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Thread: Fuel Learn Table

  1. #11
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    Quote Originally Posted by Rick90lx View Post
    Danny, once the system has Learned and you start lowering the amount if Closed Loop Compensation %, should you also lower the Learned Compensation Limits %?
    Yes. After Learning has finished self-tuning all areas of the Fuel Table, the Closed Loop and Learned Compensation Limits should be decreased.

    • Idling: Once the Learning has finished self-tuning the Base Fuel Table, enter the Learn Parameters and decrease the Learned Compensation Limits % down to around 2% in the idle area. The reason why is, the idle can go through repeated 'cycles of Closed Loop compensation' (+/−). When you're idling for a long period of time, the electric fans are regulating the cooling system temperature between 200° & 190°. This temperature variance can cause the Closed Loop to add & subtract a significant amount of fuel (as it should), especially if the fans are powerful & blowing hot air at the throttle body. However, you don't want the Learn Table to constantly modify the Base Fuel Table with these temporary corrections. If you shut off the engine during the lean end of the "cycle", the Learn Table has self-tuned the idle area as such, and may run momentarily lean on the next startup. Closed Loop is not saved, so it's allowed to constantly fine-tune the AFR. Learning is saved (and its values modify the Base Fuel Table), so it should be limited once the engine is tuned.

    • Learning: Once the Learning has finished self-tuning the Base Fuel Table, enter the Learn Parameters and decrease the Learned Compensation Limits % down to around 10% (or less) in the entire table (except idle - 2%). The reason why is, if the WBO2 sensor fails, you don't want a significant amount of WBO2 correction happening, because it will then corrupt the Learn Table with false values. After the defective WBO2 sensor is replaced, the Learn Table would have to be cleared and the Learning starts all over again (if the Learning wasn't Transferred to Base recently). This can be avoided by decreasing Compensation Limits down to around 10% (or less). Remember, the Closed Loop isn't saved, so there's no corruption there. But the Learn Table is saved (and its values modify the Base Fuel Table), so limit its compensation once the engine is tuned. Of course, the Closed Loop Compensation Limits % can also be decreased once the Learning has self-tuned the engine.

    I ask because my Closed Loop Compensation Limits were at 100% in boost, and the Learned Compensation Limits were defaulted at 150%. That never made much sense to me.
    • At first, the ECU needs those Compensation Limits set high, so it can make significant tuning
    adjustments. Some base calibrations are farther from ideal than others, but the Closed Loop/Learn
    will tune it right. Initially, the ECU just needs to be allowed to do the most it can.

    • The Target A/F Ratio Table is the "commander". Everything (WBO2 sensor, Closed Loop operation, Learn
    Table, Base Fuel Table, etc.) works off of it to maintain the programmed AFR, so it must be right. After
    the EFI system is initially tuned, changes can still be made to the Target A/F Ratio Table, and (before
    exiting the TAFR screen) you have the option of automatically adjusting the Fuel Map. It's a great feature.

    • Closed Loop functions off of the WBO2 sensor.
    Learning functions off of the Closed Loop operation.
    Which is why Closed Loop must be active for Learning to occur.

    • The Base Fuel Table doesn't change its displayed values unless you Transfer Learning To Base.
    However, it is always in a modified state because the Learn Table values are applied to it.
    Closed Loop and Learning happens in "real time", but only the Learning is saved (Learn Table).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  2. #12
    Join Date
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    Thanks again for taking the time, that makes a lot of sense. I was reluctant to start reducing it, but I learned a few things about how much fuel I should be commanding. The Learn Table now shows -1% or -2%, instead of adding anywhere which makes me feel a lot safer.
    93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

  3. #13

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    Relative to Learn Table; which cell shows more learning (2.2) or (-1.6). Also, would the entire table need to read similar cell readings to be considered Learned, and therefore able to have the Learned Compensation Limits % reduced? Thanks, Jim

  4. #14
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    Quote Originally Posted by FordTBI View Post
    Relative to Learn Table; which cell shows more learning (2.2) or (-1.6).
    It depends on the Base Fuel Table value in that cell. The Learn Table can still indicate a negative number while adding fuel.
    Example: A Learn Table value of −20, changing toward −10, is adding fuel (even though both numbers are negative values).
    Example: A Learn Table value of 20, changing toward 10, is subtracting fuel (even though both numbers are positive values).

