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Thread: Slight idle/rolling surge

  1. #1
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    Slight idle/rolling surge

    Hello all, 1st post here

    New to the tuning game and been reading around on here to gather as much knowledge and info as I can. Reason I come to you guys today is that I am trying to track down and eliminate a small idle surge issue.

    Little rundown, back in fall of last year I upgraded my cam from the previous small cam to another "smaller slightly larger" cam. Everything went great and ran awesome for a small cam car. Fast forward to around 1st of the year and started having some issues, fought and fought with tuning and inspecting things to finally find out basically had blown both head gaskets. So now that everything is back together and running, I am having an issue with the idle and best way to describe it is that at idle only when car is 1st started and warming up, the rpm's will climb to around 1200 to 1300 rpm when clutch is pushed in during a rolling stop. Also it will idle great and not fluctuate at all when good and warm, until the a/c or heat is actually running, then it will surge, but only when clutch is pushed in and car is moving, then it will idle good when car has come to complete stop. Any idea's what to look for to possibly adjust/correct these slight issues? Current cam specs are 226/232 .58*/.57* 112lsa. Basic bolt on modded 2010 SS w/ 2in LTH and no cats. Hand port/polished heads. Attached couple of logs and tune files. I hope it works.

    Thanks in advance
    Attached Files Attached Files

  2. #2
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    Can you add the following and log again;
    Dynamic air flow
    Minimum idle air flow
    Cylinder air
    Desired rpm

    Your adaptive spark in gear is not helping to pull timing out to try and get the engine speed down. And your throttle follower step up is a long way from stock.

    For fault finding; put all your adaptive spark settings (P/N, Gear & Coast for both over and under speed) & throttle follower step up back to stock and start from there.
    Attached Files Attached Files

  3. #3
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    Ok so I added All the above items except the minimum idle air. I cant seem to find that one, even when trying search feature. I will work on changes and retune, then perform a new log tomorrow on the work drive.

    Thanks for the help

  4. #4
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    Well I retuned with the adaptive spark changes and done a quick parking lot low rpm drive ,and never felt anything or noticed the surge, but as I was typing this fixing to add the data log, it hit me that I didn't have the A/C on, which is normally where issue occurs. I will still post the log with the addition of the parameters you were wanting logged, but I will also post another when I arrive home from work. Sorry about that.
    Attached Files Attached Files

  5. #5
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    I can see the adaptive spark working hard to bring the idle down to desired in a few spots. For example your commanded spark is 20 but your adaptive spark is driving you down into 10 etc. That usually means your minimum air is a little to high (assuming your engine is air tight, I.e. vac leaks etc).

    I have taken out a smidge from the 800 and 1000rpm columns. Your idle fuel trims could also do with a tidy up. Search Goat Rope Garage on you tube for dialling in fuel trims using STFT + LTFT. He has some really good videos to get you into it.

    The easiest way I find to tell if minimum air is to high without a laptop hooked up, is when idling, every so gently and very quickly try and brush the throttle with your foot. Just enough so it registers a couple of percent. If the revs hang up like +50rpm or more for about 3-4s seconds then drop you know your minimum air is too high.
    Attached Files Attached Files

  6. #6
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    Well, hooked up laptop this morning for the drive to work, started logging and my commute only takes around 8-15mins depending on traffic, and all was going great but soon as I started to exit turning lane into the parking lot, laptop craps out on me. Needless to say data log lost, but I can say that the changes did help. Didn't have the surging that I was seeing before, just curious to see if it continues. I noticed as I was logging though, that my STFT B1 was not logging and remained flat-lined the entire time??

    I have been watching as many video's as I can in my free time for further training and learning. You would think being able to repair and program CNC's, Lathe's, and Robots, that this would be a breeze, but I guess just like it was when I started on those items 15yrs ago, there is so much to learn, and it seems to have new things added everyday. I really appreciate the support so far, and I am eager to learn how all this stuff works.

  7. #7
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    Your 02 sensors are doing there thing as are the STFT's.

