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Thread: e38 tuning gen 6 bbc help

  1. #1
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    e38 tuning gen 6 bbc help

    I am working on e38 ecu swapped gmt400 big block truck. I have a tune that is working, but has drive ability issues. So far, I been trying to continuously go over the engine it self trying to verify and weed out any mechanical issues but still seem to be somewhat stuck with following:
    Surging cold start up idle
    Hesitation on throttle when cold and when hot. Runs better when lightly warm
    Highway driving specifically seem to be poor performance
    On full or close to full throttle application, wide band reads output as lean initially and then ramps to commanded AFR.
    Was looking for some ideas on what should I be looking in to or if something being missed that might be obvious just looking at the run screen shot.
    I am almost thinking of getting a single plane efi style intake manifold and try with it instead.

    Engine is 488ci, brodix oval port RR heads, cam is HR73353-114 233/233 @.050" .353"/.353" Lobe Lift .600"/.600" Valve Lift 114 LSA, shorty headers, 1000cc FIC injectors, stock 454 vortec intake manifold lightly ported, ported throttle body inlet with LS3 throttle body, ls1 coil packs, ls3 maf, stock cool air box, about 8.9:1 compression. Injectors are large for future expansion.

    Edit: IS301-1000H fuel injector clinic
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    Last edited by yevgenievich; 09-25-2022 at 05:15 PM.

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    Tuning Addict blindsquirrel's Avatar
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    I'd start with correct injector data (and scaled correctly, too). If there is no data for the injectors you need to toss them.

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    Quote Originally Posted by blindsquirrel View Post
    I'd start with correct injector data (and scaled correctly, too). If there is no data for the injectors you need to toss them.
    tune was scaled, but I did realize after looking over everything just now that not all injector data was updated correctly. Going to go for a drive with corrections added now. Updated tune file in original post

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    Tuning Addict blindsquirrel's Avatar
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    [ECM] 12560 should be halved when doing this type of scaling.

    That's possibly one of the weirdest Offset tables I have ever seen. That data is either not correct or those are some funky injectors.

    Does "FIC" mean FIClinic or FIConnection? What part number? Link to datasheet?

    Timing is probably reeeeeeeeally low. I realize aftermarket BBC chamber will be better than factory, but still. You've got less timing in a lot of the important parts of the table that are less than the 5.3L LMG the OS came from. But I wouldn't bother with that until injector stuff is sorted.

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    Quote Originally Posted by blindsquirrel View Post
    [ECM] 12560 should be halved when doing this type of scaling.

    That's possibly one of the weirdest Offset tables I have ever seen. That data is either not correct or those are some funky injectors.

    Does "FIC" mean FIClinic or FIConnection? What part number? Link to datasheet?

    Timing is probably reeeeeeeeally low. I realize aftermarket BBC chamber will be better than factory, but still. You've got less timing in a lot of the important parts of the table that are less than the 5.3L LMG the OS came from. But I wouldn't bother with that until injector stuff is sorted.
    Thanks for taking a look. Injectors are from clinic IS301-1000H.
    Thank you again for looking at the tune, I will make the correction for scaling. I have only other stock tunes for reference on timing table. I have a turbo that is going, but think should be able to add more advance and then back off when under boost. Is that correct thought process?

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    idle_surge.jpg
    This is the idle surge that happens on startup.

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    Turned out the injector data was still not correct. FIC pointed to the right data to use. Updated that and have two different files with different spark maps to try out tomorrow.
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    After going around in circles turned out I did have the correct injector data to begin with. What was a bit odd is the fuel flow rate vs pressure. As the tune was scaled by %50, and injectors are 100lb/hr at 3 bar. After turning injector flow rate to 110lb/hr for 4 bar system, accounting for vacuum referenced fuel pressure regulator I set the values in the table to 55 for the whole table. On the plus side, now overall cold start does not surge as much and random stalling is less. Still have few stalls, especially in varying transient load scenario(like going over obstacles). It seem to be especially negatively sensitive to 195* coolant temp or greater, or high IAT.
    Also something not sure on how to adjust or if needed to adjust. When cool it currently starts off with positive fuel trims, and as it gets fully warm it goes to very negative fuel trims. Difference from +20 to -20

  9. #9
    Tuning Addict blindsquirrel's Avatar
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    The Offset table has to be flat as well, with a referenced regulator.

