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Thread: 2021 Mustang GT - Stock transport delay parameter safe with long tubes?

  1. #1
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    2021 Mustang GT - Stock transport delay parameter safe with long tubes?

    Does anyone know if the factory ECU able to adjust and relearn for the slightly different position of the wideband sensor location on the various brands of long-tubes available for the platform? I see that some people raise the value but not sure if this is absolutely needed. What would happen if you didn?t adjust for it?

  2. #2
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    There literally a max delay learn value that answers this question. Max learn is 1 second stock, maximum capable if you raise it is 2 seconds

  3. #3
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    Quote Originally Posted by Jn2 View Post
    There literally a max delay learn value that answers this question. Max learn is 1 second stock, maximum capable if you raise it is 2 seconds
    Are you saying it makes more sense to adjust the max learn value rather than try to calibrate the transport delay? Just bump that up a bit and you're good to go?

  4. #4
    Potential Tuner MAV's Avatar
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    Interested in this as well. My current logged Transport Delay Total is 2-3 times the values in the table. I'm happy to let the computer learn its own delay table if that's what it does, but I'll definitely need to bump the Max Learn up a bit...


    Tune.jpg Scan.jpg

    How are the values in the Time Constant table used with the Transport Delay values to derive to total TD? Is it additive? Multiplied?

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    Potential Tuner MAV's Avatar
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    As a follow up, I increased the stock TD table values by approximately 40% across the board and ran some additional logs. The Transport Delay Total log values increased 15-30% across all cells logged. STFT and LTFT were less stable.

    I read on a previous thread of someone decreasing the stock TD table values, so I decreased each value by 10% and ran more logs. The Transport Delay Total log values ranged from a decrease of the initially logged values (with the stock TD table values) of about 10% up to an increase of about 3%, but in all cases are still much higher than the actual TD table entires (still by about 40%). Fuel Trims were even less stable than with the increased TD table entries.

    As of now, my only thought is that sticking with the stock TD table values leads to the most stable fuel trims among the three tests. The only other test I might try is to increase the stock TD table by a smaller percentage (say, 10% instead of 40%) and log to see what changes and how.

  6. #6
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    Quote Originally Posted by MAV View Post
    As a follow up, I increased the stock TD table values by approximately 40% across the board and ran some additional logs. The Transport Delay Total log values increased 15-30% across all cells logged. STFT and LTFT were less stable.

    I read on a previous thread of someone decreasing the stock TD table values, so I decreased each value by 10% and ran more logs. The Transport Delay Total log values ranged from a decrease of the initially logged values (with the stock TD table values) of about 10% up to an increase of about 3%, but in all cases are still much higher than the actual TD table entires (still by about 40%). Fuel Trims were even less stable than with the increased TD table entries.

    As of now, my only thought is that sticking with the stock TD table values leads to the most stable fuel trims among the three tests. The only other test I might try is to increase the stock TD table by a smaller percentage (say, 10% instead of 40%) and log to see what changes and how.
    So during the Training classes we were always suggested to increase the O2 Transport delay and Time Constant by 1.50 or 50%. this was to accommodate for the relocation of O2 sensor and also the heat coming off the exhaust valve. Ford uses "O2 transport delays" to determine when to read the O2 sensor. This delay is basically the amount of time from the exhaust gas leaving the cylinder to the point it will pass the O2 sensor. Sense the PCM is adaptive, it will try to learn exactly what the real transport delay is. this why we suggest being increased by 50%. Since Long tubes shed more heat than shorties and stock manifolds. The O2 sensor duty cycle needs to be turned up a little to let them get hot enough to do their job. I generally like to add about 50 degrees to the values where the PCM will start to try read the sensors. Not that it really is 50 degrees hotter ( Hego Tip temp Change), also o2 multiplier i set anything below 1.00 to 1 (o2 Duty Cycle Multiplier) since the LTs tend to be colder than stock, you want the computer to wait until it thinks the stock manifolds are hotter than they are, so they LT's are closer to the right real target temp. These values will let it learn quickly, and keep your truck emissions ready. Generally I will turn off the rear O2 sensors, except when I'm there to data log them. Reason being is they might not get enough heat to do their job correctly, and might throw false catalyst efficiency error codes. Usually leave them off unless the car has to meet Emissions. I am sure some of the other tuners will Chime in and help out also.

