Sudden Loss of Gas Mileage

I've searched the forums and can't find a thread that fits this scenario.

I've driven my 2015 Tundra 1794 for about 21 months before a rare snowstorm hit the area and knocked a bunch of trees down. I used the 4WD for the first time in 4H only.

Prior to this snowstorm, I consistently averaged 15 MPG commuting to work and 17+ MPG on a long trip. This is all on factory tires/rims.

After coming out of the snowstorm and disengaging the 4WD to drive normally again. My commuting gas mileage is consistently 13 MPG and my long trips are barely 15 MPG.

I took the truck to the local Toyota dealership and they suggested cleaning the induction system, intake valves, and throttle plate and adding a solution to clean the fuel injectors...

After all of this, no change in MPG! And no feedback from the service writer on the use of 4WD as a possible reason. I sense a very slight tension in the truck that I did not before, but I may be wrong since I'm trying to think of a reason for MPG loss without a tire/rim/lift change.

Is it possible that the 4WD has not fully disengaged? Any other thoughts?

 

You'd know if the 4wd didnt disengage.

 

Agreed. And I've engaged and disengaged it again to make sure.

 

The rest of it just doesnt make sense, hence you reaching out.

How many tanks have you been hit with the loss at?

 

Are you calculating your MPG's by hand or relying on the trucks computer?

 

Calculating by hand at each fill-up. The snowstorm was Jan 7th. More tanks than I can count and at least two 4-5 hour one-way drives and back, and a couple 1.5 hour drives. I've been monitoring this for awhile and figure this board would be a last resort.

 

Maybe a weird blend make it to your stations causing the drop in fuel economy.

 

I can't imagine that... I have a couple friends with trucks and they have not noticed anything. The first thing I checked was the tire pressure after having a discussion with them.

 

I live in New Jersey and October 1st to April 1st they have winter blend gas here
My mileage drops down to what your talking about 13---15 mpg after April it goes back up to around 18------21 Mpg Highway That's with my 2018 5.7 but I did notice after towing my mileage would not automatically go go the mileage before the towing maybe it's because it take the average of the gas in the tank , maybe your getting bad gas, go to a differant station, I only use Exxon or amoco not bp even its supposed to be the same. I found one Amoco station by my sons house and always get better mileage , you might have gotten bad gas Go to another name brand station

 

I will try that. I do gas up at Sheetz locally, but on long trips, I have gassed up at the most convenient station.

Thanks for the advice!

 

Might wanna check that all your brake calipers are functioning properly, since you felt a slight tension.

 

Will do. Thanks.

 

Hit your rotors with an infrared thermometer after driving. I thought I had a caliber hanging up on my boat trailer so I did this and compared to the truck. Both were right around 125 degrees.

 

They are telling you to check the rotors to see if one of them is hanging up? Great advise ,this is what you can do very easy way to check
After your driving awhile stop the truck get out and put your hand on the rim they should feel the same if one is hot that's the problem Check front and rear too.

 

After driving get out Nd feel the rims if one is hotter than the rest that's the one that's hanging up but I would suspect it's bad gas

 

I just had a similar problem as the OP. I used 4WD on Sat and my gas mileage after that was cut in half.

I put the truck in 4lo, drove down my street a bit, then went to 4hi and then 2wd...it took a long time to get out of 4hi, but the problem went away and my mileage returned to normal.

 

Drive your truck and engage and disengage. Allow it to cycle fully each time. Repeat. Repeat.

 

If you believe one or both front wheels are still engaged. Raise the front end of the truck and rotate each wheel by hand. The front drive shaft should not rotate.

 

If they are still engaged you would notice as soon as you turned a corner.