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Thread: Whats the torque/ inverse calculation?

  1. #41
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by C_Murph12 View Post
    Are you guys using murfie's method turning off all MP except the one you are concentrating on? How safe is this? Multiple cam angles and spark tables run and various engine speeds... curious if that is actually safe, especially on a PD blower car.

    MPs establish a matching set of cam angles, spark tables, and torque tables. Disabling ones you are not using should be safe. There is nothing related to RPM or load that makes a certain cam angle unsafe, just not optimal for power or efficiency. Aftermarket cams are a different story. But you should use limiters that allow safe operation of bigger cams.

  2. #42
    Quote Originally Posted by CCS86 View Post
    MPs establish a matching set of cam angles, spark tables, and torque tables. Disabling ones you are not using should be safe. There is nothing related to RPM or load that makes a certain cam angle unsafe, just not optimal for power or efficiency. Aftermarket cams are a different story. But you should use limiters that allow safe operation of bigger cams.
    Makes sense now that I think about it.

    Quote Originally Posted by murfie View Post
    The way I suggest to do it is start by modifying the load values. I first find my desired/ETC/driver demand torque in the torque tables. The PIDs read nearly the same when things are not way off.
    To find our values to replace that 1 and get our desired torque values we can multiply the load and torque of the Y axis of the torque and inverse tables. X*Y=1 As long as your maximum driver demand falls somewhere near the bottom of the tables everything should work out. And because ETC goes below 0 we end up with a load floor for that 0 torque row. All you have to do is setup a Graph with these values in the rows and using PID ETC TQ. Then set the columns to the RPM range in your tables. I suggest making them slightly higher than your red line. Then have the table fill with your air load.
    In the Whipple calibration I see a few different channels marked as 'Load" which one is it that I should be using for this?
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  3. #43
    Senior Tuner CCS86's Avatar
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    Usually absolute or air load is the value you want.

  4. #44
    Thanks CCS86. I'll mess with this tonight.
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  5. #45
    Senior Tuner CCS86's Avatar
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    Here's a puzzle for you guys. What is going on here?

    Pedal position, abs load, and RPM are all pretty stable, yet TQ error and ETC angle spike repeatedly. No limits are active during this, and it is 100% OP MP.



    TQ-ERR-Spikes.png
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    Last edited by CCS86; 08-16-2018 at 11:33 AM.

  6. #46
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    Quote Originally Posted by murfie View Post
    Axis values in graph for torque should be from the values in your tune. I hope you are not trying to put those in your tune. Its like that in the spreadsheet just for inverse purposes.
    ETC torque request doesnt put you quite in the right place in the table. in certain areas when you are at MBT spark, stoich fuel, and STP ambient conditions it may be close, but other times it could be way off. Using the desired indicated torque will. Calculated load is the % of indicated torque maximum. I think there is a desired indicated PID you might be able to use and not have to make a math. Keep in mind these inverse tables are trying to describe the relationship between calculated load(pedal control) and absolute load(engine control), both use them as a reference, just at different values.
    Those values are correct for a Whipple calibration. One problem I see with this is the lack of a standard for which channel (you guys call them PIDs) we are discussing. On one hand you are telling people to use ETC torque request and then your suggesting desired indicated torque, can you clarify?

  7. #47
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by CCS86 View Post
    Here's a puzzle for you guys. What is going on here?

    Pedal position, abs load, and RPM are all pretty stable, yet TQ error and ETC angle spike repeatedly. No limits are active during this, and it is 100% OP MP.



    TQ-ERR-Spikes.png



    No ideas?

    This behavior seems to repeat regularly 100 - 110% absolute load, in MPOP and nowhere else.

  8. #48
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by CCS86 View Post
    No ideas?

    This behavior seems to repeat regularly 100 - 110% absolute load, in MPOP and nowhere else.
    What is your inferred MAP doing at that point?

  9. #49
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by veeefour View Post
    What is your inferred MAP doing at that point?

    It's very stable, looking like the absolute load trend. Download that log file if you want to check it out.

  10. #50
    When making corrections to the torque tables using the calculator am I adding or subtracting based on my histograms. I set up two custom graphs. They both log load/RPM, the first subtracts EI Torque Reference from Driver Demand, the second subtracts Driver Demand from EI Torque Reference. Obviously one is a positive number and one is negative. Just not sure which I apply
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  11. #51
    Advanced Tuner small tuner's Avatar
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    Any one got lucky and have MP plot work in histogram and can share as murph described his theory on calculating TQ and TQ invers

  12. #52
    I can post my histogram if that's what you're referring to..
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  13. #53
    Advanced Tuner small tuner's Avatar
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    Quote Originally Posted by C_Murph12 View Post
    I can post my histogram if that's what you're referring to..
    Yes sir

  14. #54
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by CCS86 View Post
    It's very stable, looking like the absolute load trend. Download that log file if you want to check it out.
    So your SD model has to be changed.

  15. #55
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by veeefour View Post
    So your SD model has to be changed.

    What makes you say that?

    SD tables seem to primarily control the calculated MAP. In this case, even though the throttle blade is dancing around, you can see that the MAF rate is relatively stable, this means the absolute load is relatively stable. Absolute load drives the SD calculations, so the calculated MAP is pretty stable. Why would any of that need to change?

    The issue I'm having is that IPC Wheel Torque errors are causing the throttle to oscillate. I don't see how SD could cause this.

  16. #56
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    Quote Originally Posted by CCS86 View Post

    The issue I'm having is that IPC Wheel Torque errors are causing the throttle to oscillate. I don't see how SD could cause this.
    Adjust your torque tables, (& of course inverse) See if that helps your IPC errors any.

  17. #57
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by MRRPMBRP View Post
    Adjust your torque tables, (& of course inverse) See if that helps your IPC errors any.


    I have tried that without any luck. Honestly, the magnitude of these torque errors doesn't even make sense in the context of torque tables being the cause. At one point I had a spike of torque error that was over 300 lb ft. It's just not possible for your torque table to be off that far.

    Plus, look at the log I posted above. Torque tables are driven by absolute load and rpm, both of which are stable in that time period when torque errors are spiking and going back to 0.

  18. #58
    Supercharger bypass?

  19. #59
    Senior Tuner CCS86's Avatar
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    Quote Originally Posted by dsblk93gt View Post
    Supercharger bypass?


    How could the physical bypass valve cause IPC Wheel Torque Errors?

  20. #60
    Senior Tuner CCS86's Avatar
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    I have continued to try testing modifications to the throttle body tables and the torque tables, still unable to make sens of them.

    Here are 3 log sections form the same drive. Smooth roll ons, with very different behavior. All of them trace the same path down the 3000 rpm column, ending at 1.2 load. Two of them have IPD TQ Errors, and one doesn't have any.


    Tq-err.png
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