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Thread: DIY LTCC or similar system for LT1s

  1. #736
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    I think I measured the rotor width and it was something like 46* so it is a mechanical limitation. Not sure if there is software limitation too, it will be in the tpu if it have one. You can safely raise the limit and see what happens.

    Too much advance needs leaner mixture and very little load on the engine. It is also cam dependent because the one I have don`t like too much at sub 35kp, I also noticed that lt4 calibration also have lower values at these range.

    Start with slow increase like 1-2* at a time. I noticed sometimes 1 degree makes the difference.
    Zero throttle coast down must be matched with the main table so you don`t feel jerking when you left the throttle. It also greatly affects fuel economy.

    When you are finished the fueling might need revision too.

    I am still waiting on the caps and will be more than happy if we figure the coil sticking problem since then. At least I will not be much worried of coil`s ignitor melting.

    I will try to pick inductive signal from stock coil plug wire[coil to cap] with visual identification, so we can match it with the sticking coil, Or you can add some debug logging of est signal state.

  2. #737
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    You can safely raise the limit and see what happens.
    Planning to drive it Friday with it set at 58. Hopefully there's nothing in the TPU that will screw with me...

    Quote Originally Posted by kur4o View Post
    Too much advance needs leaner mixture and very little load on the engine. It is also cam dependent
    Mine has 50+ degrees of overlap, so it's like having the EGR valve stuck open below 2000 rpm. More EGR means less dense mixture that burns slower and wants more advance to hit peak cylinder pressure at 12-15 atdc. Judging from the sound difference at part throttle, it likes it.

    Quote Originally Posted by kur4o View Post
    Start with slow increase like 1-2* at a time. I noticed sometimes 1 degree makes the difference.
    I'd taken a few degrees out of the stock tables in most areas after the initial build with the cam and roller rockers. But I had ridiculous amounts of false knock until going to the shaft mount rockers so never worked further on timing. Now that I can (generally) trust the knock sensors I'm going to push a couple degrees at a time until I see something happen. I have all forged internals now so not too worried about a little real knock.

    I'm attaching the bin - the cells that are hitting 46-48* advance target are all below 45 kpa with the car in motion. It idles at 43-48 kpa, so these are all in the "hump" right before DFCO kicks in.

    Ideally I would get it on a dyno to find MBT, but I've yet to find anyone with a load cell setup.

    Quote Originally Posted by kur4o View Post
    Zero throttle coast down must be matched with the main table so you don`t feel jerking when you left the throttle.
    Thanks for the suggestion - I didn't even know there was such a table. This could explain my parking lot bucking issue. Would you know the address offhand?

    Quote Originally Posted by kur4o View Post
    ... will be more than happy if we figure the coil sticking problem since then. At least I will not be much worried of coil`s ignitor melting.
    I have a new board 70% built and plan to finish it this weekend to test this. But if it's only happening during initial cranking it's not a problem I'm going to lose sleep over.

    And you're not going to be melting anything. For the umpteenth time, the coils have built-in dwell limiting. You can dwell the m.f.ers 24x7 for days and not hurt them.

    Quote Originally Posted by kur4o View Post
    I will try to pick inductive signal from stock coil plug wire[coil to cap] with visual identification, so we can match it with the sticking coil, Or you can add some debug logging of est signal state.
    I wouldn't get too crazy worrying about the sticking coils, unless they're sticking after an additional full engine revolution.

    However, if you have access to an oscilloscope I'd love to know what (if any) time difference there is between the distributor coil firing, and the COP coil. A couple of inductive pickups on plug wires would handle this. You're not going to be able to see it with 60 fps video - it's going to be on the order of a few hundred microseconds or less (0.0001s being 100 microseconds).
    Attached Files Attached Files

  3. #738
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    Quote Originally Posted by spfautsch View Post
    Thanks for the suggestion - I didn't even know there was such a table. This could explain my parking lot bucking issue. Would you know the address offhand?
    Maybe this? http://fbodytech.com/tutorials/fix-l...e-stall-saver/

    Even on my stock car, it made stop-and-go traffic far less jerky. If it's not that, I'm not sure what it would be.
    1994 Corvette (Automatic)
    1995 Corvette (Manual)

  4. #739
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    Note:
    The tables & descriptions vary depending on whos XDF you use

    Steveo's XDF describes these as Stall saver.
    Kur4o's XDF describes these as Coast Spark & lists the tables differently to Steveo's

    Thanks
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  5. #740
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    I'm not bugging about it, but I did notice that also and that there are some tables that look to be specific for autos as well.

    Whatever the case, it's been disabled for several years.

