18436572 Gen 1 firing order on 411 PCM

[APS]

Is there a way to change the firing order in the pcm to correct the banks for closed loop fueling?

Truck runs great in open loop. I just can't allow closed loop operation or the trims are all over the place.

[Eaglegoat]

Why would changing the firing order fix this problem? Tune/log?

[MikeOD]

Look at the injector bank select table in the injector data section. Compare it to data from a Vortech L31 van. Match up the injector wiring diagram to that of the van and assign the coil wiring in the same manner and closed loop will work great.

[MikeOD]

Why would changing the firing order fix this problem? Tune/log?

Because the LS1 firing order is 18726543 but the gen 1 firing order is 18436572... You cannot change the hard coded order that the wires fire, so to run a gen 1 with an LS1 PCM, your swap the wires for the coils and the injectors with 4 to 7 and 2 to 3.

The injectors are assigned to O2 sensors with the bank select table, 0 and 1 corresponds to bank 1 and bank 2, so in that table where you see ABCDEFGH, the numbers will be 01011010 for an LS1 and 01101001 for a gen 1 engine.

This is how GM did it with the L31 and the 411.

[APS]

Because the LS1 firing order is 18726543 but the gen 1 firing order is 18436572... You cannot change the hard coded order that the wires fire, so to run a gen 1 with an LS1 PCM, your swap the wires for the coils and the injectors with 4 to 7 and 2 to 3.

The injectors are assigned to O2 sensors with the bank select table, 0 and 1 corresponds to bank 1 and bank 2, so in that table where you see ABCDEFGH, the numbers will be 01011010 for an LS1 and 01101001 for a gen 1 engine.

This is how GM did it with the L31 and the 411.

I knew darn good and well what it looked like but sat there looking for it in the wrong place. DUH!

Thanks, Mike

[MikeOD]

No problem. Fuel trims working a little better now?

[APS]

No problem. Fuel trims working a little better now?

Yep all good.