Well I got my 8.1L injectors installed today and I think I got the tune at least in the ballpark for them. Tune and scan attached if anyone wants to look and comment. Tune is OLSD and PE was disabled so I could verify if my IFR was giving me the correct AFR. I copies the injector data from a 2002 8.1L and then had to up the IFR 5% to get my AFR right.

 

Anyone have any input on this?? Truck runs fine but now the AFR is all over the place in OLSD as where it was nice and steady with the stock injectors. I figured this would be a straight forward copy and past settings from an 8.1L tune. There has to be something that I am missing. Also I guess I upped the IFR about 2.2% not 5% from 29.95 to 30.63 it was way rich with the stock 8.1L settings. I realize I may have to readjust the VE table a little but I would like to make sure I have the injector settings correct first.

 

I know there are some people here that have or are using these.... Does no one have any input on the correct way to tune for these??

 

must be a secret??

 

maybe a bad injector pumping more fuel than other..

 

Most guys just copy/paste and retune the VE. This works but I see what your trying to do. If your VE was fine with your stock injectors you shoud not need to make correction to your VE if you have the correct data in there, But its the best data we have. You could try the differnent offset tabes, pulse adder etc... from your stock, pre 04 8.1 and 04+ 8.1 tunes and see what gets you closest. Let us know what you find out.

 

It runs fine so I don't think that is the problem. The afr is just not as consistant as it was.
This is the direction I am heading at this point. After hours of searching, reading and a few hours of making my own adjustments it seems there really is no "right" way to do this (at least without spending a bunch of money). It would be nice if we had a way to easily get all the correct injector offset data, but it appears that the injectors mfrs. don't even bother to map this data out on their own injectors (or if they do they don't like to share). It appears that GM doesn't even really know what the correct offset values are after looking at different years of stock tunes. A 2002 and a 2004 are way different. I realize that one is a return system and one is returnless, but I see no reason the offset table should be affected by that. I'll make it work.

 

if this is the case, contact me. ill do w/e it takes to take care of it bud... id hate to see something like that happen to something i sold someone

 

Much appreciated, but I think the injectors are fine. As I said it starts and runs fine. I guess I'm just learning the truth of what "tuning" is really all about. While it would be nice if all of the tables, especially in the stock form, were all "correct" it isn't really the case. They are more just what works, so I think all we can really do is get things close with what info we can get and adjust what we know how to make things work! Of course the more money and time one can spend on each situation the better data that can be achieved, but I'm to lazy and broke for that...

So my AFR is not completely whack just a little unstable in OLSD. I am in the process of redoing the VE table now and I think that will settle it down.

 

That would make a big difference though. With the 04s, the differential pressure is constantly changing, causing the injector dynamics to change. EG, it takes longer for the injector to open when the differential pressure is higher.