New silverado 5.3 gas mileage question?

[Samson521]

Turn AFM off with a tune

 

You telling me i have to go to the dealer and have them turn it off ? any way i can do it myself?

[txab]

Turn AFM off with a tune

 

You telling me i have to go to the dealer and have them turn it off ? any way i can do it myself?

 

Dealer will not turn AFM off. You'll need to get an aftermarket tune.

[Samson521]

ok.. thanks txab. aftermarket tune like in blackbear tune..

[MedicPilot]

Ok, the big difference is not the engine, It is the transmission. The 5.3L W/T, LT, LS all have the 4speed (6speed is optional, $$). The LTZ has the 6 speed standard, which is rated at 21mpg hwy(I average closer to 19). I test drive a dozen of these trucks before buying my new one a few months ago. I ended up getting the LTZ just for the 6speed, the rest of the options were great, but the 6speed with Manual override was what I needed. The 4.8/5.3 make less of a difference, than the 4spd/6spd transmission.

[joshw1303]

Wonder if they put a 6 spd auto on the 4.8, what mpg you get.

[music]

What's interesting is that I always get over 19 (usually ~20) on longer (over an hour) highway trips, and that's w/ the 4-spd/3.73. I'm pretty convinced that some trucks do a lot better w/ the AFM than others, but I don't see how AFM can help the 6-spd trucks as well as it does the 4-spds. Generally, 4-spd trucks pull higher rpms on the highway, so they have the "extra" torque to engage and hold AFM for longer periods. I was surprised that GM kept AFM enabled on the 6-spd trucks.