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Thread: Tuning 1227747 VE tables in open loop with a wideband gauge

  1. #1
    Fuel Injected! mmigacz's Avatar
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    Tuning 1227747 VE tables in open loop with a wideband gauge

    Iíve seen a lot threads about tuning VE tables with BLM data. However, If I have access to a wideband to read AFR, what is the best procedure for tuning VE tables in open loop? This is what I plan on doing, let me know if this makes sense.

    -Warm the engine up to operating temperature
    -Set Closed Loop - CTS to Enable to the highest value to keep the ECM in open loop
    -Set all values in the Open Loop - AFR vs Temp table to 12.5
    -Set all values in the Choke - Cold AFR vs. VAC kPa table to 0
    -Set all values in PE Ė AFR table to 12.5
    -Vary the rpm and load and record AFR data from the wideband
    -Adjust VE tables until the wideband readings are 12.5 throughout the range of RPMís and loads.

    My assumption is the VE tables are dialed in now, right?]
    If Iím right I can bring all the values back to their original AFRís or tweak them if needed.

    Note: the only reason I picked 12.5 is itís a safe AFR. After the VE tables are dialed in I would move the AFRís closer to 14 when cruising or idling.
    Last edited by mmigacz; 11-20-2013 at 08:36 AM.

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    EFI GearHead ! EagleMark's Avatar
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    I had to edit your post do to Font color, there's a choice of forum colors here, dark and light. So I use light and could not see White fonts. You can use all font formatting if you want. But leave font color default and there will be no issues with people who use differant forum schemes.

    You've got the right idea. But choke really does not need to be messed with so it will still start and run. All data and adjustments are made warmed up anyway.

    Need to calibrate the WB as well for Stoich value of fuel since it is converted from Lambda. Actually the better/easier/accurate way is just use Lambda.
    http://www.gearhead-efi.com/Fuel-Inj...g-using-Lambda

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  3. #3
    Fuel Injected! mmigacz's Avatar
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    Quote Originally Posted by EagleMark View Post
    I had to edit your post do to Font color, there's a choice of forum colors here, dark and light. So I use light and could not see White fonts. You can use all font formatting if you want. But leave font color default and there will be no issues with people who use differant forum schemes.

    You've got the right idea. But choke really does not need to be messed with so it will still start and run. All data and adjustments are made warmed up anyway.

    Need to calibrate the WB as well for Stoich value of fuel since it is converted from Lambda. Actually the better/easier/accurate way is just use Lambda.
    http://www.gearhead-efi.com/Fuel-Inj...g-using-Lambda

    So the only AFR tables (fully warmed up engine) I should be looking at is in open loop is (Open Loop - AFR vs Temp) and (PE - AFR), right? The part that confused me is the notes from the (Open Loop - AFR vs Temp) table. It says:

    This table details corrections to the A/F ratio, based on engine temperature. It includes startup enrichment (choke).
    Also Choke - Cold AFR vs. VAC kPa effects commanded AFR while in Open Loop.
    The current commanded AFR is used in the BPW calculation. This is true of both open and closed loop operation. While in open loop the ECM generates the commanded AFR from two tables: AFR vs manifold vacuum and AFR vs coolant temperature. While in closed loop the ECM uses the stoich AFR term.

    Which table is AFR vs manifold vacuum? I was assuming it was the Cold AFR vs. VAC kPa table.

    Also, I should toggle my wideband to Lambda and target .85 (12.5/14.7), right?

    Note: I'm running 0% ethanol gas in this engine.
    Last edited by mmigacz; 11-20-2013 at 11:25 AM.

  4. #4
    EFI GearHead ! EagleMark's Avatar
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    I know that's what it says. But I've never tested to be sure? It does not add up if say warmed up and 13.0 AFR in "Open Loop - AFR vs Temp" then add like 3.00 for 40 VAC kpa for "Choke - Cold AFR vs. VAC kPa (Added to AFR vs. Temp)" then your cruising at 16.0 AFR? Poof, running OL is instant lean cruise? If it were subtracted you'd be PIG rich which is more on the safe side...

    Now at 0 Vac kpa od 0.00 would be WOT so staying at 13.0 is OK, but not optimal.

    That VAC kpa is kind of strange as it's 80 column is 100 MAP and 0 is 20 MAP. I've changed them on some other Parameters to be more user friendly to MAP, but truly not accurate as per dissasembly and the way the ECM calibrates it. Works good for end user.

    So while your doing this test it and let us know if it is truly used in OL warmed up as stated and added to Open Loop AFR, or just something with choke! We will add comments to XDF.

    Yup 85 Lambda for 12.5 AFR with Stoich of fuel at 14.7.

    The PIA of doing WB tuning in 7747 is no way to get WB data into same data log and TP history tables. So need to use the WB software and spreadsheets etc... this is why I usually just do the BLM data in $42 and save the WB for the WOT runs to do PE.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  5. #5
    Fuel Injected! mmigacz's Avatar
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    Quote Originally Posted by EagleMark View Post
    I know that's what it says. But I've never tested to be sure? It does not add up if say warmed up and 13.0 AFR in "Open Loop - AFR vs Temp" then add like 3.00 for 40 VAC kpa for "Choke - Cold AFR vs. VAC kPa (Added to AFR vs. Temp)" then your cruising at 16.0 AFR? Poof, running OL is instant lean cruise? If it were subtracted you'd be PIG rich which is more on the safe side...

    Now at 0 Vac kpa od 0.00 would be WOT so staying at 13.0 is OK, but not optimal.

    That VAC kpa is kind of strange as it's 80 column is 100 MAP and 0 is 20 MAP. I've changed them on some other Parameters to be more user friendly to MAP, but truly not accurate as per dissasembly and the way the ECM calibrates it. Works good for end user.

    So while your doing this test it and let us know if it is truly used in OL warmed up as stated and added to Open Loop AFR, or just something with choke! We will add comments to XDF.

    Yup 85 Lambda for 12.5 AFR with Stoich of fuel at 14.7.

    The PIA of doing WB tuning in 7747 is no way to get WB data into same data log and TP history tables. So need to use the WB software and spreadsheets etc... this is why I usually just do the BLM data in $42 and save the WB for the WOT runs to do PE.

    When I trial this, I will definitely post some feedback. Thanks.

  6. #6
    Fuel Injected! mmigacz's Avatar
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    I was tuning in open loop today. I set all the values in Open Loop - AFR vs Temp. to 12.5 AFR. Next, I set all the values in the Cold AFR vs. VAC kPa to zero. The engine was fully warmed up. I was watching the Wideband gauge and it was reading 12.5 after adjusting the VE tables (at about 1800 RPM, in nuetral). With my emulator I changed all the values in the Cold AFR vs. VAC kPa to 2 AFR. The wideband reading jumped from 12.5 to 14.5.
    1986 ski centurion boat, 351W, gt40P heads, edelbrock performer rpm, 1227747 ecm, 72 lb/hr injectors (@18 PSI fuel pressure), .490/.490 lift, intake 278 duration, exhuast 282 duration, 112 lobe separation

    1969 camaro, 355ci, performer RPM intake, camel hump heads, 1227747 ecm, 454 throttle body (@18 PSI fuel pressure),

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