    You do have LTFT disabled. [ECM] 2502 LTFT MIN ECT is set high to disable long term trims.

    A good thing you can do is grab a stock tune from the repository that matches your vehicle (if you haven't already) and run the compare function to see what changes have been made from stock. Then research why those changes were made. It's a good way to bed in some of the learning curve.

    3_Fuel Trims.PNG

  8. #8
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    Hjtrbo,

    Thanks for help. I actually have browsed around with the compare function and noticed the changes between the 2 tunes. I noticed the difference there, but just wasn't sure on why they were disabled. As for the STFT B1 not logging yesterday morning, must have been a glitch possibly during the re-flash?? After adjusting the Min Air table to match what you had done, and doing another flash, I done a data log while leaving work and it was working and logging again. New log attached below.
    Attached Files Attached Files

  9. #9
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    If you want to learn some basic tuning read on. If not, call what have you good and enjoy it when the sun is out!

    ...

    You are in the ball park with idle now so you can put spark & min air flow to the side for now and move on to the next things...

    Ultimately you want to get to the idle tuning procedure that BigMike42 put together. But there is no point in running through that procedure until your fuel trims are in order. The reason is that when you tidy up the fuel trims (in your case rich at idle) you will find that the reported air flow will change (lower for you), which will then throw out what you worked out with the idle tuning procedure.

    Add the following channels to your scanner if available:
    • Fuel trim cell (Can tell you if you are in idle, coast, run, PE, open loop, DFCO etc etc, a very helpful tuning parameter)
    • Idle adapt advance (Handy quick reference for idle settings health)
    • Engine torque (Used to update throttle follower table)
    • Mass air flow (Hz)

    First:
    *You are MAF only in your tune but it is good practice to update the VVE table also. Don't use cruise control as your throttle pedal movements are required so they can be used as a filter.
    https://www.youtube.com/watch?v=kaRL...GoatRopeGarage

    If this is your first time mucking around with this stuff (it was for me not long ago) just start with a log in your drive way from cold to hot, make the changes you think are right to the MAF and VVE tables and post your proposed tune here for a sanity check before you load it into the car.

    **He is using a wideband so he can do full throttle, you won't be able to do that with STFT tuning. Buy a wideband.
    https://www.youtube.com/watch?v=8gum...GoatRopeGarage

    Second:
    https://forum.hptuners.com/showthrea...e-tuning-guide

    Your VVE table log results are typical of a stock table that has a cam added. See how poor it is at low rpm / cylinder air (rich, less air getting to cylinder, dirty pig of a thing) , then as you get a move on it leans out (more air getting to the cylinder, bigger bang, mo powa)
    3_VVE Table.PNG

  10. #10
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    Hjtrbo, again thanks for the info. As stated, definately looking to hone in the skills to do this stuff. With all things though, I know it just takes a little time, and I have actually been reading of BigMike's post for last couple of weeks back and fourth and taking it in. I also already have an AEM WB, but dont have it hooked up at the moment due to staying stuck at 14.7, so I was thinking something is wrong with it. Went thru the troubleshooting methods for it to test and it seems to be working according to AEM, but not sure, so just removed it due to pod getting damaged anyway. I will have a little more time to play with it this weekend, so I'll dabble with the items provided and report back to the post. Many thanks again.

  11. #11
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    Hj,

    So I re-enabled my LTFT, and after doing some more Goat Rope video watching, and pouring thru, then back thru BigMikes's post, I decided to log a little and compare my VVE table to what I collected on my data. I attached a picture of the current (tuned before I started learning) to what I logged and corrected. I have not loaded this to the car, just curious if this is how this task is performed or not? Am I correct in my work on this and making changes, or do I need to study some more? And again, I cannot say thank you enough for the help.
    Last edited by Black Plague; 10-26-2020 at 01:02 PM.

  12. #12
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    You got plenty of cell hits. Well done. If you aren't already remember to interpolate in between cells that are missed and blend out to the zone boundaries. There's a nasty bump in your table which should disappear during the tuning journey.

