second Tundra, regular cab and 8’ bed. Lower the rear slightly to match the front. With a supercharger!

 

I've always been lucky on the MPGs and beat the EPA estimates in every new vehicle I've had. This was a chunk of driving from SLC into Wyoming. It included a bit of idle for a quick rinse at a gas station no touch wash. Ignore the dust; I live in a desert.