Post-5k service MPG drop??

Hey good people,

I've had my 1794 back for a few weeks after its 5k service at the dealership, and after maybe 3 tanks of fuel, I'm noticing a pattern. In normal driving mode, I'm now getting about 3mpg less fuel "economy" than I did before the service. Eco mode is not impacted as much - maybe 1mpg, maybe it's the same.

From what I can tell from the 5k checklist, that shouldn't happen - unless them bumping tire pressures a few PSI from 36 to 39 would have that kind of impact, which doesn't make sense to me. I called the service manager at my dealership to confirm also.

Has anybody else had this happen?

Could be that I just got unlucky with timing and we got higher ethanol gas or something, I guess?

 

Increasing tire pressure would result in better mpg, not worse. It lowers the rolling resistance as you would have a smaller contact patch from your tire. Were any software updates done during the service? Is it hot where you're and you're using the remote start more?

 

Right, I expected a mpg or two better from tire pressure bumps.

No software updates. That's what I was specifically asking the shop about - a change to the fuel map or something.

It's been hotter, yeah, and therefore likely A/C more, but not using remote start.

 

Using AC now versus not before would certainly account for a 3 mpg drop, especially if its city driving. Highway, maybe not so much.

 

Which is odd to me seeing as the AC in the 22 is less than stellar. I would gladly take a 3mpg drop right now if it actually made the AC blow colder and more "robust." So far, the AC is the only thing I miss about my previous Tundra.

 

Seems like AC is the biggest thing that suffers in the name of so called progress. AC in all my older cars were better than in my 2021. Although it is adequate for SoCal even, it just doesnt give me frostbite like the AC's from 20 years ago.

 

anyone else notice your AC blows cold, like actual AC cold air even you just have the blower on and the AC button is off?

 

Do you still have it set to "Max AC"? In my 21, if you use the max ac setting it automatically turns the AC on, maybe its the same for you except the light isnt on?

 

Mine blows cold air but it's not even close to my previous Tundra. That's in every drive mode, every button combo, AC selected, unselected, check on for Auto AC in the vehicle options, and with recirculate on. It takes 15-20 mins of driving before I feel like its cooled the interior of my truck off and I'm comfortable. My 2014 took a few minutes before I was like "shit man, ok! calm down."

 

It is an option in the vehicle settings you access on the multimedia display. Mine is set to turn AC on when it's in Auto mode. There is no "Max AC" like previous.

 

fancy shmancy lol

 

Eco mode turns on HVAC Eco mode too so AC blows weaker. Just set the temp lower. 68 is plenty cold for me in 80-90 F socal heat.

 

Yep, tracking. I don't use eco mode at all. Mine is set to low and I've tried 60 as well. Doesn't work like the old truck. Dealer said it was operating correctly, so I have to live with it.

 

might need to get some heavy tinted ceramic tint and some clear ceramic windshield film to help it out some.

 

That's on the list. My left arm got sunburned through the window on a 3200 mile road trip from Kansas to Arizona, through Texas then back to Kansas. That is not supposed to happen based on UVB blocking film that is supposed to be in car windows. But I don't know how else my left arm got a light burn and the rest of me was perfectly fine.

 

Is it possible the dealer updated the PCM when it was on the lift? I feel like that could be a pretty high possibility with a brand new design thats only been out 6 months or so. They are probably sending out updates constantly.

High ethanol gas should not be an issue on these engines. If anything, it should help. They run such a high compression ratio in addition to boost that anything which would help ignition timing(such as the cooling effect of ethanol) should help improve things. It literally runs a higher compression ratio than the 5.7L despite also making 15 psi of boost.

 

Ooooh, I didn't know this and always found it odd that Auto didn't turn on AC by default.

 

They claim not - just torquing and checking bolts, checking the torque on the hanger for the rear axle that was a recall, etc. Nothing engine related.

 

Maybe more ethanol, maybe more AC use, maybe heat soak and lower radiator efficiency causing the engine driven fan to clutch in more and run. Plus higher temp ambient air temps usually do not help turbocharged engines perform to their best potential. I've noticed that before with previously owned turbocharged vehicles. I notice it at work with the big medium speed diesels on the locomotives too. The high intake air temps limit power a bit, and seem to dull throttle response because the air density is lower. Sadly not low enough to reduce wind resistance of the vehicle to any meaningful degree though.

Might be a combination of all of the above, I usually expect to get better fuel economy in the spring, summer, and fall than the dead of winter but when it gets really really hot none of my vehicles seem to like it much.

 

I’ve seen some posts about weak AC and having low refrigerant charge but I can’t remember if it was here or another forum. Might want to get that check if you have time. Maybe the dealer checked.

 

I would think hotter temperatures excess of mid 90's like it is here would affect fuel mileage a little. Engine typically run better with cooler air going in.

 

I watched a YouTube video the other day, which showed there is a setting in the infotainment screen. That while on try’s to blend the AC cooling. Once turned off it appears that the AC has gotten colder. If I can find the video again I’ll link it

 

Yes, see this as well. Have to select AC then turn off.