E38 vs E78 injector data

[blindsquirrel]

Here are two files, both are VIN 'G' L96 using injector # 12613412. I haz a confused.

2010 Yukon E38 L96 1GKZKREG0AR189018 (OS 12636005)(12613412).hpt
2012 Silverado E78 L96 1GC1KYEG1CF221580 (OS 12647731)(12613412).hpt

screenshot.03-05-2022 09.01.48.png

Short Pulse Adder tables are quite different. Both files, however, have identical Offset v Press v IGNV tables.

So what explains the difference in the IFR tables?

[BigTuner]

Interesting, maybe GM later found slight inaccuracies in their injector data?

[blindsquirrel]

2013 E38 keeps the same 50.9@408 as the 2010 E38...

2013 Express 3500 1GB0G2BG0D1165438 E38 L96 (OS 12654075)(12613412).hpt

My only guess is something like none of them use a FPCM but they have different base fuel pressures. Without a real-time rail pressure to use for the IFR calc, they adjusted the table to compensate for something like 62psi for the 52.2lb vs 58 for the 50.9. If you do the conversion that roughly works out.

[blindsquirrel]

Busted that theory... this one does have FPCM, and injector data is identical to the other E78s.

2017 Silverado E78A L96 1GC4KZCG6HF205677 (OS 12677353)(12613412).hpt