Injector PWs

[eboggs_jkvl]

If my goal is to allow the injectors to have a smaller PW at their disposal And I drop the Minimum IPW to .500 and the Default Minimum PW to .500, wouldn't I also need to work on B4005 "Small Pulse Adjust" and have it add no time from .500 up to 1.000? I would imagine that the values from 0 to .49 would need to range from 0 (.500) to .499 (.001). If I don't mess with the 4005 table, then my injectors will never have the opportunity of getting to .50 as 4005 adds milliseconds to values between .500 and 1.0 to make it sum 1.0 as the value.

Right? Wrong? Go away fool, this question is dumb.


Elmer

[eboggs_jkvl]

So, I targeted .85 as the minimum IPW

4005 looks like this

LABELS Small Pulse Adjust (Milliseconds)
Milliseconds Value
0.000 0.850000
0.061 0.789000
0.122 0.728000
0.182 0.668000
0.243 0.607000
0.304 0.546000
0.365 0.485000
0.426 0.424000
0.486 0.363000
0.547 0.303000
0.608 0.242000
0.669 0.181000
0.729 0.121000
0.790 0.061000
0.851 0.000000
0.912 0.000000
0.973 0.000000
1.033 0.000000
1.094 0.000000
1.155 0.000000
1.216 0.000000
1.277 0.000000
1.337 0.000000
1.398 0.000000
1.459 0.000000
1.520 0.000000
1.581 0.000000
1.641 0.000000
1.702 0.000000
1.763 0.000000
1.824 0.000000
1.884 0.000000
1.945 0.000000
2.006 0.000000
2.067 0.000000
2.128 0.000000
2.188 0.000000
2.249 0.000000
2.310 0.000000
2.371 0.000000
2.432 0.000000
2.492 0.000000
2.553 0.000000
2.614 0.000000
2.675 0.000000
2.736 0.000000
2.796 0.000000
2.857 0.000000
2.918 0.000000
2.979 0.000000
3.040 0.000000
3.100 0.000000
3.161 0.000000
3.222 0.000000
3.283 0.000000
3.343 0.000000
3.404 0.000000
3.465 0.000000
3.526 0.000000
3.587 0.000000
3.647 0.000000
3.708 0.000000
3.769 0.000000
3.830 0.000000
3.891 0.000000
3.951 0.000000
4.012 0.000000

Min IPW is set to .85
Default Minimum PW is set to .85

If my logic is correct, the Injectors can now drop to .85 milliseconds.

[dfe1]

Right? Wrong? Go away fool, this question is dumb.


Elmer
This sounds like a question from an old person.

[eboggs_jkvl]

Well, that doesn't seem to be a helpful damn answer.

[dfe1]

Well, that doesn't seem to be a helpful damn answer. I know, but I just couln't resist after some of your previous posts. I don't know where you're going with this, but you may get into some throttle transition problems with anything near your target IPW. Even when a system goes into DFCO, which essentially shuts off fuel flow, IPW is about .35 ms. The system knows when it comes out of DFCO so it knows how to adjust fuel flow to avoid stumbles and hesitation. But by all means, it's worth experimenting. Don't forget that you have to include some provision for injector opening and closing time. With a pulse width of .5 to .8 ms most of the available on time is consumed by the opening and closing cycles.

[eboggs_jkvl]

Someone tried to help me with my hot idle problem by, among other things, lowering the Minim IPW and the default minimum PW to .5 Ok, my logic says those won't be reached if the SPA is left alone. SO, did we want to reach there? I chickened out and compromised at .85 but the Purpose of changing those 2 without adjusting the SPA just defies my understanding. As far as I can see, changing those does nothing without adjusting the SPA. That's basically my question.

[hpcubed]

You are correct. There seems to be a bunch of redundency with the short pulse time limit. According to EFILive
"When a very short injector on time is commanded (between 0 - 4mS) the PCM will add the values in this table onto the injector on time."
Log IPW after you make changes and verify your results.

[white2001s10]

I'm curious to see the results as well. It sounds like an experiment that I'd do given a chance.

What's wrong with your hot idle by the way? perhaps there's an easy solution.

[eboggs_jkvl]

Hot idle hunts for idle. If I start it cold, first thing in the morning, it is perfect. Hits 1100 and walks down as the temp comes up and has a rock steady 850 when fully warmed up. Drive it, say to the store, do some shopping for an hour, come back and start it up, it hunts for idle. Drive it 100 yards, stop and it's rock steady at 850 again.

I've gone and found a 2002 LS6 Vette tune and copied it in to my tune. After doing this, the idle is better but it still wants to wiggle around but not as bad as it did.

The tables that I last emulated were 4403, 4307, 4308, 4315, 4321, 3702, 3703, 4003, 4004, and 4006.

Because I have a 98 PCM, I did a lot of copy and paste. The tune is a stock LS6 except for the injector rate. I'm running 60#ers

Right now, it's the best it's been since the new engine. It still wiggles on the hot start but not the big surge I was originally chasing. I gave up on running the injectors on smaller widths as it got self defeating as I went lower. My "fix" now is to hold the throttle open slightly and give the engine a chance to figure out what it needs to do. As I said, drive it 100 yards and the problem is gone.


Elmer

[white2001s10]

Drive it, say to the store, do some shopping for an hour, come back and start it up, it hunts for idle. Drive it 100 yards, stop and it's rock steady at 850 again.

There are several tables for after-start enrichment, and that sounds like the problem to me.
When you start cold, you're in the coolant corrected open-loop which adds a lot of fuel.
When you start warm, you are put immediately into after-start enrichment that decays at a rate specified in the tables. You can also adjust the amount of after-start enrichment.
When it's hunting, get an idea what the true AFR is doing and you'll know which way to go with those after-start tables.

I think there's a really good chance you're just getting WAY too much fuel during after-start with those big injectors.

I'll put it this way, 99% of the time you could get by with ZERO after-start enrichment fuel, so any significant amount is too much.

[eboggs_jkvl]

I found 3 tables.

3650 now set to .1
3628 now set to 1
3627 now set to 5

Let's see what that brings on hot starts.

Thanks

[eboggs_jkvl]

We may have solved the problem. Hot starts are 1 RPM drop to 550 or so and then it hits 850 and holds. I don't have to touch the throttle at all to hold idle. I think I'll leave it like this for a week and see if it learns and settles down even more.

E:)

[eboggs_jkvl]

Screen shot of the idle on a hot restart.

[white2001s10]

Great news.
unhooking the battery will encourage the idle learn to correct faster since it forgets all the old stuff.

[eboggs_jkvl]

When we Flash, don't we accomplish the same thing? The new flash removes all vestiges of "learned" information and restarts the process from scratch?

[white2001s10]

I use EFI-live and mine doesn't erase the idle learn when I flash.
Unhooking the battery definately does and you can tell the second you start it.
can't hurt to try.

I wish I was having as good luck with my fuel-cut problem.