TBI to MPFI swap questions

[JeepsAndGuns]

Ok, time is nearing and I have a few questions about the needed bin mods.
I got the TBI to MPFI zip file I found on this site. I have preformed the required pcm and memcal mods, those were the easy parts.
One thing the zip file mentioned was the "injector offset Vs battery voltage" needs to match the injectors your using. It says if your using stock pfi injectors, to use the setting for it, and if your using aftermarket ones, to contact the manufacturer. It also says you can have your injectors tested. I have no clue who can do this.
Well I am not using stock chevy or aftermarket injectors. So just how improtant is this? Could I use the settings from a simillar sized gm injector and be close enough to be ok? This is not a daily driver, it doesnt have to run absoulty perfect. Its a old jeep with modern fuel injection.
The injectors I am using (if it matters) are the bosh 0280155703. They are the 4 hole ev6 style, and flow 238cc @ 3 bar (roughly 22.6 lbs/hr @ 43.5 psi). I am gonna be running them (to start out with) 40 PSI, witch should put them at roughly 21.73 lbs/hr. They are 12.5 ohm injectors.

I have another zip file that was simply titled "PFI memcal mod" In that zip file there was a $0E 7.4 PFI bin. I loaded it up and compared it to my tbi bin and the "injector offset Vs battery voltage" was exactly the same on both bins. So it appears whoever made that bin, did not change this. That is what makes me wonder.

Now back to the TBI to MPFI zip file, there is a "MPFI definitions v4.xls" file. It has a flags, constants, and tables sections to it, and appears to have all the things you need to change. Only one I dont know about, is on the constants and tables tabs there is a "conversion tab". What is all this data? Is this changes to the ADX file I need to make?

[gregs78cam]

"MPFI definitions v4.xls" Looks like it just tells you what things you need to set in the bin to run in PFI. If you are using 93V8S10's "Advanced$0E" suite of files then these xdf parameters should already be setup. Just need to make sure everything is entered correctly

[93V8S10]

Here is a thread discussing the offset table:
http://www.fullsizechevy.com/forum/g...ery-volts.html
The best way would be to have your injectors tested, but if that's not possible, then take a guess and hope for the best. You can always experiment with different settings latter. There's noting about this that going to keep you from getting the jeep running.

Ya, your xdf is already set-up, you just need to make the bin changes.

[JeepsAndGuns]

Ya, your xdf is already set-up, you just need to make the bin changes.

Sweet, thats what I wanted to know.

I read through most of the first page but its all way over my head.
The "pfi" bin I looked at had the same injector offset vs battery as my current bin, so do I just leave it as is? Or does someone have some I can enter in to get me "close enough"?

[93V8S10]

Unless you wind-up with a problem, then I would say that one wrong offset is just as good as another wrong offset, so stay with what you've got.

I wish I could explain the importance of the offset table, but I just bairly understand it myself, and its been a long time since I was trying.

[1project2many]

The injectors are electromagnetic devices. When the voltage changes, the injectors respond in a different way. Lower voltage means the injectors take longer overall to open. Higher voltage means the injectors respond quickly. So if the VE table currently requires 5 ms injector on time, and the injector takes .01 ms to open at 14 volts, then you've got to command 5.01 ms of injector on time to get 5.0 ms of fuel delivery. Now if voltage drops for some reason, say all the electrical accessories are on, and system voltage drops to 12v from 14, the injector may require .06 ms to open. With no voltage correction this means you've lost .05ms of fuel and the system will be slightly lean until INT / BLM can catch up. But with a good set of voltage corrections the extra time is added to the BPW value so the amount of fuel delivered by the injector remains unchanged.

This can get really obvious in a car where the voltage drops near idle. It's harder to tune, the VE seems all over the place, and each time you think you've got it tuned a small drive will change everything. The solution is to tune the voltage corrections.

If you don't have voltage corrections then no worries, they're easy to work out. Set all numbers in the voltage correction table to zero. Idle the engine (fully warmed up) and confirm about 14V on ALDL data. It's possible to connect a battery charger while the engine's running to increase system voltage at idle. Adjust VE so your INT and BLM are very close to 128 at idle. Disconnect the alternator and remove the battery charger (if used) so system voltage starts to drop. Watch INT. It will start to increase. As the system voltage approaches an entry in the voltage correction table, increase that number so INT moves back to zero. System voltage will continue to drop and you can keep adjusting the table entries in the correction table to bring INT and BLM in line.

The beauty of doing this is it takes into account the behavior of the entire system, not just the injectors, as system voltage drops. Once this table is set up there's no need to mess with it again unless you make changes to the injector wiring or change the injectors.

[JeepsAndGuns]

Good info! I think I understand it now.
Thanks