    Also, would the entire table need to read similar cell readings to be considered Learned...
    The purpose of the Learn Table is not to achieve similar values, high/low values (0% or 100%), or any value in particular.
    It's simply indicating the amount of tuning applied to the Base Fuel Table. Read this thread, that's what it's all about.

    ...and therefore able to have the Learned Compensation Limits % reduced?
    When the Learn Table values stop making significant changes, the ECU is finished self-tuning.
    You can then Transfer Learning To Base (which clears the Learn Table), and blend the Fuel Graph smooth.
    When the engine is tuned & running well, you should decrease the Closed Loop and Learned Compensation Limits % to lock in a good tune.
    I decreased my Learned Compensation Limits to 2% in the idle area (10% elsewhere). My Closed Loop Compensation Limits are 50% or less.

    EFI Software Help Information/Instructions:
    ‒ On the top Toolbar, click "Help" & "Contents". This opens all Help topics.
    ‒ When navigating the software, click "Help ?", drag it to any parameter and click again.
    ..This automatically opens the definitions for that specific parameter.
    ‒ Tuning information can be read by clicking the F1 key, when you're viewing any screen.
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual & Diagrams)
    http://documents.holley.com/techlibrary_199r10544.pdf (Holley EFI Help/Instructions Overview)
    http://documents.holley.com/techlibr...r10546rev1.pdf (Holley EFI Quick Start Guide)
    http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)
    Open the Holley EFI software "Help" Contents ("Help" drop down menu), and read "Step-By-Step Beginners Tuning".
    Ensure the EFI software is set to run as an "Administrator" (right click for Properties/Advanced). Set it and forget it.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #15

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    Danny, relative to the Learn Table, which cell shows more Learning (2.2) or (-1.6). But apparently I'm not communicating effectively. I've read all of the documents available from Holley and referenced, by you & others on this forum, but have been unable to find an answer, that I can reconcile to this question. I fully understand that the Learn Table modifies the Base Fuel Table. "The values reveal “self-tuning” that occurred on specific cells. The numbers reflect an offset percentage that is applied to the Base Fuel Table in order to comply with the Target A/F Ratio (Fuel ICF Definitions - Learn Table Help section). This would indicate to me that the smaller the numerical value (either + or -) the less modification and therefore the more Learned. Correct? Yes or no?

    If the answer is yes, then, it appears to me, the goal would be to have the entire Learn Table populated with similarly low numeric values to show a completed self-tuned Fuel Table. Yes or no?

    From my readings, I suspect this is not possible. I suspect that is why you qualified your answer, "When the Learn Table values stop making significant changes, the ECU is finished self-tuning." However, I've been unable to locate a document that will, define "significant changes". Are we talking a decimal point, 1 or 2 whole numbers, what?

    I appreciate your comment as to your Closed Loop & Learned Compensation Limits. It gives a guideline (something I've not been able to find in any of Holley's documents) for a novice to follow.

    A follow-up question I have. Have you found that a locked-in tune prevents intermittent and spurious driveability issues? Thanks for your time & help.

  6. #16
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    The values in the Learn Table will only be close to zero if there is no need for a change to the Base Fuel Table.
    Example: (I'll use just one cell.)

    You have a base value of 100 lb/hr.
    It's too rich, so the ECU removes fuel, Learn Table shows -20%.
    If the base is left at 100, it will always show -20% in the Learn.
    Once you "Transfer Learning To Base" the base value will change to 80 lb/hr (100-20%).
    The Learn Table will be reset to zero.
    If it needs more fuel correction, the Learn Table will show that.

    AFTER you have Transferred Learning To Base, if the values show more than +/- 5%, it needs more correction in that area.