  6. #741
    Fuel Injected! spfautsch's Avatar
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    Put some drive time in today tested more carefully with the 0x12045 Maximum Spark Advance set to 58 and still noticing some skipping. It's happening at the same RPM so I think it may be an issue with the controller that wasn't manifesting with lower spark advance numbers. I haven't yet ruled out the possibility it's the EST line not being "fired" by the PCM - hoping to isolate the problem on the drive home.

    kur4o I had some spare time over the past couple days to pick through your video and logging more carefully. I think we had a bit of misunderstanding - I was under the impression the crank attempt in the first video 'MOV02023.MP4' was included in your debug log 'log2.txt'. I also tried to match up your annotation and found it wasn't quite in sync with the numerous crank attempts, which lead me to believe there was some other problem happening in the 2nd one. So I went through it frame by frame to find timestamps and correlate the sequence and what happened with each attempt. The attached log has my timestamps in it, and everything seems to match up.

    Of all these sticking events, none appear to be caused by anything other than the controller dwelling coils before the PCM has started to control the EST line. In fact if you look at attempts 8 and 9 you can clearly see "stuck" coils from attempt 8 being fired in attempt 9 when the sequence comes back around to them. So I'm completely confident this isn't part of your no-run / incorrect sequencing issue. Preventing this should be simple and I'll try to do that this weekend, but it would only pose a problem with the D585 coils that fire when they reach dwell limiting.

    The only thing I'm seeing here that worries me at all is crank attempt 14 beginning at 2:28.24

    Code:
    strtDegs=57 strtLRCnt=2 strtSeqDeg=0 invSeq=0 firstCyl=7
    d cyl=7 dwlDgs=15 ectTbl=0 qIdx=1
    f cyl=7 saDgs=10
    c @ 89 dwlTgt=6 dwlDgs=16 qIdx=2
    d cyl=2 dwlDgs=16 ectTbl=0 qIdx=2
    f cyl=2 saDgs=9
    c @ 90 dwlTgt=7 dwlDgs=16 qIdx=3
    d cyl=1 dwlDgs=16 ectTbl=0 qIdx=3
    f cyl=1 saDgs=10
    c @ 89 dwlTgt=7 dwlDgs=17 qIdx=4
    d cyl=8 dwlDgs=17 ectTbl=0 qIdx=4
    f cyl=8 saDgs=10
    c @ 90 dwlTgt=8 dwlDgs=18 qIdx=5    << TDC semaphore, advance sequencer to #4
    f cyl=4 saDgs=10            << fire coil #4 but hadn't been dwelled
    c @ 90 dwlTgt=7 dwlDgs=17 qIdx=5    << TDC semaphore, advance sequencer to #3
    c @ 90 dwlTgt=76 dwlDgs=86 qIdx=5    << TDC semaphore, advance sequencer to #6
    d cyl=6 dwlDgs=86 ectTbl=0 qIdx=5
    f cyl=6 saDgs=19
    f cyl=6 saDgs=-1
    c @ 89 dwlTgt=2 dwlDgs=12 qIdx=1
    Watching and listening carefully even at 1/3 speed it's not completely clear if all this happened before or after the moment you released the key and disengaged the starter. It may have been the engine turning backwards slightly from the compression built up in cyl #4.

    Edit: Looking at the last TDC semaphore here this is almost certainly the engine turning backwards because the dwell calculation (what the 'c' stands for here) is wanting 86 degrees of dwell. That's a number more appropriate at > 2000 RPM, which you obviously weren't anywhere near.

    Whatever the case, you might want to re-verify that C2 on the low res input is the correct part - should be marked 102, not 104.

    If there's a noise issue on your low res line that could cause sequencing issues. You might try re-organizing your wire routing to make sure the inputs for the board are separate from the coil outputs. It could also have been related to the electrolytics being reversed.
    Attached Files Attached Files

  7. #742
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    Hopefully I will get the new caps tomorrow.

    Speaking of noise, The wideband I have is noisy as hell[the pwm heater]. I had to make some crazy emi filter for the radio interference.

    Do you know some way to monitor the status of est line other than a scope.

    The low res cap is checked and it is the correct one.

    I plan to wire all the coils with plugs and run it in parallel with running engine looking for noise.

    I looked at the video and couldn`t tell either what is the issue.

    I think it will be better to move the tuning conversation in the other thread, so the controller stuff don`t get polluted.

  8. #743
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    We could "attach" the EST line to the OUT1 led if you wanted. But that's only going to tell you what the board is seeing and we already know that from the logs. I think I'd be more concerned with sequence (i.e. the low res signal) and not worry as much about EST unless we absolutely can't figure your issue out. I still plan to try and check for the same sticking coils condition this weekend - I'm 99.9% confident it's not unique to your car.

