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Thread: Need BLM advice

  1. #1
    Fuel Injected! brian617's Avatar
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    Need BLM advice

    Been tweaking, testing and tweaking my VE tables today and believe I'm really close except for one thing I cant seem to alter. After a drive and I sit in driveway with truck idling the BLMs drop all the way down to 106-108 or so in the 600-800rpm and 30-35Map cells. Everything else is getting real close, but these never seem to change. Is there another parameter I should be adjusting as well?

    I'll try to get a good data log tomorrow but for now here are some screen shots.
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    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  2. #2
    RIP EagleMark's Avatar
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    Look at your data and make sure it is showing Idle when at Idle, and Off Idle when Off Idle. Just wondering if you have an issue with the conversion since your doing well elsewhere?

    Have to seperate data as well I think you know? So your adjusting Off Idle fuel with Off Idle BLM data? For the Idle fuel table I usually make it identical to Off Idle, except for the 6-9 cells around where the engine idles.

    In the Off Idle table I like a smooth transition as shown in your 3D graph picture. For the Idle table it's OK to have say 6-9 cells that are flat with the same number to get idle dialed in.

    Remember the cell you are idling in is not the exact number the PCM is useing for fuel! It is interpolated from that cell and all surrounding cells.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    Super Moderator dave w's Avatar
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    The '427 PCM has two fuel tables and two spark tables (near idle / off idle). I would check the parameters ( %TPS usually 2.7 % & MPH usually 3 MPH) when the '427 is set to be in near idle. TunerPro RT is an excellent program, but the '427 near idle / off idle BLM averages are not 100% accurate. I use Microsoft Excel to accurately separate near idle / off idle data.

    dave w

  4. #4
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by EagleMark View Post
    Look at your data and make sure it is showing Idle when at Idle, and Off Idle when Off Idle. Just wondering if you have an issue with the conversion since your doing well elsewhere?
    When this happens the "Idle Spark" is enabled.

    Quote Originally Posted by EagleMark View Post
    Have to seperate data as well I think you know? So your adjusting Off Idle fuel with Off Idle BLM data? For the Idle fuel table I usually make it identical to Off Idle, except for the 6-9 cells around where the engine idles.
    I spent most of the afternoon adjusting the Off Idle VE first Using the Off Idle BLM data and got it real close. I moved to the Near Idle VE and actually copied the 1600,1200, 800 and 400 rows out of my Off Idle table. Then I adjusted the 1800,1400,1000 rows manually to fix the map. I then lowered the VE in the idle cells I was having trouble with and manually smoothed the table to what you see now. However it didnt have much if any affect.

    Quote Originally Posted by EagleMark View Post
    In the Off Idle table I like a smooth transition as shown in your 3D graph picture. For the Idle table it's OK to have say 6-9 cells that are flat with the same number to get idle dialed in.
    OK I was moving that direction but wasnt sure.

    Quote Originally Posted by EagleMark View Post
    Remember the cell you are idling in is not the exact number the PCM is useing for fuel! It is interpolated from that cell and all surrounding cells.
    I remember you mentioning that in another thread and have been applying that rule best I can.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  5. #5
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by dave w View Post
    The '427 PCM has two fuel tables and two spark tables (near idle / off idle). I would check the parameters ( %TPS usually 2.7 % & MPH usually 3 MPH) when the '427 is set to be in near idle. TunerPro RT is an excellent program, but the '427 near idle / off idle BLM averages are not 100% accurate. I use Microsoft Excel to accurately separate near idle / off idle data.

    dave w
    I hadn't given the Idle Spark table much thought at all, that could be what I'm missing as my Main Spark Table(open throttle) has been modified to a Vortec truck Map. Should the Open Throttle and Closed Throttle spark tables mimic each other like the fuel maps until you get into the idle cells as well?
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  6. #6
    Super Moderator dave w's Avatar
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    Quote Originally Posted by brian617 View Post
    I hadn't given the Idle Spark table much thought at all, that could be what I'm missing as my Main Spark Table(open throttle) has been modified to a Vortec truck Map. Should the Open Throttle and Closed Throttle spark tables mimic each other like the fuel maps until you get into the idle cells as well?
    I would try having both Open Throttle / Closed Throttle Timing tables nearly identical. Keep the near idle timing table near stock settings for engine start up ( 400 RPM's ~ 600 RPM's for Kpa's above 75). The start up timing is usually ZERO or negative a few degrees.

    dave w

  7. #7
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by dave w View Post
    I would try having both Open Throttle / Closed Throttle Timing tables nearly identical. Keep the near idle timing table near stock settings for engine start up ( 400 RPM's ~ 600 RPM's for Kpa's above 75). The start up timing is usually ZERO or negative a few degrees.

    dave w
    I will give that a shot. I also checked and verified that my Maximum TPS% and Maximum MPH Spark Idle parameters are at 2.3% and 4mph.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

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    RIP EagleMark's Avatar
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    Quote Originally Posted by brian617 View Post
    I hadn't given the Idle Spark table much thought at all, that could be what I'm missing as my Main Spark Table(open throttle) has been modified to a Vortec truck Map. Should the Open Throttle and Closed Throttle spark tables mimic each other like the fuel maps until you get into the idle cells as well?
    That's probably an issue!

