Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 45

Thread: B4005 Small Pulse Adjust How does GM create this table?

  1. #21
    Lifetime Member SSpdDmon's Avatar
    Join Date
    Jun 2005
    Posts
    1,558

    Default

    That's my point. If it's a vacuum issue, why not just deal with it in the flow rate table.

    I too have a mad hatrid for the number 1.8 as I hit it all of the time during decel. On one hand, I want to learn why it's bottoming out there and figure out how to fix it the right way. On the other though, I just want the problem gone and am two steps away from the trial and error mentality.

  2. #22
    Lifetime Member
    Join Date
    Jul 2005
    Posts
    702

    Default

    Quote Originally Posted by onfire
    Another thing that really skews the SPA table is adding low imp injectors. Low imp injectors open and close much faster than stock high imp injectors and don't need as much offset to get the same area under the curve.

    What gives me heartburn is I've reduced the Minimum Pulse Width to 0.3 and the Default Pulse width to 0.3 and it does not lower the idle pw under the magic 1.8. The SPA and the Voltage Offset tables are adding to something else to create that minimum pw number.
    well yea, this pcm is not exactly designed to work with low impedance injectors, so the fact that it works at all amazes me

    you can tell the computer whatever you want about the minimum pulse width, but ultimately it's gonna to perform something it cannot physically execute. that's why it's important to find a way to convert the injector data into something that the PCM can understand. post all the data you got on your injectors, i'm working on a spreadsheet, might as well work on some real numbers.

  3. #23
    Lifetime Member SSpdDmon's Avatar
    Join Date
    Jun 2005
    Posts
    1,558

    Default

    Quote Originally Posted by redhardsupra
    well yea, this pcm is not exactly designed to work with low impedance injectors, so the fact that it works at all amazes me

    you can tell the computer whatever you want about the minimum pulse width, but ultimately it's gonna to perform something it cannot physically execute. that's why it's important to find a way to convert the injector data into something that the PCM can understand. post all the data you got on your injectors, i'm working on a spreadsheet, might as well work on some real numbers.
    Any ideas on SVO 30's while you're at it???

  4. #24
    Lifetime Member
    Join Date
    Jul 2005
    Posts
    702

    Default

    gimme data and i'll do it

  5. #25
    Lifetime Member jfpilla's Avatar
    Join Date
    Apr 2003
    Posts
    666

    Default

    Quote Originally Posted by onfire
    I've looked at a lot of GM files...B4005 has many differnt "looks" depending on what car /injectors it's in. It's not a standard slope.

    I've had to change mine bigtime to get 86lb low imp injectors to work in COS5. I've watched some of the changes by using RR in realtime....

    I'm getting close but would like to understand the small pulse adjustments better. The nice thing about the table is that it will command an adder where you want it....plus it can be a negative adder which is nice with big injectors.

    It and the voltage oddsets are the keys to big injector tuning.
    onfire,
    This is an interesting subject and I know nothing about it. It's hard to find answers. You might want to look at an LS7 file. The table values related to injectors are very different from LS1's. I have a crate LS7 in a C5. The injectors calculate to 41.8#s. I was having some surging problems and low rpms at hot startup. After putting in all the LS7 tables related to fueling ie: pw, default pw, fl.rate, min. pw etc. All the issues went away. I should log pw and see if it's as low as in the min. pw tables. It didn't occur to me until I read this.

    SSpdDmon,
    Am I not understanding? As manifold vacuum decreases pulse width increases and visversa in my tables.
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  6. #26
    Senior Member
    Join Date
    Mar 2006
    Posts
    180

    Default

    Quote Originally Posted by redhardsupra
    well yea, this pcm is not exactly designed to work with low impedance injectors, so the fact that it works at all amazes me

    you can tell the computer whatever you want about the minimum pulse width, but ultimately it's gonna to perform something it cannot physically execute. that's why it's important to find a way to convert the injector data into something that the PCM can understand. post all the data you got on your injectors, i'm working on a spreadsheet, might as well work on some real numbers.

    Here's where I'm going to start a firestorm...lol..

    With 86lb injectors or larger....the "IFR calculator" really jacks the VE table up wayyyy over 100% on cruise, etc....so that's an issue I'm still playing with by lowering the IFR slope by different percentages.....

    I'll get you some data tonight...would have it now but my RR skewed all my tuning data and I had to start over today without it.

