Results 1 to 11 of 11

Thread: LNF Idle

  1. #1
    Advanced Tuner
    Join Date
    Sep 2007
    Posts
    457

    LNF Idle

    So you will notice I posted a picture that includes a ton of tables, and all of these affect idle. In fact I forgot to add a table. I recommend raising the idle cell fuel pressure up to 400psi from the stock 218psi. The numbers listed in the main pic is of a tune I have used in the past, and that was all of the idle stuff I used (minus the MAF calibration, and little things like that). I would highly recommend looking over all of the tables I posted in the main pic, and compare them to your stock tune, and your own tune.

    I also posted a pic of a Spark Table I have used in the past as well. You will notice that it is one continuous flow. Unlike stock tunes, and unlike most peoples tunes, you will notice that the idle cells flow right into the next set of cells. This will actually help out with the initial throttle KR that people tend to see.

    I also want to point out another big thing. I posted a pic of the stock Wastegate DC table. Compare that to what I posted in the main pic. Notice the differences? Adjusting the column axis can actually affect idle A LOT. Also placing a set of numbers instead of all 0's in the first column will actually change idle A LOT as well.

    This write-up is intentionally left vague, so that way people ask questions and I can gear the answers towards that. It would take me a week to try and think of every outcome I could try to come up with on how all of these tables affect idle. Depending on your setup, and how you have your tune setup, would depend on what I would recommend on what you should do for your idle tables.




    *****IMPORTANT******
    When you are tuning idle other then the stock method, you have to keep in mind that it gets very touchy. What do I mean by this? You are tuning idle to your exact setup, and to your exact area. Changing these things WILL mess with the idle. Also keep in mind that other changes to the car that you did not intentionally do will change idle as well. What does that include. Things like a MAF getting dirty, Throttle Body getting dirty, or other sensors not working properly. Etc., Etc.


    Idle Tables.jpg

    Spark Table.jpg

    Stock Duty Cycle.jpg

  2. #2
    Advanced Tuner
    Join Date
    Sep 2007
    Posts
    457
    You guys will also notice how timing is raised in the low rpm high load areas. Including the low rpm low load areas. Another reason for doing this, is because if you hit these cells you can end up having too low of a spark and it'll cause it too hunt in those spots. Negative timing is not really a good thing. I usually only see issues with the autos when it comes to low rpm low load hitting weird cells, but it also happens if the person who is being tuned can't properly take off in a manual and properly throttle and feather the clutch. Timing is a huge thing, so keep that in mind when you are tuning.

  3. #3
    ok how do you go about adjusting them from stock? Any thing in particular that needs logged? Or is done by feel

  4. #4
    Advanced Tuner
    Join Date
    Sep 2007
    Posts
    457
    Mostly feel, but you need to log it to know if it is correct and perfect.

  5. #5
    ok so do any of the tables correspond to anything in particular?

  6. #6
    Tuner in Training
    Join Date
    Dec 2012
    Posts
    21
    17-01-24 06-40-13.hpl

    I have an idle question. I have a log of a cold start. the first 5 seconds or so it ran rough, then smoothed out and I got 3 degrees or so advance. much better than what I've been getting where it would jump from 21 to -5 to 15 to 12 to -4... but im still not getting the commanded value in my spark tables which is much higher. do I need to increase the DAL values in my idle areas?

    and Mike, I looked around to try and find the idle cell for fuel pressure to increase to 400 from 218 but I cannot find it. do you remember where that little guy is hiding?
    02 ws6-nitrous,intake
    99 gsx,880 injectors,eboost 2,lc-1,evo9 fuel pump,hard pipes,self tuned,17psi
    09 cobalt ss- LHU swap w/LHU manifolds & injectors,intercooler & pipes,3" dp,K&N intake,3 bars,hp tuned-ish
    02 softail-se204 cams,intake,VH exhaust,carb rejet

  7. #7
    Advanced Tuner
    Join Date
    Feb 2010
    Location
    The Desert
    Posts
    480
    Quote Originally Posted by FLASH1970 View Post
    17-01-24 06-40-13.hpl

    I have an idle question. I have a log of a cold start. the first 5 seconds or so it ran rough, then smoothed out and I got 3 degrees or so advance. much better than what I've been getting where it would jump from 21 to -5 to 15 to 12 to -4... but im still not getting the commanded value in my spark tables which is much higher. do I need to increase the DAL values in my idle areas?

    and Mike, I looked around to try and find the idle cell for fuel pressure to increase to 400 from 218 but I cannot find it. do you remember where that little guy is hiding?
    Play with adding or subtracting minimal amounts from your DAL idle area. Every setup is different.

