Correct IFR tables for LS3/LS7 injectors in Gen III

[SweetS10V8]

I have an 04 Silverado PCM and Ive swapped LS3 heads, intake, and injectors on my 6.0L (LQ9).

Ive been doing some AutoVE tuning just to get the hang of things. Ive got that down and my LTFT are 0-3% almost all the time.

Now I want to stop practicing and do it right, Ive read that its best to use a GM injector because GM did all the work with ALL the other setting besides flow rate. So I chose a stock injector specifically for that reason. I thought it would just be a "copy and paste" all of the tables, but they do not line up at all and some tables just dont exist. Im assuming its since the LS3 and LS7 cars use a different PCM.

How do I make sure my IFR tables are correct? Ive found stock tunes for LS3 and LS7 Vettes on holdencrazy but dont have the knowledge to swap/convert everything.

[SweetS10V8]

I used the spreadsheet I found on here to get my numbers in my tune. I just told the spreadsheet I had 41lb/hr injectors and copied and pasted the table.

[dfe1]

I have an 04 Silverado PCM and Ive swapped LS3 heads, intake, and injectors on my 6.0L (LQ9).

How do I make sure my IFR tables are correct? Ive found stock tunes for LS3 and LS7 Vettes on holdencrazy but dont have the knowledge to swap/convert everything.

The LS3/LS7 injectors are flow rated at 4-bar, the same as LS1/LS2 injectors. All you need to do is use the values in a file from a vehicle that uses the injectors you've selected. Couple of suggestions-- make sure the flow units are the same in both files-- either Imperial or metric, keep in mid that the IFR tables in Gen4 ECMs are referenced to "Delta MAP"-- the difference between Manifold Absolute Pressure (MAP) and fuel rail pressure. and-modified fuel system pressure. A Delta MAP of 400 kPa equates to 4bar of fuel pressure and 0 manifold vacuum so the value at 400kPa in a Gen4 file equate to the value at 0 in a Gen3 file. Note the flow rate table in both files is B4001.

[SweetS10V8]

All you need to do is use the values in a file from a vehicle that uses the injectors you've selected.

That was the plan until nothing matched up. Thats why I posted the differences under my injector folders in my tune ('04 Silverado) and the stock tune ('08 Vette) which has the exact injectors Im using.

keep in mid that the IFR tables in Gen4 ECMs are referenced to "Delta MAP"-- the difference between Manifold Absolute Pressure (MAP) and fuel rail pressure. and-modified fuel system pressure. A Delta MAP of 400 kPa equates to 4bar of fuel pressure and 0 manifold vacuum so the value at 400kPa in a Gen4 file equate to the value at 0 in a Gen3 file. Note the flow rate table in both files is B4001.

So i400kpa in gen IV = 0 in gen III? Thats great, but the helps me fill in one single input. How do I convert the rest?

What about the rest of my inputs under my injector file that dont line up with anyhting from the tune that uses the injectors Im running?

[Gelf VXR]

That was the plan until nothing matched up. Thats why I posted the differences under my injector folders in my tune ('04 Silverado) and the stock tune ('08 Vette) which has the exact injectors Im using.
So i400kpa in gen IV = 0 in gen III? Thats great, but the helps me fill in one single input. How do I convert the rest?

What about the rest of my inputs under my injector file that dont line up with anyhting from the tune that uses the injectors Im running?

Ive just done this


http://forum.efilive.com/showthread.php?t=11878

[dfe1]

That was the plan until nothing matched up. Thats why I posted the differences under my injector folders in my tune ('04 Silverado) and the stock tune ('08 Vette) which has the exact injectors Im using.

Things aren't going to match up exactly because, among other things, the voltage offsets are different between LS1 and LS3/LS7 style injectors. Don't worry about every number being exactly what you think it should. There are a number of factors that come into play, not the least of which is that even in a bone stock LS3 or LS7, the fuel trims are likely to be off a good bit. I can't remember the last time I saw a stock tune with long term trims that were consistently in the 0 to -5% range.

[joecar]

Expanding on what dfe1 said:

GenIII:
pressure difference across injector = FP + MANVAC
so then: IFR = R0 * sqrt((FP + MANVAC) / P0)
where: FP = fuel rail pressure = 58 psi = 4 bar = 400 kPa

GenIV:
pressure difference across injector = DELTAMAP
so then: IFR = R0 * sqrt(DELTAMAP / P0)
This is what Gelf did using the spreadsheet.

[joecar]

Expanding on what dfe1 said:

GenIII:
pressure difference across injector = FP + MANVAC
so then: IFR = R0 * sqrt((FP + MANVAC) / P0)
where: FP = fuel rail pressure = 58 psi = 4 bar = 400 kPa

GenIV:
pressure difference across injector = DELTAMAP
so then: IFR = R0 * sqrt(DELTAMAP / P0)
This is what Gelf did using the spreadsheet.

So it seems that DELTAMAP is the same as FP + MANVAC... they are both the pressure difference across any one injector.

This can be used to convert the vertical axises between the GenIV and GenIII B4001 tables...

OEM stock value of FP is 4 bar (58 psi, 400kPa):

  MANVAC  MANVAC+FP
  [kPa]    [kPa]
    0       400 <--- WOT
   10       410
   20       420
   30       430
   40       440
   50       450
   60       460 
   70       470 <--- idle (small cam)
   80       480

I need a sanity check, does that make any sense...?


So, in other words:
the GenIV B4001 cells between DELTAMAP 400 and 480 [kPa] correspond to
the GenIII B4001 cells between MANVAC 0 and 80 [kPa].


See the highlighted cells in the attached ZR1/LS9 B4001 table.

[5.7ute]

So it seems that DELTAMAP is the same as FP + MANVAC... they are both the pressure difference across any one injector.

This can be used to convert the vertical axises between the GenIV and GenIII B4001 tables...

OEM stock value of FP is 4 bar (58 psi, 400kPa):

  MANVAC  MANVAC+FP
  [kPa]    [kPa]
    0       400 <--- WOT
   10       410
   20       420
   30       430
   40       440
   50       450
   60       460 
   70       470 <--- idle (small cam)
   80       480

[FONT=Courier New]
I need a sanity check, does that make any sense...?

Consider yourself sane. lol.

[dfe1]

Consider yourself sane. lol.

I don't know, seems to be that's reaching a bit. The fact that Joecar can figure out these tables doesn't necessarily imply he's sane. After all, like the rest of us, he spends entirely too much time messing with cars.

I think part of the challenge to understanding these tables is the fact that almost every other manifold-oriented parameter is referenced to manifold pressure, as opposed to vacuum. One is simply the inverse of the other, but sometimes switching back and forth between two perspectives can be confusing. Back in the day, the common reference was manifold vacuum expressed as inches of Mercury. People who used to work with carburetors had to make the transition from thinking in terms of vacuum in inches of mercury to manifold pressure expressed in kPa. I've always found it easier to work with the terms of the relevant measurement units as opposed to trying to convert from one to another. You can't really get a handle on things until you learn to think in the units you're using.