Correct IFR tables for LS3/LS7 injectors in Gen III

[mr.prick]

Those are direct links from Holden Crazy so I can only assume they are legit.
You can look at any LS1 vehicle from the same years (2001+)
and see different values, the hardware is the same.
"Improved calibration" ......maybe.

that's a Greg question if I ever seen one... Maestro?

Was this meant to be an insult?

My theory is the injectors need to be manipulated for the vehicle they are installed in and one set of values will not work in all vehicles.
The .tuns linked seem to support that, provided they are legit.

[redhardsupra]

Was this meant to be an insult?

not at all, when it comes to explanations of why would OEM do something, Greg is a fountainhead of information

[bink]

What a great thread! Thanks for all the great info, guys.

[eficalibrator]

I'd like to know why 2 different vehicles with the same fuel injectors have different offsets & IFR.

...or just an improved calibration.
that's a Greg question if I ever seen one... Maestro?

With the caveat that they actually ARE stock files:

It's no secret that automakers routinely update calibrations even in service long after the initial vehicle release. Further, if one vehicle platform was released later than the other, it's very likely that the OEM had an update to the injector data from either the supplier or internal fuel lab in the mean time. Case in point: look at the LS7 injector data between the original release and now. (This is also the same injector used on LS3 in both Camaro and Corvette) They've learned more about these injectors over the years and refined the ECU calibration data based on a larger statistical sample. The changes are subtle, but I'd still prefer the latest iteration if possible.

[SweetS10V8]

I dropped in all the calibrations and my truck wouldnt start, sounded like I had no spark all the sudden. I had to go to clear flood mode to get it to do anything, telling me it was getting so much fuel it couldnt light it off. WHen it did start for a second, black smoke just rolled out the exahust. :(

When I get some free time Im going to change one table at a time and see if it was any specific part that made it not work. My tune couldnt be that far off could it?????

[WHYTRYZ06]

I dropped in all the calibrations and my truck wouldnt start, sounded like I had no spark all the sudden. I had to go to clear flood mode to get it to do anything, telling me it was getting so much fuel it couldnt light it off. WHen it did start for a second, black smoke just rolled out the exahust. :(

When I get some free time Im going to change one table at a time and see if it was any specific part that made it not work. My tune couldnt be that far off could it?????

I could be but, my thinking is the injector tables should tuned 1st before the car? idk i could be wrong....

Ima do mine today w/ marcins spreadsheet and ill report back...

[redhardsupra]

yes, injectors, and all other 'hardware' changes are the first step. there's some reading for you:

http://redhardsupra.blogspot.com/200...-bad-tune.html

http://redhardsupra.blogspot.com/200...ne-part-2.html

[Aloicious]

not to veer off course too much, but while on the subject of the voltage vs manvac offsets, I've got a question.

On a return style fueling system with a boost/vacuum referenced regulator, I have heard that there should be no slope across the varied vacuum rows (i.e. each cell in a specific column are all identical). I'm sure where ever I heard this, someone is making a connection with the IFR table which should be flat and unchanged between varied manvac cells (as opposed to sloped with returnless fueling systems).

however, the more I think about it, I wonder if that is correct. wouldn't greater manifold vacuum (regardless of what fuel pressure at the injector may be) inflict greater forces on the injector pintle (or disc or whatever) causing it to be more apt to stay closed, i.e. as manvac increases, there should be some slight increases in the actual offset to overcome these forces? if my explaination makes any sense.

[redhardsupra]

that's completely on topic actually.

you are correct, if your system keeps delta pressure constant, despite changes in MANVAC, then yes, you need to have your voltage offsets values constant across all MANVAC values. this tells the ecu that MANVAC values do not affect your voltage offsets. normally IFR is tied to MANVAC through Bernoulli's equation. with boost reference, you break that connection. delta pressure across the injector is kept constant, thus everything that depends on that delta pressure is 'disjointed' from it.

[mr.prick]

As battery voltage varies, the injector pulse widths are adjusted by this much to compensate for the changes in the opening and closing times.

How are the values in {B3701} applied?
Are they added like the small pulse values or subtracted?