    Did you switch over to VVE only mode only to get that log??? I.e. disable MAF etc. I left your VVE table alone till you get back to me. But here is an updated MAF curve for you based on your log which will be accurate as the dynamic air was tracking the MAF nicely in the areas that are allowed past the filter.

    Get that wideband going man. And remember you must reset your fuel trims every time you change MAF or VVE tables.

    Can you add engine run time, volumetric efficiency airflow, volumetric efficiency and manifold (or intake) air temp to your next log please.

    There are some real smart people out there. Can do MAF and VVE at the same time as per: https://forum.hptuners.com/showthrea...ation-for-gen4. I recently started using this myself and it is pretty good. I've got the chart and formula for you in the attachments.
    Attached Files Attached Files
    Last edited by hjtrbo; 10-27-2020 at 02:08 AM.

  13. #13
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    HJ,

    Good deal. I actually cant remember if I am MAF only still in the tune, or if I have it disabled at all. Pretty sure I wasn't VVE only though, as I still need to research how to do that. I will have to doublecheck all that. Just done that to see if I was on the right track. Bad thing is, laptop crapped out on me completely, so I am shopping for a replacement. Once I'm back in the game, I'll get back on it and play around some more. Once again, I can't thank you enough for the help.

  14. #14
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    No worries man, I have been getting helped by another forum member on here who has been nothing short of awesome to me. He knows who he is if he reads this post. So I figured I'd do the same. I'm learning too, so I will only be able to help you get so far. But that is what this forum is for. Once I hit my limit with you I will openly admit it and hopefully you can get further help from the others

    You are definitely MAF only. To re-enable your VVE you set your RPM enable / disable values higher. I'll leave it up to you if you want to re-enable it or not. My personal opinion is leave it active. While you're waiting for that new laptop there are some very good posts on VVE here, worth digging through to help you decide. The consensus is dynamic throttle response is better with VVE enabled from how I have interpreted the information.

    Your current VVE tables are very close to stock. Based on the changes to your MAF so far, all I would do is multiply VVE Manifold switch open / closed tables by 10% and then hit calc co-efficients.

    And take it easy on the power runs until your wideband is up and running unless you know where your fuelling is at up top.

    4_VVE Only.PNG
    Last edited by hjtrbo; 10-28-2020 at 11:04 PM.

  15. #15
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    Back in the game finally. So I have reenabled my VVE, added the requested fields, and done 2 logs. One log is drive to work, so early morning weather here in GA was down around the high 30's to low 40's. Then the drive home log was afternoon log with say temps in 60's to 70's. Also on the attachments from the last adjustment, I cant get those to open to view the information. I see they are xsel files, which I have on my laptop, but also couldnt open on old laptop wither. Anyway. I have not made any changes in my tune yet, as I want to go back thru my information and just make sure I am doing everything correctly. Life's been fast and crazy out my way, so kinda lost time in my training and research.
    Attached Files Attached Files

  16. #16
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    Add this to your math parameters. Delete the old one if you added it as it was looking for manifold air temp which you don't have.
    GMVE STFT % Error From MAF_Black Plague.MathParameter.xml

    In your graph tab on the scanner, right click anywhere and select graph layout. Up top of the new window that pops open, click the folder icon. Add these 2 graphs.
    GMVE_LTFT + STFT.Table.xml
    MAF_LTFT + STFT.Table.xml

    Add a new Chart vs Time to your scanner. As above, right click anywhere, delete all the groups, then click open and add this layout to it.
    Chart vs Time Layout.Charts.xml

    With your MAF curve, your last cell hit is 6000Hz. What I would do for safeties sake is grab every cell above that and multiply them by 1.01 multiple times until the curve blends in with the 6000Hz cell. The reason this is done, is the pattern shows you are lean in the mid range, so a cautious assumption is made that the lean condition will continue up the MAF curve. Obviously once your wideband is up and running these upper cells can be dialled in.

