My 03 Suburban has a 5.3 with 250k and I need more torque for towing. I started down the path of swapping with an LQ4 and my research on this site leads me to believe as long as I have a Gen III swap I don't have to mess with harness/ECU changes. The simple motor swap turned into me taking motor to my machine shop for some work and now I have a Brian Tooley Stage 2 truck cam, as well as TBSS intake and LS6 heads I am going with. Starting to wonder if these significant changes are going to change the simplicity of the swap. I know I will need to get a tune when the new motor is in but I'm looking for assurance it will run and not require other modifications. Any other things to consider I haven't even thought of yet? I don't need another poorly planned project that turns into a nightmare, especially for my daily.

 

As long as the nuts and bolts items are all good, it should be plug, tune, and play.

 

As long as you stayed with a 24/1 setup, your fine. If you got a newer 58x crank 4x cam, well then there's going to be a little more to it.

 

great thank you. Assuming will need a tune as well. Currently a flex fuel truck with the 5.3. Can it remain flex fuel after tune? Lots of cheap E85 here in Colorado Springs.

 

Yep, I would be sure your injections are flex capable.

 

Verify your planned injectors will fit your rail/intake, and the wiring clips are the same. (I have a 6.0 LQ4 in my GMC, switched from truck intake to TBSS.... the TBSS needs LS2 injectors & TBSS rail, and has a different electrical connector).

Make sure the fuel connections are the same for supply and return

Make sure your new throttle body works with TBSS.. likely you have a 3 bolt, TBSS is 4 bolt with no provision for a throttle cable.