Start of Injection Delay

[cleatus12r]

Here's a serious question, Bill.

The Start of Injection Delay has me a bit confused lately. For those that don't know, I started with Sniper Delta Force tuning software. Although it's a good tool, I picked up some...uh...."bad habits" with it because all I knew about fuel-related "tuning" (I use that word loosely.) was the injector pulse width map (called "table" in their software) and all I had to do was increase it in certain ICP ranges....VOILA! That's how THEY did it, so that's how I did it.

Well, tuning for EOT makes 150% more sense since just increasing the injector on-time kind of makes for excess fuel no matter if it's -50 or 300 degrees.

The injector delay is confusing to me. I wish I knew what the units were that I am changing (to somewhat mirror yours Bill because I trust what you're doing is right) depending on EOT and fuel rates. The other tuning I see has wildly fluctuating data compared to yours and some has no compensation whatsoever.


The SOI Delay Map in Delta Force (Farce??) is called "Injection Timing Adder for ICP vs. EOT" and the values given in the table are NOT related to the values in Minotaur's table. For reference, searching came up with this post:
http://dygytalworld.ehost-services13...6&postcount=37

What exactly IS the SOI Delay Map, why is it there, and how do you determine what values should be input?

Thanks for the help!

[cleatus12r]

The more reading and research I have done leads me to believe that the increased values I am seeing in aftermarket tuning shows an increase in delay. The PCM may then use these values to advance the SOI farther than the stock values in this map. On the other hand, the values of less than "1" will cause the PCM to calculate a later SOI than with the increased values that many happen to run.

If I'm not overstepping my bounds here, I'd like to ask why, when your tunes and the factory are decreasing the SOI delay value at higher ICP (which is understandable), a different tuner happens to be increasing his values.

There is a HUGE discrepancy between stock and higher HP tunes (which as the HP level goes up, so does the SOI delay). Again, I ask why?

Is there a problem with leaving the SOI Delay map with its stock values when tuning all other fuel/timing maps? By my thinking, it seems safer.

[Power Hungry]

Cody,

The detailed explanation for this is something more involved than my fingers actually have time for. The short explanation is that it is delay in milliseconds between the time the injector solenoid is energized and the time that fuel actually starts to spray out of the injector. If you compare Singles vs. Splits, you'll notice about a .2ms difference in this table which accounts for (among other things) the pilot shot. This is also why the table drops off the higher the ICP goes. More pressure, less delay. Being a time-based table, the higher the RPM, the more crank angle for a given time period.

When you have time, give me a shout and I'll be happy to get into a bit more detail.

Laterz.

[cleatus12r]

That's what I was thinking.....somehow I was drawn to the conclusion that the table was defined in ms but had no way to know.

But I'll call you and get some more information.

Actually, I will be home all day today because I'm back to a 4-day work week. I have to drive to town to pick up a few more things for this 7.3L IDI that I rebuilt for a guy (hoping to have it running today) and I will be back in time to call. Expect a call today between 1-2 PM your time.

[cleatus12r]

It was great talking to you again Bill. Somehow I always feel kind of special when we talk like old friends (who aren't really that old and who have never met). I'm getting excited since we're down to less than a month before SEMA. It'll be nice to put person-to-person faces with you and Corey's names.

In the grand scheme of things, it was nice of you to take the time to 'splain to me what that map does and how it relates to SOI.

Thanks a million!

[Power Hungry]

As Corey will tell you... "Bill has never met a stranger." I've always talked to people like old friends. Some may find that a bit unprofessional, but I think it's just a nice way to be. In the hustle and bustle world of today, people just don't seem to take the time to actually talk to people anymore. Of course, being a chatterbox has its drawbacks sometimes and I frequently have Corey reminding me that I have work to do. :whistle:

Corey and I are quite excited to be seeing you guys (Jack and Janet included) in Vegas and are glad that we could help out. We're gonna have a blast for sure.

Anyway, if there's anything else I can help with or any questions I can answer, I'm happy to make myself available.

Take care.