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    Quote Originally Posted by blindsquirrel View Post
    The Offset table has to be flat as well, with a referenced regulator.
    Thank you, did not think about that one. Which column (corresponding (kPa)) should be carried out through out the whole table? Would it be 400kPa?
    Actually, this might get a bit more complicated. Is table references voltage for fuel pump or injectors? I am running a pwm fuel pump controller that is map sensor referenced(to boost pump output under boost condition)
    Last edited by yevgenievich; 09-28-2022 at 10:27 PM.

  11. #11
    Tuning Addict blindsquirrel's Avatar
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    If you have 58 psi base, then yes, 400kPa (or 408, depending on early/late ECM) column pasted all the way across.

    Injector voltage.

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    appreciate the help.
    I have couple of things that trying to find. It appears as if when coming off idle, spark advance goes down first then goes up which causes a stumble or delay before actual response to throttle input. That stumble seem to be mostly only present at 195 ect or higher. And then the condition where at lower speeds sometime gets tendency to stall. Also, wondering what is the normal delta in fuel trims in the 185-200 coolant temperature variance.

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    Attaching log and a tune. Timing control is odd, and I have not found what it really should be. Some times it will lock in to 8* of timing for some time, then will go back to normal. Also, tune had the timing set to jump advance on throttle release that I am not sure if needs to be that aggressive. However, I do get occasional stalls on throttle release. Currently high and low octane spark tables are the same.
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    I've done a setup like this with a 502 but with a '411 PCM.

    Have you done much tuning before? This is going to be a pretty advanced job. The 502 and the SBC's I've done like this have all eventually took quite a lot of OL cold tuning.. They run quite a lot dirtier than a LS. So I'd ignore what it does short of fully warmed up for now.

    Make sure the injector data is proper and work on the tune while it is fully warmed up since the cold stuff is just adders on top of that anyway.

    Also I'd probably not use more than 46 degrees advance in decel/low load and at wide open its going to take somewhere between 28ish on the low side but likely low to mid 30's.
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    Thanks for the feedback and advice on timing. I had someone else work most of the tune for me to begin with. One thing I am finding, that currently fuel trims vary greatly even in warmed up range 180* to 210*. The flat spot drops to 8* come at warm as well. (Base min is set to 8)
    One thing that I also trying to figure out is if I have an actual issue outside of the tune because sometimes just going down the road power will drop off for some time. However, drops in timing seem to mostly coincide with that condition.

    My only previous tuning experience is on 411 ecu and ls motors
    Last edited by yevgenievich; 10-12-2022 at 12:43 PM.

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    This timing drop to 8* has been annoying and hard to trace down.
    timing8.jpg

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    No cats, no downstream O2s? But cat test & post O2 test still enabled? Desoot is also still enabled. Turn that junk off, especially the cat stuff especially if those parts are no longer being used.

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    Quote Originally Posted by blindsquirrel View Post
    No cats, no downstream O2s? But cat test & post O2 test still enabled? Desoot is also still enabled. Turn that junk off, especially the cat stuff especially if those parts are no longer being used.
    I was thinking desoot might be useful to keep, but after searching on it sounds like it should be off. I do still have cats, just no secondary o2. Will check on cat test. Thanks

  19. #19
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    Cat test looks for a response from the downstream O2s, so if they aren't there it can't get a result and keeps trying to run it.

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    Quote Originally Posted by blindsquirrel View Post
    Cat test looks for a response from the downstream O2s, so if they aren't there it can't get a result and keeps trying to run it.
    Interestingly, I do not have a cat test option under exhaust tab to change. Only lean/reach threshold setting for downstream sensors