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Thread: About to throw in the towel nailing down idle

  1. #301
    the part I struggle with is understanding why to subtract 20% after you've found your min airflow number, wouldn't that be it.

  2. #302
    Senior Tuner 5_Liter_Eater's Avatar
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    The histogram is logging the average airflow logged in the cell. What we want is the lowest airflow in that cell, but relying on the - function doesn't yield good results. I came up with the 20% just playing with things when developing the process.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
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  3. #303
    does the ecm only use the start up idle table for the amount of time in the table?

    I'm asking because I am running really lean during a cold/overnight startup and wondering if removing air flow in that table will help fix this.

  4. #304
    Senior Tuner 5_Liter_Eater's Avatar
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    Yes but that's just for the first 8 seconds and adjusting airflow there will not have any effect on AFR. Your airflow table is off in that range. A band aid you could use is to command richer at lower ECT's via the open loop EQ ratio table in the lower ECT's.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  5. #305
    By airflow table I assume you mean VE or MAF table? It stays lean for 3 mins and then goes good and it's all in the same table range

    Didn't think about the OL EQ table but agree that's a band aid and not the right way to fix. Thanks

    Quote Originally Posted by 5_Liter_Eater View Post
    Yes but that's just for the first 8 seconds and adjusting airflow there will not have any effect on AFR. Your airflow table is off in that range. A band aid you could use is to command richer at lower ECT's via the open loop EQ ratio table in the lower ECT's.

  6. #306
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    You might want to "tweak" you colder temp injector timing. Have had to help a few people out having this same issue after cams and or blowers were added to their vehicles then tuned by other shops.

    Just a thought...
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  7. #307
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    Quote Originally Posted by edge04 View Post
    By airflow table I assume you mean VE or MAF table? It stays lean for 3 mins and then goes good and it's all in the same table range

    Didn't think about the OL EQ table but agree that's a band aid and not the right way to fix. Thanks
    What do fuel trims look like during the 3 minute period and what do they do after that?
    Post a log and tune if you want help

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  8. #308
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    What I struggle with most on GEN V cars is definitely idle. I have had cars go smoothly and idle like a champ in all situations and then turn around and have one give me fits. I had one recently that I could flash it and it would idle and drive like a dream. Go drive it and then out of the blue it would start surging again at idle with everything else being great. Change airflow again... good at first. 30 minutes later back to square one. Same thing over and over. That car drove me up the wall...
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  9. #309
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    Quote Originally Posted by 5_Liter_Eater View Post
    ***Updated for clarity and added CFCO recommendation 7/18/12***

    - I suggest leaving the idle adaptive spark control overspeed and underspeed tables and adaptive idle proportional and integral tables as they come stock.
    Hi,

    I cant see any of the mentioned tune tables that people say they attached,how do I get them?
    I have a GTO LS2 manual, and a stock GTO tune map would really help me.
    The car has had a stroker kit put in, ported heads with bigger valves and lumpy high lift cam and long extractors added, and they tuned the ECU to that.

    Now ive removed the cam, kept the stroker many tunings changed and ive managed to tune the main AF ok, but the cold and hot start up still sux.

    My problem is when you say leave "setting X" stock, I dont know what stock is and its probably not what is currently set in this ECU.

    Even a corvette LS2 manual map wont be too far off.
    Last edited by HoldenTuner; 08-21-2017 at 08:27 AM.

  10. #310
    Senior Tuner 5_Liter_Eater's Avatar
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    The process was developed for the old version of HPT and I have no plans to update them as I've sold the car and cable. I believe someone else came up with their own gen 4 idle tuning process though.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  11. #311
    Hey guys,

    I'm new to the whole HPT stuff, far more familiar with tuning using a 9/16" and a flat head, anyways I'm just here trying to learn as I go. I'm not sure if I missed something or if this is a stupid question but I've seen it a few times in the post where people are referring to specific histograms, is there a place where we have access to all the different histograms for different applications or anything like that? Like i said I'm pretty new at this and have only done pretty basic stuff so far and just trying to get use to all this computer stuff.

    Forgive me if this is a stupid question, figured it doesn't hurt to ask though. I stumbled on this thread because my LY6 that I swapped into my Cutlass hangs a bit when I get off the throttle. It's nothing major, just a bit annoying.

  12. #312
    Senior Tuner 5_Liter_Eater's Avatar
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    Again the configs and histograms in this thread are obsolete. Here's another thread about it:

    https://www.hptuners.com/forum/showt...e-tuning-guide
    Last edited by 5_Liter_Eater; 10-10-2017 at 10:42 AM.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  13. #313
    Even though the configs are out of date, the procedure for getting the base running airflow, or at least a close approximation of it should still work correct? Like would zeroing out the table and then setting up a histogram to plot mass air flow rate against rpm still give the correct data? Then take those numbers, subtract 20%, and put those numbers in the base running airflow table. Without doing this, it is just a very general ballpark figure that people enter in the table after a cam swap if my thoughts are correct.

  14. #314
    Thanks 5_Liter_Eater. Really appreciate it.

  15. #315
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    couple questions if u have time. I have a 07 tbss its a 432 ls3 has cbm heads and a 630/613lift 112ls and 236/250 dura cam, 42flex fuels and stock tb and intake. idle was never perfect from the first time I had it tuned and it quit making power at 5300rpm. tuner said it needed more air. So before I finsh this turbo kit I figured Id buy a intake and throttle body for these cathedral port heads and try my luck tuning it since i have hpt and needed to know more. put a nw 102 ls7 maf and holley hi ram. now it starts up and idles at 2500+ and itll come down to 950 after a little time but then driving it wants to hang on to higher rpms after I let out of it. Any help would be great ive gone through and changed a lot to not have anything that seemed to help>

  16. #316
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    Quote Originally Posted by rettig View Post
    couple questions if u have time. I have a 07 tbss its a 432 ls3 has cbm heads and a 630/613lift 112ls and 236/250 dura cam, 42flex fuels and stock tb and intake. idle was never perfect from the first time I had it tuned and it quit making power at 5300rpm. tuner said it needed more air. So before I finsh this turbo kit I figured Id buy a intake and throttle body for these cathedral port heads and try my luck tuning it since i have hpt and needed to know more. put a nw 102 ls7 maf and holley hi ram. now it starts up and idles at 2500+ and itll come down to 950 after a little time but then driving it wants to hang on to higher rpms after I let out of it. Any help would be great ive gone through and changed a lot to not have anything that seemed to help>
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  17. #317
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    ill take some of your idle secrets for a e38 gen 4 lol

  18. #318
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    Quote Originally Posted by rodstrong0 View Post
    ill take some of your idle secrets for a e38 gen 4 lol
    i used the tricks discussed earlier in this thread along with a video i found on youtube https://www.youtube.com/watch?v=FW6oM2qY9g8
    i started from there and got my LS7 idling better. last thing i need to do is fix my high idle hang when coasting.