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Thread: Did b9021 Injector Pulsewidth Ever Become available to 1mb PCM's?

  1. #1
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    Default Did b9021 Injector Pulsewidth Ever Become available to 1mb PCM's?

    Per supplied data for my injectors, I have:
    B4003 Min Injector Pulse Width set to 1.299mS
    B4004 Default Min Pulse Width set to 1.280mS
    B4005 Small Pulse Adjust are negligibly small values
    During deceleration, the Injector pulse width hits some mysterious floor at 1.66mS and drives my fuel mixture way rich. Its right on the cusp at idle and just a bit richer there than I'd like too.
    Upon searching, I found out that apparently EFILive is missing a seemingly crucial table (b9021?) which is responsible for this issue. Everything on this topic seemed to fizzle out around 2013-2014 time frame... I imagine there are quite a few big injector 1mb pcm's out there still struggling with getting their actual pulse width down to commanded during idle and especially deceleration. It seems like HPTuners has this "transient" injector limit but I prefer to use EFILive and really didn't want to buy another HPT VIN license for this car just for one silly thing.

    Does EFILive (or any 3rd party developers out there) have anything to help with this issue for my stock 12592618 OS (2005 cts-v)?
    If there is support for this functionality in a custom OS (0512000x I believe) I would be open to that too, just really feel like there has to be a solution to this very fundamental issue. Thanks!

  2. #2
    Forum tyhee Site Admin GMPX's Avatar
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    The last time EFILive actively worked on the LS1 PCM was 5 years ago and that was just to add in a parameter B3420 "Mimimum Injector Pulse Width", prior to that it was 2009 which was all the fuel dynamics tables.
    Most LS1 development is now being done via community tuning forums.
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


  3. #3
    Joe (Moderator) joecar's Avatar
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    See post #17 here: need-B9021-for-0125000

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    Quote Originally Posted by joecar View Post
    See post #17 here: need-B9021-for-0125000
    Ahh, sure enough, there it is, a cax for 12592618 OS! Somehow I missed that instance when I used the search for that number... it pulled up a LOT of results. Thanks for pointing me back in the right spot.

    And, thanks 5.7ute for supplying that

  5. #5
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    Well, just had a very interesting experience...
    The stock b9021 value was 0.988 and not knowing exactly how that was influencing the pulse width floor, I just reduced it by 20% to gauge the effects. I was still hitting the same 1.66 mS floor as before, however my fuel mixture in general seemed to be significantly and randomly affected...
    I just recently finished BMT spark timing calibration, then VE table calibration, then idle airflow/stabilization calibration, and then MAF calibration, all in open loop with serial WB. Just prior to changing b9021 my EQ ratio error "BEN" was consistently running around +/-2.5% error. With the only change being b9021 20% lower, I took the same route in very similar ambient conditions as I usually logged changes in and was watching my BEN min and max hitting .82 and 1.19 (+/- 19 to 18% error)!
    Am I trying to do this right, or is this actually being applied as a transient value in some way as its name applies? I'm not hitting anywhere near my min pulsewidth per b4003, 4, and 5 but maybe I need to try to lower those and see what happens...
    This is the same car though that I've observed some crazy things in, e.g. it changing the throttle cracker and follower application totally differently whether closed loop fueling is enabled or disabled

  6. #6
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    Quote Originally Posted by chevyspence View Post
    I'm not hitting anywhere near my min pulsewidth per b4003, 4, and 5 but maybe I need to try to lower those and see what happens...
    You are hitting your minimum pulsewidth. Lower those tables (b4003, 4, and 5) to the same value that you have in B9021.

  7. #7
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    You were right, sure enough, b4003, 4, and 5 were responsible for that floor I was hitting. So to me it seemed like b9021 really is a transient value and in my case did some screwy things, and putting it back to stock and lowering the b4003,4,5 tables did the trick nicely.
    I was trying to do a simple math "default min PW" (1.28) + "small pulse adjust" (0.077) = 1.357 at steady state should be my min achievable pulse width and it didn't seem like I was hitting that at 1.66, but that obviously didn't correlate and must be other factors at play behind the scenes. I guess the transient table must add some small amount too even at dead steady state or something. Is there something I was missing that you picked up on, or just knew that from being there before?

    With the "Injector Base Pulse Width Bank #" {GM.IBPW#} pid actually being the final or resultant pulsewidth, are there any other injector pid's that I should have been using to see that I was actually hitting those table limits? I think I have this particular car sorted out now, but just curious for future reference of identifying when the minimums have been hit to know when I absolutely need to deviate from correct supplied injector data.

    Thanks!

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