TC Shudder…fixed. New problem arises..?

Hey all, wanted to see if anyone had ideas thoughts comments or experience related to the following.

2018 AT DCSB

TC shudder at 92k, dealer agrees and fixed under PT warranty. Cool.

02 sensor code two days later and subsequent drop from lifetime 17.5 mpg to current 15.5 mpg.

Dealer took it and said exhaust gasket was crimped. Fixed and ate the cost.

02 sensor code never came back. Cool.

I have no idea why my truck is still getting 15.5 mpg instead of 17.5 like it has for 8 years……

I thought o2 sensor code made sense because it was running rich but now that code is gone and suspected problem was gasket that was fixed, but mpg never returned to normal..?

thoughts anyone? Really don’t know what to make of this one.


Been using these forums since I bought truck, hundreds and hundreds of time. First time posting a problem. Thanks to all you regulars over the years!!!

 

Not that it means anything but has the rear diff oil ever been changed?

 

Could it be a coincidence and just be due to cold months? I see 10% drop in winter.

 

It has not.

 

I’ve always gotten 17.5 year round really and was again during this winter . The 2.0 mpg drop started right after TC was replaced.

I was even getting 17.5 while TC shudder was annihilating me between 20-40 mph, prior to the fix.

 

I’d swing by a valvoline and change the rear diff oil. I just replaced the driveshaft ujoints for a second time at 184k and they tightened up the driveline a lot. Maybe a touch more air in tires, too. New shocks… it never ends. Good luck!

 

thanks man. Appreciate it!

 

Did they pull the battery and the computer has to relearn everything all over again? Or pull it and let it relearn.

 

Idk, I was thinking that as well. Was considering re flashing with OVT and seeing if that would maybe fix it.