Start of Injection Delay
 

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!

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.

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.

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.

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). :howdy: 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. :cool:

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!

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. :2thumbs:

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.

So basically the higher the number(ms?) the more advanced the SOI will be? Or am I backwards, seems like the higher the delay more advanced timing is needed to compensate for it? :shrug:

Dave,


Bill and I had a discussion a few months ago about SOI Delay and there's a reason he wanted to talk me through it on the phone....it's complicated but not really at the same time.

It's Ford's way of compensating for the mechanical and electrical delays in the injectors at different oil temperatures and injection pressures.

The reason it makes sense to change this map is because for regular injection timing, you've simply got a map based on RPM and MFD. That's ok but there is no temperature compensation for the injection timing (save for the SOI vs. EOT but that's a fixed adder) except for the SOI Delay map.

The higher the value, the more the PCM is going to compensate and the more advance you'll see. It is time based (in milliseconds) so there is an obvious injection timing advance going on at higher RPM since time is fixed and RPM is not. See where I'm going with this?

Just came back here to re-read this thread and I think there is a few posts that are missing.

For an "all out" program would you be better off setting this at a low number across the board?

Like the actual delay at full temp, which I guess will be around or less than 1ms. Of course the program would ONLY be used at full operating temp.Would this add a timing safety net?

Personally for my own programming I usually only alter this map by a half a millisecond or so at the most....and it's never at the higher ICP levels (high load).

You will see that most of the time in aftermarket tuning, the higher the ICP, the higher the delay is set. There are a couple of reasons for this, the biggest being that the amount of fuel being injected is higher for a higher injection pressure. By programming in an advanced SOI based on load and RPM (basically higher ICP and higher RPM), the burn is hopefully initiated sooner and it keeps the fuel from burning too much past TDC.

The nice thing about the delay map is that it is based on EOT. My programming will leave the stock delay at low temperatures (below about 120F) and at high temperatures (above about 240F). I usually incorporate the same temperature changes in the PW multiplier map too.

If you're worried about any effects due to a time-based SOI map, then it's best to leave the map alone.