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Thread: LNF Optimum Spark tables - how to

  1. #1

    LNF Optimum Spark tables - how to

    First, let me say that you should thoroughly read and reread ALL of CobaltSSOverboosters threads as well as GMTech's posts and others. Then reread again. These are advanced tables which should not be manipulated without full understanding of the LNF ecm.

    Second, I don't post a lot for a reason. But, I think with all the help of the previous pioneers it is important to continue to extend the knowledge gained to others. I WILL NOT SHARE NUMBERS WITH ANYONE. THIS IS A HOW-TO, NOT A HOW MUCH THREAD. YOU WILL HAVE TO LEARN ON YOUR OWN. NO FREE HANDOUTS.

    Third, ALL of my changes together will give your LNF a linear cable-driven throttle feel. They require a full retune from scratch when you make several of these changes. Why? Because many tables act as "urgency" tables. What does this mean? If I have $21 to my name and I loan you $20, when I need it back I need it back NOW because it's extremely important to me. If I have a million dollars and I load you $20, getting it back is irrelevant. This is how many of the tables function. Changing one will greatly affect others which need to be raised. The end result will be a smooth, fully functional ecm. But, it will be frustrating at times.

    READ GMTECH'S WRITEUP ON OPTIMUM SPARK TABLES FIRST. His description is spot on. It took me experimenting to understand what he had written. This is merely to explain HOW to manipulate the optimum spark table.

    Some important points

    - The optimum spark table is an urgency table for the ecm and is directly related to the main spark.
    - The values in the optimum spark table are completely irrelevant.
    - The optimum spark table is a DIFFERENCE table. The numbers that matter are the values in the optimum spark table MINUS the values in the main spark.
    - Changes to the optimum spark table can make it try to boost way to quickly out of control OR not boost at all up to redline.

    HOW TO ADJUST THE OPTIMUM SPARK TABLE

    Like I said above, it is a difference table. I will first list how to make changes to the optimum spark and the main spark. Then, I will explain what's happening.

    To adjust the optimum spark table:

    1. Like your main spark, all four OS tables should be the same. Very important.
    2. Highlight and copy an entire main spark table
    3. Highlight an entire OS table.
    4. Right click -> paste special -> SUBTRACT. You are subtracting the MS table from the OS table. The values you are left with (the difference) is what you will adjust.
    5. Adjust your OS table.
    6. Highlight that adjusted OS table.
    7. Right click -> paste special -> ADD. You are adding back in the values of the MS table that you subtracted.
    8. Don't forget to copy that new OS table to the other three old ones.

    Step #7 is very important. If you forget to add it back in, the car will run like it's in limp mode for a reason that will be explained below. Ask me how I know


    To adjust your main spark table without affecting your optimum spark values:

    1. Highlight and copy an entire main spark table.
    2. Highlight an entire optimum spark table.
    3. Right click -> paste special -> SUBTRACT. You are subtracting the old MS table from your OS table leaving you with your OS values that you DON'T want to change.
    4. Make the changes you want to your main spark table.
    5. Copy that main spark table to the other three old MS tables.
    6. Go back to the OS table that you subtracted from and right click -> paste special -> ADD. You are adding your new MS values to the old OS values you didn't want to change.
    7. Copy the "new" OS table (same OS values with the new MS changes added to it) to the other three "old" OS tables.

    This will let you make timing changes without changing the optimum spark. Remember, it's an urgency table. Just because you want different timing values doesn't mean you want to change the urgency with which they are applied.



    WHAT THE OPTIMUM SPARK TABLE IS DOING

    Like Mike said below (thanks), this is one of the more dominant urgency tables. When talking about what it does, I will be referring to the DIFFERENCE with the main spark table subtracted. Like the money example above, negative numbers mean little urgency while positive numbers mean you are more desperate for results.

    Start with the stock table. With the stock timing subtracted, notice how the numbers in the low load, high rpm area are negative? Also notice how in the high load region they approach 23+? What this does is tell the ecm that making torque (everything involved from timing to boost, etc) in low load high rpm areas is unimportant. Conversely, it's saying there is much more urgency in the higher rpm and load regions.

    When you have been changing timing without adjusting the optimum spark along with those spark changes as noted above, you were unknowingly also changing the urgency with which you were requesting power. That's why you can make several main spark changes and think "wow the engine really woke up!" or "man the engine went flat just with a timing change. What gives?" It wasn't always the timing as much as it was the difference between main spark and optimum spark.

    As a safe method of seeing what power the optimum spark table has, set the difference (as explained above) to "-10" across the whole table. I like using "-10" as a more dramatic example. Add your main spark table back in and go make a pull through the gears. Then, repeat with making the entire difference "5" or "10" like Mike said and make another run. This will give you an understanding of HOW to manipulate the optimum spark and what it does to overall performance with a single table. "50" seems to be the max for instability on a stock turbo. Stay well below this.



