End of Injector Pulse.

General Tuning Questions And Discussions
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Re: End of Injector Pulse.

Postby Ken » Wed Sep 23, 2020 12:11 am

kojab wrote:Ken what happened to your latest post ???

Seeing that the topic had never been discussed here before, I figured it probably wouldn't spark an interest in the matter and ditched it.

I'll post it again I guess.

Been fiddling with the hsv tune in my WH for some time now, attempting to sharpen the throttle response transitioning through the 2000 rpm mark at various throttle openings, timing, mixture, VE or inj timing, couldn't give me what I was looking for, so I ventured into other areas that I'd found within the EFI live options, one which sparked an interest was the impact factor, which is stated as "Defines the fraction of fuel that will remain on the intake port wall per injection."
After adding this entry to my xdf and studying the different settings in the various factory tunes I've collected, and actually making the gains I was looking for at the 2000 rpm mark, I'm convinced it's going to be another setting I'll need to utilize whenever I do my next tune, (my sons car, motors getting rebuilt now).
I've had to revert some of the VE table changes in the 2000 range since altering this particular part of the tune.
The induction reversion noise was always louder around the 2000 rpm range, now no longer the case.

What I've seen in some of the factory tunes had me thinking that it was an under utilised part of the tune for some time, then somewhere between 2002-2003, attention was given to the entry, and all incremental options were plotted, not just a few blocks of numbers dumped into the setting.
Since the setting changes the amount of fuel that remains on the intake port wall per injection, my understanding of how that may be controlled is through varying the injection timing, and was wondering if Kojab had any insight into whether or not that was the case.

Here's some pics I'd made of the various 12225074 OS binaries..

2002_Clubby.PNG
2002_Clubby.PNG (65.79 KiB) Viewed 293 times


Checking that my xdf setting shows me the same as in EFI Live.
2002_Clubby_EFIlive.PNG


260kw_Clubby.PNG
260kw_Clubby.PNG (65.28 KiB) Viewed 293 times


Then from around 2003, the changes were incremental, not blocks of numbers.
STD_VY_Auto.PNG
STD_VY_Auto.PNG (69.2 KiB) Viewed 293 times

WK_Statesman.PNG
WK_Statesman.PNG (70.01 KiB) Viewed 293 times

285kw_Clubby.PNG
285kw_Clubby.PNG (70.67 KiB) Viewed 293 times

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Re: End of Injector Pulse.

Postby antus » Wed Sep 23, 2020 1:14 pm

I have not gone to anything like the detail you have but I really enjoy reading about your findings. I have noticed 04 tunes are noticeably improved over 01-03. My mate had a 03 VY SS and putting the 04 tune on it solved a flat spot he reported at the top of 3rd. It a no brainier to swap to an 04 calibration then go from there. Its interesting to see these tables.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: End of Injector Pulse.

Postby Ken » Sat Sep 26, 2020 12:10 pm

antus wrote:I have not gone to anything like the detail you have but I really enjoy reading about your findings. I have noticed 04 tunes are noticeably improved over 01-03. My mate had a 03 VY SS and putting the 04 tune on it solved a flat spot he reported at the top of 3rd. It a no brainier to swap to an 04 calibration then go from there. Its interesting to see these tables.

Thanks..

I always wondered why the LS1 injection timing would be set at a constant reference point when the crank speed would alter the time at which it would be most effective at completing an efficient cylinder fill, especially seeing that the LS2 and later had an injection timing baseline setting, and then another setting for offsetting the baseline based on the changing RPM.
LS2.PNG


I could be wrong of course with the reference to the setting changing Inj Timing, though seems to make sense from the way I'm seeing the picture at the moment.
I see in the LS2 tunes it references intake valve temp not coolant to reference the impact factor, along with other settings like wall wetting asymetry factor, plus the evaporation factor has an extended setting referencing rpm.

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Re: End of Injector Pulse.

Postby Ken » Fri Oct 02, 2020 2:21 pm

So further research on the impact factor setting leads me to believe that the injection timing isn't the altering factor in the wall wetting after all, the ratio of fuel varies from the start to the finish of each injector pulse is how the wall wetting is altered.

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