Manual shifting your auto for engine braking

[L31MaxExpress]

On a Vortec, is it the same (ignition timing retard) or is the fuelling interrupted?

GM cuts ignition timing as well as disables cylinders (cutting injectors) depending on how much torque reduction is called for.

 

[Scooterwrench]

Disables cylinders as in turning off spark and/or fuel?

 

[L31MaxExpress]

Disables cylinders as in turning off spark and/or fuel?

Cuts injectors off. If spark retard alone cannot limit the torque enough, it will cut individual cylinders. I altered that table to keep mine on all 8 all the time. The PCM also has a Desoot mode that cuts injectors to help clean the chambers out.

 

[Scooterwrench]

Cuts injectors off. If spark retard alone cannot limit the torque enough, it will cut individual cylinders. I altered that table to keep mine on all 8 all the time. The PCM also has a Desoot mode that cuts injectors to help clean the chambers out.

DFCO doesn't do that?

 

[L31MaxExpress]

DFCO doesn't do that?

It might help, but the GM Desoot mode runs when you first enter PE. It shows up as a lean wideband reading ~2 seconds into a WOT run. The engine is not actually lean, but the non firing cylinder pumps air into the exhaust (1 per crank rotation) and shows up as lean exhaust.

 

[revmatcher]

I downshift my 2023 Vette at every stopsign.

 

[NMNorsse]

My '88 K1500 has the 700R4 and its time to do a fluid/filter change. I use it mostly for hauling materials and towing with some occasional offroading. In the mountain west we spend a lot of time going up and down long grades. If you don't engine brake by down shifting the tranny you end up riding your brakes until you warp the rotors or they overheat and fade. So, engine braking is a practical necessity. While I've got the tranny apart I'm planning on putting in a TransGo 2-3 kit which keeps the fully auto function but allows you to hold 2 or 3 to any RPM. I think that'll be useful towing, offroading and engine braking.

Does anyone have any experience with that?