    One final note on linear pedal. Why set the entire difference to a single value? It makes the table's response linear. It sees a constant "urgency" request. I've tried ramping it and it makes the pedal exponential. Making the table a single value doesn't change the urgency of the pedal regardless at what percentage you are. The ecm responds by ramping torque in linearly. This combines with other tables mentioned to create a cable-driven pedal feel.
    Last edited by codename Bil Doe; 04-02-2014 at 11:44 AM.

  2. #2
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    As a trial, take the whole Optimum Spark table and make all of it -5. Then copy your Main Spark table and paste special add to the Optimum Spark table you just made -5. This will make all of the number in Optimum Spark 5 less then every value in your spark tables. Go log. After that use 10 instead of -5 and go log. This should give you a general idea of how this table works. Your Main Spark tables NEED to be on point first.

    I will reiterate that these are advanced tables and should not just be played with. Use at your own risk.

  3. #3
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    It also needs to be stated that EVERYONES results will vary based on their cam timing when working with the OS tables. What may work for Bill or Mike may not work for you.

    Bill has really helped to shed some light and I will say, I'm running the stock cam timing (Cobalt) and my OS timing is vastly different than his but yet I'm getting the results I'm after by simply following the 'urgency' tip that Bill provided.

    I will also mention that if you decide to get too greedy with regard to high load/high RPM 'urgency', you may experience the ECM closing the TB. You also need to be wary of just how aggressive you get with low load/low rpm OS 'urgency' as you can push it to the point where the car will literally accelerate by itself or run into a severe throttle hanging situation.


    Thanks again Bill
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  4. #4
    Thanks, T-Man. Extremely important to note that this is a HOW-TO guide. Even if I gave you my exact numbers (Solstice GXP -which I won't and no one else should, either), it will be very different for you based on your car and setup.

    T-Man - I tried to give a hint about greediness. Ask me how I know about over/underboost limp mode on track. Gotta learn somehow!

  5. #5
    Here is an example of how to prepare the optimum spark table for modifying. This is from a bone stock Solstice GXP. So, I wouldn't copy the numbers. The upper left is a main spark table. The upper right is an optimum spark table (assume all four MS tables are the same and same for all four OS tables). The bottom table is the optimum spark table with the main spark table subtracted from it. Notice how all the numbers on the left are negative while all the numbers on the right are positive? Stock tune is all over the place in a lot of areas. But, what this is telling the rest of the tune is that, when you are below 100% load, take your time because the driver is in no rush to go anywhere regardless of rpm. Also, note how they use the optimum spark table to limit power where the turbo spools up (2-3k rpm). This is more unofficial torque management by dumbing down the boost ramp up. This is also why you have to go a little crazy on other tables to indirectly get the boost ramp response you want.

    OS table.png
    Last edited by codename Bil Doe; 04-03-2014 at 09:05 PM.

  6. #6
    Tuner in Training 08VRSS's Avatar
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    Ah, now i see. I always thought it was more of a spark add in advance kind of table not an "urgency table". That explains a lot. Thank you guys, now I will be spending a bunch of hours dialing in my tune again with the new knowledge of the PID tables and this. I'm trying to control the boost ramp of the ZFR on my setup, prop gain is at .070, and my PID tables are very far from stock. I've got the spool exactly where i want it, but always room for improvement. 22 psi by 3400 rpms (but doesn't come in like a ton of bricks, very smooth and linear), 4500 starts to ramp up to 25psi by 4800 - redline. I have it dialed in so there is literally a .5 psi overshoot but thats it and it settles in at target and holds solid. My goal is to make my setup spool slower lol, quite opposite i suppose of what everyone else is after, but I am after traction, and want my swapped LSJ 4.05 tranny to last awhile. So far so good, I'll chime in with my findings as well.
    Last edited by 08VRSS; 04-04-2014 at 10:33 AM.
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  7. #7
    This should also help people see why making changes to the main spark, alone, can have big unintended consequences to throttle response. If you add 5° to a cell in the main spark without using the above method to keep the optimum spark unchanged, you've now reduced the difference between the MS and OS in that one cell by 5°. It would be the equivalent of subtracting 5° from that cell in the OS causing the ecm to have less urgency and be more sluggish, delay boost, etc.

    Personally, I recommend making this table a single value. It is another table that will help make pedal response linear. Setting this table to where you are happy will require you to go back and make adjustments to other more minor urgency tables.

    SIDE NOTE: Don't forget to correct the 600 rpm row in the main spark tables and change it to 800 rpm to match the optimum spark tables.

  8. #8
    Tuner in Training 08VRSS's Avatar
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    I honestly just adjusted my optimum spark tables the way you mentioned, maintaining the stock difference in the tables. And now i can see why there was differences in my tunes. So you'd definitely suggest just using a single value in the entire table over keeping the stock difference? Is this solely for a linear pedal feel or are there any other advantages? Could you suggest a starting value perhaps if this is what you suggest? Or should i just take an average of the table and apply to all cells?
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    PICK TWO: CHEAP, FAST, RELIABLE

  9. #9
    Safe test scenarios are listed above to give you a feel of how the tables work. Your final values will be where you feel you get good enough response. Different for everyone.

