You're right

Here's a screenshot of the stock tune from the truck the injectors came out of.

 

How does one explain this screen shot from a 04 FF tune?

 

Wow, I guess that there are two different flex fuel systmes out there.
Is that screen shot from a 4.8 or 5.3?
My response is based on an 06 5.3

 

Hey KB, that's weird that it says 33 across the board. For sure, the injectors I have aren't 33, it looks like they're 35.4lbs/hour. This is a screenshot of the stock tune from my truck. It's a '06 5.3 LM7

 

Just for ***** and giggles I pulled up a 04 Tahoe L59 tune and it's the same as what kb has. Here's the SS:

 

I wonder if It has to do with returnless fuel system.

 

Ya, I don't really know what the heck the deal is, but the couple 04 return FF tunes I have (including the one I put in my dads 72 have 33 in the IFR table, but if that's the table out of the truck they came out of, then that must be what they are

 

Yeah I guess... this is really confusing haha. I've never seen a IFR table like that until now. I wonder if the same injector p/n flows differently under a different fuel system. It definitely will with changed fuel pressure.

BTW, just checked out ACDelco's site and they use the same flex fuel injector for a broad range of vehicles ( ACDelco 217-1626 ). The injector for the '04 tahoe is the same as the '05 avalanche. I have a feeling that it's the fuel system.

 

If the IFR table has the same value in the entire table, that means it is a return-style based system.

 

returnless systems run higher fuel pressure. so the flow rates would be different in the pcm.