    If you choose not to Transfer Learning To Base, it will continue to show that 20% value forever or until you transfer it.
    At that point, if it shows 20%, and hasn't moved more than 5% either way in a while, Learning can be considered complete.

    You technically NEVER have to Transfer Learning To Base, but it's good practice to do it at least once after the Learn Table has been
    well populated with values, so you have a clean zeroed out table to watch for other issues or places where more Learning needs to occur.

    Once you have the tune dialed in well, +/- 5% either way is common to see day to day due to weather changes & elevation changes.
    Don't worry if your tune is not "Perfect", it will be constantly changing by small amount and you will never be able to get it 100% perfect.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  7. #17

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    I currently run with Closed Loop "Enabled" and Base Fuel Learn (BF Learn) "Disabled".

    Q1: Base Fuel Learn “Disabled” only prevents the Learn Table from being updated, and does not prevent the CL Comp Table from making changes to the Fuel, correct?

    Q2: Let’s say I leave the Base Fuel Learn “Enabled” and make the Learned Compensation Limits % numbers small, say +/- 2%, and set the Close Loop Compensation Limits % numbers high, say +/- 100%. If WBO2 detects a Lean situation that requires a 15% increase in fuel, I believe the Learn Table will max out at +2%, but the Closed Loop Compensation correction will increase the actual fuel by the needed 15% (regardless of what the Learn Table says). Is this correct?

    Q3: Example: CL Compensation Table has +/-100%. Base Fuel is 400 lb/hr. If my WBO2 dies and shows either a very lean or very rich reading, the +/-100% CL Comp Table setting would let the fuel go from anywhere between 0 lbs/hr up to 800 lbs/hr, depending on how that sensor dies (low or high state). Is this correct?

    Q4: If Q3 is correct, I see where Danny mentions "My Closed Loop Compensation Limits are 50% or less." This 50% seems to be a very high and dangerous setting if there is any type of unforeseen failure, isn’t it?

    Q5: I'm a bit confused what triggers Closed Loop Comp (in Datalogs when CLStatus flips from OpenLP to/from ClosedLP). I have the following setup:
    - Enable Closed Loop.
    - Enable RPM to Enter CL: 1500 RPM.
    - Advanced Control: 3 (Would love to know what each of these settings actually do.)

    Q5A: I see the following in my datalogs. When I'm on the 2-Step at say 5500 RPM, I see the CLStatus change from OpenLP to ClosedLP (not very often, but it happens), without any change in RPM. So not sure what triggers it? What other parameter besides RPM is being used as a trigger? I'm attaching a JPG of this.

    Q5B: I assume when on the Boost Builder it defaults to OpenLP mode. Once I leave the line, I see the CLStatus change from OpenLP to ClosedLP about 0.20 Sec into the run, this happens all the time at 0.20 sec. Why does it not change at the instant the car leaves the starting line. Does this have anything to do with the "Advanced Control" of 3 adding some delay for the change of state? Thanks, Steve

    Click image for larger version. 

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    Last edited by ijs12fly; 06-15-2016 at 03:42 PM.

  8. #18
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    Quote Originally Posted by ijs12fly View Post
    Q1: Base Fuel Learn “Disabled” only prevents the Learn Table from being updated, and does not prevent the CL Comp Table from making changes to the Fuel, correct?
    Correct, Closed Loop still functions with Learn disabled. Of course, if Closed Loop is disabled, Learning is too.

    Q2: Let’s say I leave the Base Fuel Learn “Enabled” and make the Learned Compensation Limits % numbers small, say +/- 2%, and set the Close Loop Compensation Limits % numbers high, say +/- 100%. If WBO2 detects a Lean situation that requires a 15% increase in fuel, I believe the Learn Table will max out at +2%, but the Closed Loop Compensation correction will increase the actual fuel by the needed 15% (regardless of what the Learn Table says). Is this correct?
    Yes, because you've only limited the Learned Compensation Limits %, not the Closed Loop Compensation Limits %.