    I have tried multiple scenarios including ramping. I suggest a single value across the board for this table and your PID's. The car will have much better part throttle control while maintaining fast boost response with a single value. The reason is because every position of the pedal will be treated with equal priority. Ramping this table (as it is stock) makes the pedal exponential in feel. Makes rolling on the throttle very difficult to control in a boosted car. I've tested all these scenarios on (road racing) track. Exponential response is great for drag racing, only. It's terrible for mid-corner throttle control, driving around town, leaving a light, merging onto the freeway, etc.

  10. #10
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    I know Bill mentioned not wanting to post up direct numbers but I wanted to share where I'm at with mine after having subtracted MS from the OS.

    Since I was after more response in DD conditions, I was able to utilize a single value in most regions involving drive-ability. Modded on the left and stock on the right. Mine is going to look a bit soft in 'urgency' in the high RPM/high load areas but with how I have my CAL setup, it works perfectly for me with regard to response time and how quickly I build boost.

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  11. #11
    A good point on what T-Man posted. ALL THESE TABLES ARE INTERRELATED. This means it's not like an LS pcm where you can make one change and be good. What works for me on one table will not work for you if that's the only table you change. I have every single table modified for a linear approach, AND they work in conjunction with each other. T-Man's other tables are different than mine, he's looking for a specific response. Therefore, his tables are modded specifically to work in conjunction with each other. There is more than one path to the end result.

  12. #12
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    T-Man and Bill are correct. I just wanted to add that it will also depend on what your goals are. I know I know we already know that Mike is what your all going to say. What I mean by that is just remember from what Bill is saying is the tables all work together which means you can't just make one drastic change to a table and expect results from it that your expecting when another table or tables will affect it. With that being said, instead of one drastic change to one table you might have to make several mediocre changes to 2 or more tables to get the expected result you are looking for while keeping the rest of the tune set up the way you wanted. Sometimes its as easy as change a table and be done, and sometimes its not. I feel like that was way too much typing for such an easy point.

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    Before knowing this.. I did something entirely different from you guys.. Now I'm a little confused if I should change it or not lol.. It seems to run fine although it can spool too quickly at part throttle sometimes. I basically made my own tables from scratch designed for smoothness and ramping... I created both the MS and OS tables from scratch because there was more and more whiskey throttle so to speak with more and more mods added to the car so I decided to do something about it. This is what I came up with, albeit not perfect, but it's pretty good for the most part.
    Screenshot 2014-04-07 11.14.46.pngScreenshot 2014-04-07 11.14.58.png

    After doing the subtract thing that you guys were talking about, it came out a little odd as you can see here:

    Screenshot 2014-04-07 11.21.21.pngScreenshot 2014-04-07 11.21.26.png

    I'd like to know your thoughts.. and it does misfire sometimes down low, but it's not very common anymore.. I've done a lot of work to get this thing to run decently under normal light driving conditions. I also have a ported head and the cat warmup is disabled and it's successful.. not perfect but it does idle just fine down there as long as you don't go revving the engine before the coolant is above 135º F at which point, you're ok to drive. Revving it at low operating temperatures will cause it sound like a misfire but Iirc, there aren't any showing up on the scanner. I basically got it close enough that I quit playing with it down there and then went to work on getting driveability up to my satisfaction. Still not 100%, but it's pretty damn good. And as you all say, this is for my car only lol.. Based on my tables, I did 2 other tunes on other pplz cars.. 1 worked with cat warmup deleted, and the other did not. Seems as though every car has to literally be custom tuned specifically for that issue. Anyways....
    LMK your thoughts.
    Thanks

  14. #14
    I'm guessing with that timing up top you're running E85 or 110 octane? What is your optimum torque table? PID's? turbo? mods? cam tables? etc. There are others I've forgotten to mention that need to be viewed (iow whole log not just two tables). All the tables play together. Have to see a whole tune (log helps, too) to get better idea of all the tables together.

    Cobaltssoverbooster has the most knowledge on ported heads.

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    Virtually every table has been modified lol And I just changed my OS according to what you guys have mentioned in this thread and I think I may have gained a bit more improvement However, down low I gained some KR so I'm guessing it needs to be reduced between 30 and 60 load up to 2700 rpm; I was thinking it needed more instead of less, but it's kind of a crap shoot as to what's needed where.. good ol trial n error.

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    Again other tables will affect it especially KR. You can create KR from a lot of other tables other then the spark tables.

  17. #17
    You can also create a lot of kr if you don't have every table very smooth. I hand smooth. Takes a lot longer, but worth it in results.

  18. #18
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    now after you set the entire os table to a single number i chose 36 it runs great! but i have question down in low loads cruising area lets say 2500 to 3500. if you do the right click subtract to the os tables like we were told now they are negatives.. is this going to effect anything?
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  20. #20
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    Did you set the table to 36? If that's the case then you misread what to do. You should have subtracted the stock spark table from the stock optimum spark table to get an understanding of the tables. When I posted earlier to pick a number for the whole table you were supposed to add the spark table to it. I would start of small. 36 is too high.