Cruise control, is this normal?

2019 SR access cab, 4 banger, no major upgrades, I went up to 265 from the 245s it came stock with on TRD rims I bought. Im about to hit 88K on the mileage. My question is I do a lot of long distance driving for work and pleasure. I've noticed that with the cruise control on, the RPMs are always much higher holding a speed than if I do it manually, which I know has to be affecting my MPG. Is this normal for these trucks and if so why or is this an issue and how can I troubleshoot it...

Thanks in advance

 

On cruise, with even slightly larger tires, the transmission can be very reluctant to upshift to 6th, especially with a 4banger. Even the slightest uphill grade. There is something in the fueling/shifting tables for the cruise that is different than when you are on the pedal.

edit: Headwinds will do it also. Depending on what pressure you're running now, as little as +2 psi can help, though it is very minor help.

 

There's definitely something different when using cruise control. Every once in a while it holds a low gear way too long after cresting over a small hill.

 

There isn't enough information provided to give you an accurate answer; when you say you went from tires with a 245 section width to a 265 section width, that tells us the new tires are about 20mm wider, however, what we don't know is the sidewall height as expressed as a percentage of the section width. I believe the original tire size for your Tacoma are 245/75 R16 and if you went to a 265/70 R16 tire, then the diameter didn't change and there should be no impact on your engine RPMs at any given speed. However, if you kept the section width percentage at 75 (instead of dropping down to 70), then your tires are a larger diameter, and this will impact engine RPM as well as your speedometer and odometer (both will read below actual speed and distance traveled).

 

Apparently, you didn't read the post at all as neither the issue nor the answer has anything to do with the tires. I just listed that as a baseline of items. The issue is with the Cruise control. The engine holds a higher RPM when engaged than when disengaged, if I manually hold the same speed. I'm not stopping the truck and swapping out the tires when I disengage the cruise control, they are a constant in both scenarios.

 

Apparently, you don’t know how vehicles and overall gearing work. Your issue is not with your cruise control the issues with the gearing of your truck and the lack of power of the four-cylinder. Your tire change increase the drag because it’s slightly erase the truck. You effectively raise the overall gear ratio, thus decreasing the torque output of the engine and drive line.

so to put it simply, your tire size change has made it harder for your truck to drive will say 75 and six gear. So, it’s not in sixth but it’s in fifth that’s why your RPMs are higher.

If you want it the way it was change your tires or re-gear your truck.

 

The shift map is different with cruise control. Even the tunes like OTT can't change it apparently. Not much you can do except to drive slower. Most mods that make your truck look cooler (wider tires, larger tires, higher lift) worsen fuel consumption.

 

OK, that makes more sense than saying I didn't give enough info as ....obviously I did.

 

Actually you didn't. Why? Because you didn't list the aspect ratio of your new tires and as such, the rest of us are speculating as to what tires you actually put on your truck.

 

No……you really left out some rather important details