    Q3: Example: CL Compensation Table has +/-100%. Base Fuel is 400 lb/hr. If my WBO2 dies and shows either a very lean or very rich reading, the +/-100% CL Comp Table setting would let the fuel go from anywhere between 0 lbs/hr up to 800 lbs/hr, depending on how that sensor dies (low or high state). Is this correct?
    Yes. That's why when the engine is well tuned, you should decrease the Closed Loop and Learned Compensation Limits % to lock in a good tune.
    I decreased my Learned Compensation Limits to 2% in the idle area (10% elsewhere). My Closed Loop Compensation Limits are 50% or less.
    When the Learn Table values stop making significant changes, the ECU is finished self-tuning.
    http://forums.holley.com/showthread....7370#post47370 (Learn Table - Read this thread, especially posts #2, #6 & #11.)

    And if the Learned Compensation Limits % are significantly decreased (as they should be after the engine is tuned),
    the Closed Loop Compensation can save the engine without skewing the Base Fuel Table.
    So you can fix a temporary fuel system fault without necessarily having to fix the "tune".
    http://www.yellowbullet.com/forum/sh....php?t=1000178 (Related Forum Thread)

    Q4: If Q3 is correct, I see where Danny mentions "My Closed Loop Compensation Limits are 50% or less." This 50% seems to be a very high and dangerous setting if there is any type of unforeseen failure, isn’t it?
    Yes, it can be. Program the Closed Loop Compensation Limits to what you feel is appropriate for your engine. However, I have dual NTK WBO2 sensors (very reliable & durable) with the Innovate Motorsports HBX-1 Heat Sink Bung Extenders. I believe the Innovate Motorsports HBX-1 Heat Sink Bung Extenders actually prevent a lot of WBO2 sensor failures. They work great with Bosch or NTK WBO2 sensors. I've never had a Holley EFI WBO2 sensor go bad, and I'll probably replace the WBO2 sensors before they do.

    Q5: I'm a bit confused what triggers Closed Loop Comp (in Datalogs when CLStatus flips from OpenLP to/from ClosedLP). I have the following setup:
    - Enable Closed Loop.
    - Enable RPM to Enter CL: 1500 RPM.
    Closed Loop & Learning isn't active during periods of acceleration enrichment or deceleration (zero TPS, 400 RPM above target idle).
    The engine needs to be at "steady-state" RPM for the Learning to function, at lower RPM.
    The Closed Loop Status has many momentary periods when it's inactive (Open Loop mode).
    This is normal due to the TPS & MAP based acceleration enrichment (transient fueling).
    Also, any "noise" on the TPS or MAP signal wire (false Rate of Change) will deactivate Closed Loop.
    https://www.holley.com/document/tech...__statuses.pdf (Sensor Diagnostics & Statuses)

    - Advanced Control: 3 (Would love to know what each of these settings actually do.)
    http://forums.holley.com/showthread....8268#post48268 (Closed Loop Parameters - "Advanced Control" 1, 2, 3, 4, 5)

    Q5A: I see the following in my datalogs. When I'm on the 2-Step at say 5500 RPM, I see the CLStatus change from OpenLP to ClosedLP (not very often, but it happens), without any change in RPM. So not sure what triggers it? What other parameter besides RPM is being used as a trigger? I'm attaching a JPG of this.
    Holley EFI goes into Open Loop during the 2-Step activation (a good thing), so the Fuel Table must be well tuned in that location.
    Look at the Learn Table. If it hasn't self-tuned that area (because you may not normally reach that area), then tune it manually.

    Q5B: I assume when on the Boost Builder it defaults to OpenLP mode. Once I leave the line, I see the CLStatus change from OpenLP to ClosedLP about 0.20 Sec into the run, this happens all the time at 0.20 sec. Why does it not change at the instant the car leaves the starting line. Does this have anything to do with the "Advanced Control" of 3 adding some delay for the change of state?
    0.20 seconds is quick. I'm not sure on this one. Change the Closed Loop Advanced Control value and see if it changes the delay.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  9. #19

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    Danny, thanks for the very thorough response.

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