turbo 5.3 issues as going into boost

[Custom 68]

Hi all, I have been using HP tuners for quite a while but not nearly as knowledgeable as many on here. This is in my 68 C10. As I have worked on this I seem to have made things worse. I found a bad vacuum leak that I fixed, I am not sure if that was the start of my issues. Any input would be awesome. If I need to log differently I would appreciate any suggestions as well.
As I easily move into boost I feel a lot of stumble and it feels very flat. I am cautious to really lay into this without some direction.
Thanks a ton,
Dave

[blindsquirrel]

'Tuning' is, for the most part, collecting data, then applying that to the airflow model(s) to make commanded fueling match measured fueling. Your log shows it a full point leaner than commanded. Needs to be tuned, not fiddled with to see if it'll run better.

[Custom 68]

Thanks I understand. I will go and collect data and work on the VE table. I have read and understand what I need to do and have some tables setup in my scanner to make these percentage changes.
Thanks,
Dave

[blindsquirrel]

What injectors are those, and, you converted to a returnless fuel system? Let me guess - swap vehicle so Corvette filter/regulator thing?

If so... that filter will not flow enough through the return port to control the pressure with a pump big enough to feed 72lb injectors.

[Custom 68]

they are 60 lb-hr Deatschwerk injectors. I have the info I will need to find again but they came with all the info I copied in according to what I understood. It is a swap vehicle my 68 C10 swapped about 10 years ago and added the turbo recently, this is not my daily.
it is not a returnless system, I kept the return setup as originally on the 2002 5.3 so no corvette style filter system.
Thanks,
Dave
Let me find the injector data so I can post. That might help, I did drive it and collected more data, you are correct it is lean.

[Custom 68]

Here is what I have for data for the injectors. I have tried to do this as correct as I could.
again thanks,
Dave

[blindsquirrel]

The injector data in your file is entered as if it was a returnless system. Referenced/return uses the 0 kPa column data, pasted into every column all the way across, for both Injector Flow Rate and Offset vs Volts vs VAC.

This spreadsheet shows both versions, you should be able to spot how it works and what you should do when you can see both types right next to each other:
https://forum.hptuners.com/attachmen...3&d=1707139116

[Custom 68]

ahh ok, I will need to get my other computer with excel and sort that out and look at the file you sent.
You mention I should be able to spot the difference, what does a person look for? I had assumed (incorrectly) to use the one that had a varying output with the difference in pressure since the return system has the regulator on the fuel rail that varied the pressure depending on vacuum ( or lack there of). I didn't think there was any feedback to the returnless system? I probably changed it thinking I was making it correct.
I am sue that is pretty basic but I missed it thinking I understood it. I will make the change.
Dave

[gametech]

A boost and vacuum referenced return system keeps the effective pressure across the injectors static, hence the same numbers all the way across for your fuel injector flow settings. The returnless system as you correctly surmised, has no feedback, therefore as vacuum or boost varies, the effective pressure across the injectors changes, necessitating different flow rate numbers.

[blindsquirrel]

Look at the spreadsheet until you go "OH! THAT! I get it now." It shouldn't take that long for it to click.

[Custom 68]

ohhhh well that does make sense, I had read about the static pressures vs the injector pressures and those differentials but thought too deep.
thanks for the easy lesson, I will make the changes. Will this drastically throw my VE table off? Either way I have the confidence to just log the numbers and trust the "system" for the tuning.
Dave

[SiriusC1024]

Will this drastically throw my VE table off?

Yes.

[blindsquirrel]

Who knows, maybe it will make the VE better, seeing as how far off it was before.

[Custom 68]

This is information I was looking for, something I had done or an issue in the tune. I now know what I have done so I can move forward without wondering why things went off the rails.
I am back to my computer with Excel so I can see your file, it is obvious as yours gives the wording "returnless" and "manifold referenced" My excel file does not spell it out as clearly, I made an assumption and didn't research it any deeper.
To ensure I have this correct I need to keep my vacuum hose attached to the regulator as it is now to allow this to perform as expected?
Looking at the attachment you mentioned above to use the value at "0" kPa across all the columns on the flow and offsets.
I will make these changes and bet you are correct I may now be closer. One step forward, as I know how important the correct data is so I was happy I had the information however my error in how I interpreted (used) the data.
Thanks,
Dave

[blindsquirrel]

Yes, vacuum hose connected it uses the 0 kPa column all the way across. Vacuum hose removed it uses data like you had it before (sloped, increasing as manifold vacuum increases). Both assume 58 PSI - always 58 PSI all the time no matter what if 'returnless', and 58 PSI base (key on engine off, or idling with hose temporarily removed for testing/setting pressure) for 'return'.

[Custom 68]

perfect than you for the patience and lesson. I had confirmed my fuel pressure so all that is good, I had added a gage to make sure that wasn't the issue. Depending on time and weather I will report back as I get this dialed in.
Dave

[Custom 68]

Just a quick update, I did get all the correct injector information in my tune and made a run. Things are more stable as hoped, I collected quite a bit of data and applied it to this tune. I have not ran again but if this is closer as I expect I will post the new tune and log. For now I believe things are moving the right direction.
Dave