    Running in parallel sounds like a good way to make sure the coils aren't creating a noise problem. But if I were you I'd still re-route the coil output wiring away from the EST / opti inputs.

    Whatever the case, when you get to a point you're ready to test again I'd really appreciate it if we could be slow and methodical about it. If you need to use the car for transportation this is going to take a while. I trust you understand things well enough to troubleshoot on your own, but the software side of this is something I haven't seen you express much interest in. If that's where you're going to stay, we really need to collaborate better on getting this working, because the software comprises most of the pieces of the puzzle, and we mortals do not have the resources the OEMs do to make stuff like this happen. I apologize for my lack of help last week - the timing made it tough. I'd taken my wife someplace nice for our anniversary, and she understandably got perturbed when I would run off to reply or look at your videos.

    It's not necessarily a tuning convo - I wanted to make sure the controller would work with spark advance greater than is possible with the distributor. About 10 minutes after clicking submit on the last post I found the problem in the firmware. I'd used the MAX_SPK_ADV constant in the controller firmware to build the queue grow / shrink thresholds, when I meant to (translation: should have) used the ENGINE_GEOMETRY constant. D'oh! Fixed the hard skip issue, which didn't exist until I increased the MAX_SPK_ADV constant.

    Got a good log on the drive home with no missing whatsoever. I'm definitely a bit "hot" on timing in a few areas now, but not everywhere - certainly not the load cells where it's commanding 46 degrees. I actually heard audible ping once on the drive home, and that's never happened since I've started tuning for the cam. That's the end of my "tuning" discussion for this post.

    Besides, this thread has gone so far off topic it's almost comical so what's the harm in a few hundred more words? When it officially becomes a project instead of just the ramblings of a redneck with too much time on his hands, I'll create a more official place for discussion.

  9. #744
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    Caps arrived and are installed.

    Hope to test soon.

    I already did a quick tune up of the engine. Adjust lifter preload + checked all spark plugs and readjust gap to 1.25mm, due to self widened to 1.4mm.
    The plugs look great and clean, due to the mixture being almost perfect now. Also measured the headers temp with quality laser gun. at around 2 inch from flange 1-2 and 3-4 measured around 240-250*C, 5-6 and 7-8 around 220-230. Interesting very close to the flange the temp were around 190-200*C.
    This is done with almost perfect blms at around 128 and no split at all after good 10 minutes of idle to stabilize temp on fully warmed engine.

    The temp difference is normal due to less fuel being burned and less heat produced accordingly.

    If you are having problems with some colder running cylinder and split blms the trims will need adjusting.

    I am looking for suggestion as where to start with controller testing.

    I am looking more of a external type of est monitoring. I have some home made 1 channel hobby kit scope that can be hooked to the est signal.


    You need to look at the stall saver tables and scalars defined in the Steveo xdfs. They are used only on manual cars, and adjust spark advance with low tps mph situations and prevent stalling. If you have zeroed them, load a stock y-body manual bin and look for stock settings.

    You can also revisit the closed tps advance table at the high rpm, and match them with the low map advance table.

  10. #745
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    Quote Originally Posted by kur4o View Post
    1-2 and 3-4 measured around 240-250*C, 5-6 and 7-8 around 220-230. Interesting very close to the flange the temp were around 190-200*C.
    That's not much out of range of what I see. Generally 280*C on the front cylinders and 50-100*C less on 7 & 8. But with the y-body hood design temperatures go way down with more idle time and having cooling fans running with the hood open. I've spent hours idling it in the garage both nose-in and nose-out, closing hood in between measuring and not closing hood. Measuring for 10-15 seconds per tube. It's just all over the place, especially when in closed loop with the integrators oscillating.

    You make it sound easy. I would gladly buy you a round trip plane ticket just to see the look on your face afterwards. As good as I've ever gotten it, all it takes is a strong weather change or simply turning the A/C on to throw it all out the window.

    Quote Originally Posted by kur4o View Post
    I am looking for suggestion as where to start with controller testing.
    My personal plan of attack would be:

    0) Sorry to be a broken record but re-route the coil outputs away from the inputs if you haven't already. My suggestion is use temporary loom (i.e. the spiral wound stuff or just some electrical tape) on your wire bundles so they stay neat and separated. This will help prevent induced noise where an output wire may be in close proximity to an input wire (i.e. two wires laying directly against each other for several inches can create a pretty efficient coreless transformer in certain conditions).

    1) Try running controller in parallel w/ stock ignition, firing all 8 coils to verify no issues driving all simultaneously. Make sure to have some dummy load / grounded plugs on them or you'll have an EMI circus going on under the hood. After engine comes up to temp restart and re-observe.

    NOTE: Don't try jogging the starter trying to make coils "stick". Crank it to start and let it start. Then observe coil leds when running.

