SLR88

Correct it’s a 5.3. And thanks for all the positive feedback..Like I mentioned it’s probably a non issue, I just need to understand I’m not pulling with my 6.6 anymore. And E the troll yahoo, I’m not sure your ridicule is welcomed in this forum.

Also, by the way, when it kicks in “passing gear” and increases the rpm’s, there’s no increase in speed...it’s all acceleration and no torque. Like it’s stuck..this it why I thought I was having issues with the AFM. I’m just wanting to rule out electronic and mapping issues before I accept that it’s all in my head after many years with my 6.6 diesel.

I appreciate your replies. It’s a 5.7 and I am referring to the AFM. Thanks for the correction. Also referring to down sizing to 255/55R18 I calculated tire size to be about 2” smaller. Not sure of the rear end gear size....Dropping cylinders I’m referring to AFM reducing cylinders. And this may be a non-issue other than a gas hog because like I said I just purchased this vehicle coming from a Chevy 6.6 3500HD dually and it is day and night difference. With that said I probably need to relearn how to drive a non diesel vehicle.

About to loose my religion.....Just purchased used 2015 GMC Sierra Denali 5.7 With 255/75R20’s Pulled a lightweight enclosed trailer and got 8-9 mpg. I could actually see needle move...Engine constantly jumped to 4,000 rpm on very slight inclines. I’m assuming I’m having cylinders drop???? Even when trailer switch is engaged.. If not DFM would changing to 18” tires help???? Thanks