    Go to your fuel system tab - Pressure Limits - Pressure min and adjust. Then go to your "normal" fuel pressure tab and adjust to match in the idle area
    09 RY Cobalt SS Coupe - 19K miles - Bolt ons + 7163 ZFR, HP tuned on ethanol

    Sold - 09 SRTC Cobalt SS Sedan
    Totaled - 09 VR Cobalt SS Sedan
    Sold - 09 RY Cobalt SS Sedan

  8. #8
    Potential Tuner
    Join Date
    Aug 2019
    Posts
    2
    Bringing this thread back from the dead.

    I recently bought a previously 'tuned' LNF and noticed my idle to be crap!

    I've done some logging and my spark is all over the place. I've done a lot of reading on Spark, Opti Spark, and a lot of the other Torque based articles on the E69. Just not sure where to start.

    190907 Tune v1.5 - Cold Start.hpl
    Cobalt v1.5.hpt

    I also have a lot of KR events on tip in at idle, seems to be a common problem.

    If anyone wants to look at my log/tune and point me in a directions to start looking to get this thing smooth, I would appreciate it!

  9. #9
    Tuner
    Join Date
    May 2014
    Location
    Metro Detroit
    Posts
    119
    What are all the hardware modifications to the car?

    I bet the car will run better with stock spark and opti-spark tables.
    Whoever did the tune smoothed out the spark table, but not the opti-spark table.
    One (oversimplified) way to look at it, is that the surface that is generated if you subract the spark and opti-spark tables should also be a smooth surface. dont have my tune on this laptop so can't tell you how far off you are from a smooth idle.

    Also, beyond the rolling idle, the slow oscillation in rpm at the beginning of the file. Even at the end of the file when it's warm, does it just kind of ... vibrate, kind of like a harsh vibrating idle, like you can feel and hear every combustion event? if so, let me know if you want to fix that.

  10. #10
    Potential Tuner
    Join Date
    Aug 2019
    Posts
    2
    Hi TurboCobalt,

    Mods are as follow: K&N Intake, Injen Charge Pipe, 3" catless DP to straight pipe (1 resonator), 3 bar map sensors, Hahn Intercooler, HKS blow off valve (stock bypass valve is bypassed).
    All mods came with the car at purchase.

    I've since made lots of changes to the tune including smoothing out the opti-spark table based on some other threads I've read.

    The car is running a lot better up top and I've made a few small changes, the cold start idles are the worst however.

    Cobalt v2.4 - Smoothed Timing.hpt
    191108 Tune 2.4 - Cold Start.hpl

    If you look at this cold start log from this morning, it's almost seems that the car wants to die and drops RPM until it's warm. I've noticed that if I very slightly engage the throttle pedal everything is buttery smooth (~1050 RPM, ~10% throttle, perfect idle timing in the 20s). So maybe I need to adjust the commanded throttle at idle? Not exactly sure the method of doing so.

    Your last line is a perfect description of what's happening, a lot of vibration and such. The timing has a sawblade pattern until very little input is added to the throttle, like I mentioned above.

  11. #11
    Tuner
    Join Date
    May 2014
    Location
    Metro Detroit
    Posts
    119
    I had the same problem with cold starts.
    Here's the advice i got from this forum and it worked for me.
    -first make sure your MAF table is as accurate as possible, personally i prefer to set table 13600 to all 1, and tune table 12600. focus on being accurate between 2500 to 4000 Hz.
    - second work on your spark and optimum spark tables in this area, 800 to 1500 rpm; 20 to 40% load. Focus on the relationship between the 2. for example take your spark table and subract it from the optimum spark table, and make sure that difference is uniform; for example at 800rpm, 40% air load your optimum spark is too low, bump up the optimum spark by about 3 to 4 degrees and see if that helps.

    Alternatively you could use stock values in this low load, low rpm regions and it would fix your cold start.


    just cause im curious i looked at the rest of your tune; and i don't think your table 33420 (Airflow>>Turbocharger>> Wastegate duty cycle) is correct. if you have a stock turbo, this should be roughly stock values. Not sure how you are not having boost control problems with the values you are using.
    i prefer to keep this table around stock, and control my desired boost using the Mas Air Load Torque (table 12833) and the boost limit "pressure RPM factor" (table 33445) and maximum pressure limit (value 33451)