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    Especially with long tube headers you're going to want to get your O2 Transport Delay dialed in before moving on to MAF or SD tuning. There is an ECU learned offset but the closer you get to the actual values the better, especially in out-of-idle conditions (1500-5000 RPM). Getting these values dialed in effectively increases the responsiveness of your O2 fueling correction. By adjusting the transport delay from when fuel is injected to when the O2 sensors apply a correction, you can more accurately match the physical time the fuel takes to get to the sensors. End result, you'll see your short term corrections happen much quicker when there is a difference between the WB EQ and the Cmd EQ. However, applying a baseline correction across the entire table can result in slower short term corrections, poorer fuel economy, etc.

    General guidance would be to apply a baseline correction (+25%) across your idle columns (600, 1000, 1250 RPM) to account for the increased distance of the O2 Sensors, then data log O2 Transport delay using RPM & Airload as your column and row axis to determine the actual transport delay for the non-idle columns. You'll want to set your "Cell Hits Required" for the graph to 10 (or something similar) and increase the O2 Transport Delay Total channel polling interview to 20ms to ensure you're getting accurate data.

    Go out and work through populating as many cells as you can. Its often helpful to switch between drive modes, put the car in sport mode and manually switch between gears, etc. Once you've filled most of the cells in your data log graph, you can use some simple math to calculate the new values for the non-idle columns (1500-5000 RPM) in the Transport Delay table. Since the data in the Transport Time Constant table represents the physical sensor response time, you can subtract the Transport Time Constant value from the logged O2 Transport Delay Total value for each cell to determine the correct Transport Delay table values.

    Example for 1500 RPM @ 40% Airload:
    Logged O2 Transport Delay Total value: 0.494
    Transport Time Constant value: 0.260

    0.494 - 0.260 = 0.234 (New Transport Delay value)

    Here is a link to our instructions & calculator for making this process easy. Just click "Use Template" to create your own editable copy.
    Sector Racing - O2 Transport Delay Calculator

  8. #8
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    Thank you both for some insight into this. Makes a lot more sense now.

  9. #9
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    Quote Originally Posted by SectorRacing View Post
    Especially with long tube headers you're going to want to get your O2 Transport Delay dialed in before moving on to MAF or SD tuning. There is an ECU learned offset but the closer you get to the actual values the better, especially in out-of-idle conditions (1500-5000 RPM). Getting these values dialed in effectively increases the responsiveness of your O2 fueling correction. By adjusting the transport delay from when fuel is injected to when the O2 sensors apply a correction, you can more accurately match the physical time the fuel takes to get to the sensors. End result, you'll see your short term corrections happen much quicker when there is a difference between the WB EQ and the Cmd EQ. However, applying a baseline correction across the entire table can result in slower short term corrections, poorer fuel economy, etc.

    General guidance would be to apply a baseline correction (+25%) across your idle columns (600, 1000, 1250 RPM) to account for the increased distance of the O2 Sensors, then data log O2 Transport delay using RPM & Airload as your column and row axis to determine the actual transport delay for the non-idle columns. You'll want to set your "Cell Hits Required" for the graph to 10 (or something similar) and increase the O2 Transport Delay Total channel polling interview to 20ms to ensure you're getting accurate data.

    Go out and work through populating as many cells as you can. Its often helpful to switch between drive modes, put the car in sport mode and manually switch between gears, etc. Once you've filled most of the cells in your data log graph, you can use some simple math to calculate the new values for the non-idle columns (1500-5000 RPM) in the Transport Delay table. Since the data in the Transport Time Constant table represents the physical sensor response time, you can subtract the Transport Time Constant value from the logged O2 Transport Delay Total value for each cell to determine the correct Transport Delay table values.

    Example for 1500 RPM @ 40% Airload:
    Logged O2 Transport Delay Total value: 0.494
    Transport Time Constant value: 0.260

    0.494 - 0.260 = 0.234 (New Transport Delay value)

    Here is a link to our instructions & calculator for making this process easy. Just click "Use Template" to create your own editable copy.
    Sector Racing - O2 Transport Delay Calculator
    Niffty little tool you guys built, I have gone even less than 25% i have been pretty close with 10-15% factor. the good thing is you can dial this in later after you get the main portion of fuel trims dialed.

  10. #10
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    I have a great tune. For it

  11. #11
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    Quote Originally Posted by SectorRacing View Post
    Here is a link to our instructions & calculator for making this process easy. Just click "Use Template" to create your own editable copy.
    Sector Racing - O2 Transport Delay Calculator
    I want to sincerely thank you for sharing this tool. I've spent the weekend tweaking and logging the TD values, and after one more iteration, I should be dialed in and ready for the next step in tuning.

  12. #12
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    Thank you so much for sharing this!