    Same with the VVE table, probs needs 10%ish added up top as a starting point. And again, needs 20%ish taken off at the bottom. Blend and smooth
    5_VVE Table.png

    I combined your log files so you have more data in the one log.
    5_Work + Home Drive Combined Log 11_4_2020.hpl

    Not going to spoon feed your tune back to you , see how you go with it. As per the Goat Rope videos, copy and multiply by percentage half. Then blend / smooth as needed.
    Last edited by hjtrbo; 11-05-2020 at 07:17 PM.

  17. #17
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    No sir, not looking to be fed at all, I hate those mashed up, jarred veggies just as much as most infants do. I am just after constructive criticism on how not to F__k my engine up, thats why I am slow to respond on some of this. I am researching the items that I am changing, and learning why the changes are required. Hell it took me a day just to find that VVE table to modify it. LOL. As stated several times already, I truely appreciate the guidance, and hope that I to can help someone out. I will play around with this info and make the changes to my VVE table with the data logs I have gathered and post up a clip of the changes in couple weeks. Weekend is booked up, and weekdays are hectic, so be a little while before I get to do a whole lot.

    I also see that with the combined LTFT+STFT files that you combined, does it reports both on the same chart? I had been wondering if I was using the correct trims when playing with the VVE table. I had used both of them separately to tune VVE before my laptop crapped on me, and wasn't able to save the differences, if there were any.
    Last edited by Black Plague; 11-06-2020 at 11:38 AM.

  18. #18
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    Yeah, the combined combined LTFT + STFT is a parameter that can be selected to be displayed in your charts and graphs. It takes the average of both banks respective LTFT and STFT and then adds them. It's a handy parameter.

    In the graphs I gave you, try and learn the filter I used. Feel free to adapt it to see what it looks at. A good tip is to create a math parameter of that same filter and add it to your chart so you can see when the filter = 1, I.e. letting data into your graph. Your car is more forgiving with throttle movements than mine, so you could choose to loosen up the throttle part of the filter. The goal is to not allow the large fuelling swings you get with abrupt throttle changes making it into your graph.

  19. #19
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    So I got to do some more logging and tweaking on my VVE table. So on the LTFT+STFT graph that you gave me, when I'm logging it doesn't show any data in the cell. It will show each cell being pinged, but no actual number values. Am i missing something there? I have tried to dig up some info on it, but haven't been able to yet. I'm posting up my VVE adjustment with the several logs that I combined using just LTFT only, and adjusting the ranges by adding 10% and lowering the other values from the graph picture you provided. Just let me know if I am kinda close on my adjustments, or if I need to think on it some more. Don't have to make any changes for me, just wanna see if I'm going in a good direction.
    Attached Files Attached Files
    Last edited by Black Plague; 11-13-2020 at 08:28 PM.

  20. #20
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    In that tune you have attached, the MAF is set to fail. The GMVE formula I gave you relies on having the MAF enabled. Tuning MAF and VVE separately is no longer required as per the thread I linked you to in post 12.

    If you did have the MAF failed I would start again. If MAF was not disabled for the logs you attached, then all good.

    Not sure why your VVE graph wasn't working. I double checked with your logs and it is working at my end. When you open the GMVE graph, you might have to reselect the math parameter, try that before importing the attached items parameters / graph / layout below.
    GMVE LTFT + STFT % Error From MAF_Black Plague.MathParameter.xml
    GMVE_LTFT + STFT.Table.xml
    Black Plague_General Layout.Layout.xml

    Your adjusted MAF curve looks very nice, you've smoothed out the bumps that can come from the adjustments sometimes. Nice. Your VVE table will come to you as you progress. You are doing the fundamentals well. Smooth driving, multiplying by half, interpolate / extrapolate / smoothing. Make sure you understand the filter I gave you. Filtering is a very powerful addition to the scanner and highly worth mastering.

    Keep it up...
    Last edited by hjtrbo; 11-13-2020 at 09:07 PM.