    Your cam does not look to big but adding some spark to idle helps. So yes, mimic but more spark in idle table for idle and then feel it out but less idle spark in off idle spark table.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  9. #9
    Fuel Injected! brian617's Avatar
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    Ok, I copy and pasted Open Throttle spark table into Closed Throttle table and then raised spark in the cells I was having trouble with. Then I pulled more and more VE out until my BLMs got in the 124 range and figured that was close enough for now. Now I have developed an open loop idle surge and an off idle hesitation. Best I can figure the hesitation is that the auto .BIN needs more AE as I have a manual trans.

    How much AE should I add and where for starters?

    What can I do for the open loop lean surge?
    Attached Images Attached Images
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  10. #10
    Super Moderator dave w's Avatar
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    Quote Originally Posted by brian617 View Post
    How much AE should I add and where for starters?

    What can I do for the open loop lean surge?
    I would try adding 10% to both AE MAP and AE TPS, and see how that works.

    dave w

    A Wide Band O2 is an excellent tool for figuring out AE and open loop lean surge.
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  11. #11
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by dave w View Post
    I would try adding 10% to both AE MAP and AE TPS, and see how that works.

    dave w

    A Wide Band O2 is an excellent tool for figuring out AE and open loop lean surge.
    I have a Wide Band in the truck, just not sure what parameter to correct for open loop.

    I'll bump up the AE 10% and see what gives. I tried messing with it the other day and got carried away then had to revert it back to stock settings.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

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    RIP EagleMark's Avatar
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    Quote Originally Posted by brian617 View Post
    What can I do for the open loop lean surge?
    What does your "Open Loop AFR vs. Temperature vs. Vacuum" table look like? Depending on how that is set up... you may have pushed the six flat cells for idle to far?

    For the AE do as Dave said. The reason you found this issue now is your not running pig rich and it needs AE to compensate, before it was so rich it had AE already pre-installed!

    Another way to get an idea of how much AE your going to need to compensate for an Auto bin in a Manual trans is open a $0E manual bin. I don't have these $0D memorized like $42 but mans there's a lot more AE in a manual bin.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  13. #13
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by EagleMark View Post
    What does your "Open Loop AFR vs. Temperature vs. Vacuum" table look like? Depending on how that is set up... you may have pushed the six flat cells for idle to far?
    Quote Originally Posted by EagleMark View Post
    For the AE do as Dave said. The reason you found this issue now is your not running pig rich and it needs AE to compensate, before it was so rich it had AE already pre-installed!
    That's what I was thinking too.

    Quote Originally Posted by EagleMark View Post
    Another way to get an idea of how much AE your going to need to compensate for an Auto bin in a Manual trans is open a $0E manual bin. I don't have these $0D memorized like $42 but mans there's a lot more AE in a manual bin.
    I'll dig through the .BINs and see what I can find. I assume that there is a different AE curve for a manual, not just a percentage increase. Can you think of an $0E manual off hand?

    Thanks for the help Dave and Mark. Much appreciated!
    Attached Images Attached Images
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

  14. #14
    RIP EagleMark's Avatar
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    Man it's hard to find manual bins for the E trans PCMs?

    Change your "Open Loop AFR vs. Temperature vs. Vacuum" to 14.0 as the highest and that should cure your lean surge in OL. Everything else lower then 14.0 is a good thing for when cold.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  15. #15
    Fuel Injected! brian617's Avatar
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    Dave, the 10% AE in MAP and TPS sure did the trick for the throttle off idle hesitation. Now the only issue I'm having is a closed throttle in gear at speed to open throttle jerk. Would that be more AE MAP or more AE TPS related? I'm guessing MAP?

    Mark, I still have the lean surge in open loop after start up even after adjusting the table to 14.0:1 in any cell 14 or higher with no success. Then I remapped the table even richer and only gained a rich condition on a dead cold engine. Which then after some warm up, still open loop, turn back into a lean surge. When I does enter closed loop the idle settles but BLM is 140 or higher around 150 degrees F coolant temp. The BLM will return to 128 or close after engine is fully warm at 190-200 degrees but it takes driving the truck to get that tempature.

    I'm thinking I should revert the Open Loop AFR table to stock, then possible fool with my timing table some more. Maybe I just have too much advance and thats causing the surge? Or maybe there is a coolant temp bias I need to look at?
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

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