  7. #27
    Senior Member
    Join Date
    Mar 2006
    Posts
    180

    Default

    I've looked for a LS7 file but did not find one at the Holden site. Do you know where one is? TIA.



    Quote Originally Posted by jfpilla
    onfire,
    This is an interesting subject and I know nothing about it. It's hard to find answers. You might want to look at an LS7 file. The table values related to injectors are very different from LS1's. I have a crate LS7 in a C5. The injectors calculate to 41.8#s. I was having some surging problems and low rpms at hot startup. After putting in all the LS7 tables related to fueling ie: pw, default pw, fl.rate, min. pw etc. All the issues went away. I should log pw and see if it's as low as in the min. pw tables. It didn't occur to me until I read this.

    SSpdDmon,
    Am I not understanding? As manifold vacuum decreases pulse width increases and visversa in my tables.

  8. #28
    Lifetime Member SSpdDmon's Avatar
    Join Date
    Jun 2005
    Posts
    1,558

    Default

    Quote Originally Posted by jfpilla
    onfire,
    This is an interesting subject and I know nothing about it. It's hard to find answers. You might want to look at an LS7 file. The table values related to injectors are very different from LS1's. I have a crate LS7 in a C5. The injectors calculate to 41.8#s. I was having some surging problems and low rpms at hot startup. After putting in all the LS7 tables related to fueling ie: pw, default pw, fl.rate, min. pw etc. All the issues went away. I should log pw and see if it's as low as in the min. pw tables. It didn't occur to me until I read this.

    SSpdDmon,
    Am I not understanding? As manifold vacuum decreases pulse width increases and visversa in my tables.
    Right...during decel....high man. vacuum...my pulse widths are too big. No matter what I do to the IFR, MAF, VE, or min. PW tables, it wants a 1.8ms pulse width and nothing smaller. I'm about to just lop it off of the voltage table where I see the problem (Man. vacuum >74kPa).

  9. #29
    Lifetime Member jfpilla's Avatar
    Join Date
    Apr 2003
    Posts
    666

    Default

    Quote Originally Posted by onfire
    I've looked for a LS7 file but did not find one at the Holden site. Do you know where one is? TIA.
    You will get one soon.

    I logged coming home and the pulse width at idle and decel are a little higher. So PW was not the issue. It could be the Commanded fuel when cranking values. They are much lower for the LS7.Or, maybe it's just a better balanced tune as I worked on it.
    It's raining so I could not do a WOT decel to observe min PW. I will, since I'm now curious.
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  10. #30
    Lifetime Member TAQuickness's Avatar
    Join Date
    Jan 2005
    Posts
    2,940

    Default

    Quote Originally Posted by SSpdDmon
    Right...during decel....high man. vacuum...my pulse widths are too big. No matter what I do to the IFR, MAF, VE, or min. PW tables, it wants a 1.8ms pulse width and nothing smaller. I'm about to just lop it off of the voltage table where I see the problem (Man. vacuum >74kPa).
    It's been a while since I tuned my SVO 42's, but I was getting stuck on the 1.8 ms PW as well. I was eventually able to get the commanded PW down to 1.5, but then I discovered that anything less than a 1.78ms PW and the injector wouldn't fire (AFR's in the 20's).

    I ended up tweaking the tune so I would see no less than a 1.79ms PW and made my DFCO a bit more agressive.


Page 3 of 5 FirstFirst 12345 LastLast

Similar Threads

  1. IBPW {B4005} {B3701} correlation
    By 5.7ute in forum General (Petrol, Gas, Ethanol)
    Replies: 22
    Last Post: August 12th, 2010, 09:19 AM
  2. small pulse adjust - 60Lb deka
    By fezz57 in forum Gen III V8 Specific
    Replies: 18
    Last Post: May 13th, 2010, 08:06 PM
  3. LMM Pulse table
    By killerbee in forum Duramax 06 LLY / 06+ LBZ & LMM
    Replies: 26
    Last Post: October 30th, 2009, 08:33 AM
  4. small pulse adjust {B4005}
    By acric5 in forum Gen III V8 Specific
    Replies: 8
    Last Post: October 22nd, 2009, 12:48 PM
  5. Small Pulse Adjust/Low Pulse Width Injector Offset
    By N0DIH in forum General (Petrol, Gas, Ethanol)
    Replies: 0
    Last Post: September 4th, 2007, 08:05 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •