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Thread: Load and Torque

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    Load and Torque

    Hi Guys,

    Could someone please explain how the DME calculates load and infers torque?

    Thanks!

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    Hi Guys,

    Could someone please explain how the DME calculates load and infers torque?

    Thanks!
    Based on what @mfish reported, it appers there is a load to torque reference table but there is also calculated MAF and timing that influences load.
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Based on what @mfish reported, it appers there is a load to torque reference table but there is also calculated MAF and timing that influences load.
    How can load be a function of timing since timing is referenced on load? Is there a way to log load? It would really help to understand what the formula is for load or how it is generally inferred.

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    yeah load actual?
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    Click here to enlarge Originally Posted by enrita Click here to enlarge
    yeah load actual?
    Is this via Cobb? Do you know how it is calculated? Is it a table or function (would think it would have to be a function)?

    I guess I was thinking about it like this:
    The loading in 3rd is less than 4th which is less than 4th when you NLS. I got the tune solid for 3rd gear, and then had to turned down the timing on the last load line for 4th, but 4th after a NLS needs even less timing or more fuel. This load would be effectively off the map. I can compromise by pulling timing out of the last load line, but that will hurt performance on normal 4th gear pulls. Maybe there is an overload table we should be tuning, a change to the load calc, or an additional load line or two could be added to the map?

    Loads over 150 or so on the stock programming I believe were only in cases where you dropped the clutch or slammed a gear. Those were covered before, but with so much power now I think we are simply pushed off map and trying to make the final load line cover a variety of situations which are now “normal”.

    I guess I'm thinking that maybe rather than a torque limit kicking in, the timing actually does need to be pulled because the load would be so much higher after a quick gear shift. Conceivably if you are off map you are forced to convert your last load line into a compromise between worst case NLS shift or 4thor 5th gear pull. Of course, if load is not maxed post shift, then this cannot be the reason. If it can be logged during a flatland, I'd love to know what the value is.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge


    Is this via Cobb? Do you know how it is calculated? Is it a table or function (would think it would have to be a function)?

    I guess I was thinking about it like this:
    The loading in 3rd is less than 4th which is less than 4th when you NLS. I got the tune solid for 3rd gear, and then had to turned down the timing on the last load line for 4th, but 4th after a NLS needs even less timing or more fuel. This load would be effectively off the map. I can compromise by pulling timing out of the last load line, but that will hurt performance on normal 4th gear pulls. Maybe there is an overload table we should be tuning, a change to the load calc, or an additional load line or two could be added to the map?

    Loads over 150 or so on the stock programming I believe were only in cases where you dropped the clutch or slammed a gear. Those were covered before, but with so much power now I think we are simply pushed off map and trying to make the final load line cover a variety of situations which are now “normal”.

    I guess I'm thinking that maybe rather than a torque limit kicking in, the timing actually does need to be pulled because the load would be so much higher after a quick gear shift. Conceivably if you are off map you are forced to convert your last load line into a compromise between worst case NLS shift or 4thor 5th gear pull. Of course, if load is not maxed post shift, then this cannot be the reason. If it can be logged during a flatland, I'd love to know what the value is.
    I haven't looked at a stock timing and AFR table to see what load reference it goes up to, but i believe its at least 180, not 150. It sounds to me like you are just over-timed, banging through the gears is always a better indicator than attempting single gear pulls. Single gear pulls almost always look "peachy," especially when you can only see cylinder 1 Click here to enlarge

    My personal opinion is as long as not more than 3 cylinders correcting more than 3* is ok post shift.

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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    I haven't looked at a stock timing and AFR table to see what load reference it goes up to, but i believe its at least 180, not 150. It sounds to me like you are just over-timed, banging through the gears is always a better indicator than attempting single gear pulls. Single gear pulls almost always look "peachy," especially when you can only see cylinder 1 Click here to enlarge

    My personal opinion is as long as not more than 3 cylinders correcting more than 3* is ok post shift.
    It does go past 150 on the table. My theory was that you only hit that load on stock tuning if you bang a gear or go WOT in 6th or something. Now with the higher output we are seeing I think we are at max load much more often. Why this would mean then is that the car can't discern between load differences in 3rd, 4th, or 4th after you NLS. If you re at max load and it is applying the same timing/fuel to all those scenarios you will have to tune for the worst case scenario and lose power in other areas like 3rd gear. Either that or flatline.

    This is all speculating right now anyway though. If someone could log load on a 4th gear pull and then a 3 to 4 shift with flatline that would help a lot.
    Last edited by rudypoochris; 12-02-2013 at 12:14 PM.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    It does go past 150 on the table. My theory was that you only hit that load on stock tuning if you bang a gear or go WOT in 6th or something. Now with the higher output we are seeing I think we are at max load much more often. Why this would mean then is that the car can't discern between load differences in 3rd, 4th, or 4th after you NLS. If you re at max load and it is applying the same timing/fuel to all those scenarios you will have to tune for the worst case scenario and lose power in other areas like 3rd gear. Either that or flatline.

    This is all speculating right now anyway though. If someone could log load on a 4th gear pull and then a 3 to 4 shift with flatline that would help a lot.
    So the root issue you are having is flatline timing post shift on a 6MT(when using NLS)? You run a JB4, correct? I've never had timing flatline issues when using Cobb with a WOTBOX, but timing corrections post shift on 2-3 cylinders is rather normal. If you are over-timed it will greatly show during the shift. If you are in fact using the JB4 the DME only sees what the Jb4 is reporting, right? Making your entire assumption false.
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    So the root issue you are having is flatline timing post shift on a 6MT(when using NLS)? You run a JB4, correct? I've never had timing flatline issues when using Cobb with a WOTBOX, but timing corrections post shift on 2-3 cylinders is rather normal. If you are over-timed it will greatly show during the shift. If you are in fact using the JB4 the DME only sees what the Jb4 is reporting, right? Making your entire assumption false.
    msd80 makes a lot of things easier. Click here to enlarge

    Working on ije0s MT NLS flatline this week but it's definitely internal torque limit related just like the AT shift flatline.
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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    msd80 makes a lot of things easier. Click here to enlarge

    Working on ije0s MT NLS flatline this week but it's definitely internal torque limit related just like the AT shift flatline.
    Have you seen any success in changes to the load to torque limit table?
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Have you seen any success in changes to the load to torque limit table?
    The DME relationships between load and torque tables are complicated. Especially given the fact that some of the key tables are missing. But when you disassociate actual boost from DME load using a piggyback you have a lot more flexibility. We have found various combinations of DME load/torque that do not flatline at any RPM. The most widely used being our "AT" maps which are posted on n54tech for anyone interested in checking out the details.
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    So the root issue you are having is flatline timing post shift on a 6MT(when using NLS)? You run a JB4, correct? I've never had timing flatline issues when using Cobb with a WOTBOX, but timing corrections post shift on 2-3 cylinders is rather normal. If you are over-timed it will greatly show during the shift. If you are in fact using the JB4 the DME only sees what the Jb4 is reporting, right? Making your entire assumption false.
    No sure you are getting the heart of what I am getting at. People have flatlined on Cobb also, this isn't a JB4 issue.

    My theory - JB4 aside - was that post shift load could exceed the timing map's limits. If this happened the post shift timing would be assumed to match the last load line which also would correspond to the same load line on a normal 4th gear pull. Really has nothing to do with the JB4 other than the JB4 reading back what the DME is seeing.

    Brings me back to the original question - how is load calculated? If it can be logged, could someone please log a 4th gear pull and then a shift into 4th at WOT?
    Last edited by rudypoochris; 12-02-2013 at 03:43 PM.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    msd80 makes a lot of things easier. Click here to enlarge

    Working on ije0s MT NLS flatline this week but it's definitely internal torque limit related just like the AT shift flatline.
    What makes you think it is an internal limit rather than an off map scenario? When I logged 4th gear the car was basically at the last load line on the map. Knowing that shifting into 4th with NLS will be a large load spike past this, it would make sense to me that the load would shoot past the last line on the map. This of course would assume that load is not relational but rather absolute.

    If this theory is correct, more load lines would have to be added to the map or the load limits at those lines would have to be redefined. Potentially the load to torque table defines this limit and can be used to allow larger torque at a given load. If that were the case, then timing and fuel would need to be adjusted to match the new definition of that load line. In that way I could see the map widening to allow for programming in different timing for higher load values post shift.

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    Load very simply is boost with some dependence on rpm. Theres other factors but these are dynamic during a datalog.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Load very simply is boost with some dependence on rpm. Theres other factors but these are dynamic during a datalog.
    Can it be logged on a Cobb? It should be mass airflow, but that of course has completely changed from stock.

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    Not an "off the map" situation... piggies can have the same issue running lowish load targets.

    Likely your issue if MT is corrections based on knock sensor activity.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    Can it be logged on a Cobb? It should be mass airflow, but that of course has completely changed from stock.
    Yes, load and maf would be directly related. For many tuning purposes its difficult to use maf though so load is maf based on rpm.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    No sure you are getting the heart of what I am getting at. People have flatlined on Cobb also, this isn't a JB4 issue.

    My theory - JB4 aside - was that post shift load could exceed the timing map's limits. If this happened the post shift timing would be assumed to match the last load line which also would correspond to the same load line on a normal 4th gear pull. Really has nothing to do with the JB4 other than the JB4 reading back what the DME is seeing.

    Brings me back to the original question - how is load calculated? If it can be logged, could someone please log a 4th gear pull and then a shift into 4th at WOT?

    I'm not insinuating that its a Jb4 issue, just perplexed by your thought process of how this is an off map situation. FWIW, i've never seen a Cobb tuned 6MT car flat line timing post shift, but i'm sure anything is possible.
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Yes, load and maf would be directly related. For many tuning purposes its difficult to use maf though so load is maf based on rpm.
    But imagine the scenario of 4000rpm in 3rd and 4000rpm in 4th both at peak boost. This would be the same RPM and the same mass air. Are these then the same load? I would think so based on that definition, but I don't think it is the same load to the DME.

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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    I'm not insinuating that its a Jb4 issue, just perplexed by your thought process of how this is an off map situation. FWIW, i've never seen a Cobb tuned 6MT car flat line timing post shift, but i'm sure anything is possible.
    I guess the way I look at it is that load basically correlates to mass air flow. We are running much more air through the engine and thus load values would be much higher than stock, right? That could drive you off the end of the map if there was not enough load lines. In testing it would appear the timing in 3rd puts me around the 2nd to last load line and in 4th has me at the last load line. Thus when I slam the gear for 4th after NLSing, it isn't altogether surprising to think that load may be off map. Am I missing something?

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    Am I missing something?
    Wouldn't your Jb4 be reporting what it *thinks* the DME wants to see?
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Wouldn't your Jb4 be reporting what it *thinks* the DME wants to see?
    I’m jumping into this mid-discussion, but doesn’t that sort of end things? The JB will report to the DME whatever load values it is sending, which of course have no relation to actual load since the JB is decoupling boost from load.

    So OPs load table question would only be relevant/observable on a flash only setup that allows the DME to run whatever load tables the tune calls for.

    What am I missing here?
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    Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
    Wouldn't your Jb4 be reporting what it *thinks* the DME wants to see?
    Yes, I could see that effecting load. Its something to look into. If the JB4 scaled load down linearly it would be quite easy to add in additional load lines to the map that way.

    Regardless, this problem would exist on a flash only setup without the load being modified would it not? How do the flash tunes deal with load past the last load line? Say MAF increased 100%, how would you still fit on the same load axis?

    It would also really help to know how load is calculated. I don't think it can be purely RPM and MAF since that would indicate the same RPM in a different gear at the same boost is the same load.

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    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge
    Yes, I could see that effecting load. Its something to look into. If the JB4 scaled load down linearly it would be quite easy to add in additional load lines to the map that way.

    Regardless, this problem would exist on a flash only setup without the load being modified would it not? How do the flash tunes deal with load past the last load line? Say MAF increased 100%, how would you still fit on the same load axis?

    It would also really help to know how load is calculated. I don't think it can be purely RPM and MAF since that would indicate the same RPM in a different gear at the same boost is the same load.
    Would imagine Cobb had to write in their own code for load values not defined on the existing tables. Yea based on the above, I would think it would absolutely occur in a flash only setup, assuming the flatline is being caused by an undefined/too large load value. In fact, as noted above wouldn't stacking it eliminate the possibility for this? I guess we would need to know exactly what the JB tells the DME Re: Load to answer that.
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    Click here to enlarge Originally Posted by 135pats Click here to enlarge
    Would imagine Cobb had to write in their own code for load values not defined on the existing tables. Yea based on the above, I would think it would absolutely occur in a flash only setup, assuming the flatline is being caused by an undefined/too large load value. In fact, as noted above wouldn't stacking it eliminate the possibility for this? I guess we would need to know exactly what the JB tells the DME Re: Load to answer that.
    JB4 could eliminate this issue if the load scaling was linear or well defined. If the JB4 simply chops the ECU PSI when it gets over a certain max level, this would be an issue. @Terry@BMS mind sharing how the JB4 handles load that would otherwise be off the map? I believe it targets 190 as a max load? Does it simply crop the ECU PSI down to show no more than 190, or is it scaled across the board somehow?

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