    2) If step 1 successful try running with one LS coil driving a cylinder of your choice. Start engine and then disable that injector via eehack to confirm it's firing w/ correct sequence (i.e. if no RPM drop, it wasn't in sequence). At colder engine temps the RPM drop will be more pronounced. Do this both cold and at temperature. Test a start at temperature, repeating cylinder disable test. Considering your observation of kickback previously, you may want to repeat this test several times cold and hot, over several days. Again, if you're depending on the car for daily transportation, take as long as you need. I'd rather we fail miserably at this endeavor than have you fold a connecting rod.

    3) If step 3 successful either gradually transition to all LS coils or go all at once, at your discretion. Use a cylinder balance test to verify all are hitting. If you have any difficulty starting that's not typical w/ distributor ignition stop and report back.

    If at any point you have coil leds sticking after the engine is running stop and report back. Take logs of everything and be methodical with keeping track of what's what. If you have any issues I might give you some things to log periodically that could tell us more.

    Quote Originally Posted by kur4o View Post
    I am looking more of a external type of est monitoring. I have some home made 1 channel hobby kit scope that can be hooked to the est signal.
    1 channel won't give you much to work with because you'll have no frame of reference. The uart data sent from the controller can be delayed by higher-priority interrupt handling, so it's not going to be close enough to real-time to be useful against a scope display. My suggestion would be to follow the above testing steps slowly and carefully. If I see anything that makes me believe there's a noise issue with the EST line I might be able to write some debugging hooks to help us troubleshoot. Today's been a wash so far so I haven't been able to make progress on my setup but I have very little reason to believe I won't be able to reproduce your sticking coils test. I just dread the thought of putting my starter through such torture.

    Quote Originally Posted by kur4o View Post
    You need to look at the stall saver tables and scalars defined in the Steveo xdfs. They are used only on manual cars, and adjust spark advance with low tps mph situations and prevent stalling. If you have zeroed them, load a stock y-body manual bin and look for stock settings.
    Thanks for the suggestions, I'll take a look once I have the main timing tables where I like them. I was able to confirm smooth engine function at 47 and 48 degrees advance, so my main question has been answered. I have no doubt 50-52 degrees is possible (though probably not needed).

  11. #746
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    Not much testing done, but here are some pic update.

    The spark plugs gurus can chime in with some suggestions. #1 and #2 are a little whitish with slight green tint. Other are a little darker.

    I am sure you can dial the blms with more advance methods. Like making some remote live tuning session over the web.

    The last attempts I did dialing were using the blm split method and a little of the eoit target.

    I also finally got rid of the warmup leaning at some temp range around 45-60*C. Playing at EOIT target during warm up, at both directions, I copy the vette settings going straight from $40 to $60 at 44*C. That seems to cure it now.

    Now I got some other strange issue. At 60-65*C I got blms at around 132, from 65-70 they hover to 123-5 and after that they slowly recover again to 128. I still have no clue is it EOIT, advance or MAF curve.
    Attached Images Attached Images

  12. #747
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    I was able to reproduce the sticking issue and think there's a slight possibility it's leaving the sequencer in an odd state. Will need to do more testing.

    First fire with new board was as perfect as it could be. Completely untested it powered on, new firmware flashed, key off, disconnected uart and it started and ran immediately.

    Then I setup some cameras and pulled the injector fuses to try and reproduce the issue. Only took a couple attempts. Once I had a coil stuck on I replaced the fuses, and was surprised to find no signs of fire whatsoever even though the controller was appearing to function correctly. Three or four attempts and still nothing. Key off and back on and started immediately albeit somewhat slobbery and rough initially.

    Unless the PCM employs some kind zero TPS flood clear routine that resets with key off, I'm not sure what's happening here because I was sitting in the passenger's seat. I'm almost certain I cranked it long enough at least once or twice to set the run flag, which should have switched to MAF fueling and allowed it to start. I'm going to try from the driver's seat and pedal it a little - it's possible it was absolutely devoid of fuel and needed a fresh prime pulse.

    Will test more thoroughly this morning and report back.

  13. #748
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    Wasn't able to get it to restart by giving it some pedal but ether worked. I suspect it would have stayed running had I given it a fatter shot of ether, but I'm not crazy about using it in my mostly closed, attached garage.

    I attempted to start initially with both injector fuses pulled, then once coils stuck I put the fuses in, gave it a small hit of ether in the valve cover breather inlet on the TB, then restarted. It dies immediately but then restarts without removing power to the controller. The video is only one attempt but I was able to repeat this sequence three times in succession so it's not a fluke.

    The first link is lower quality 5.3MB the second is 44.3MB at original resolution of the same attempt.

    Low Q

    High Q

    I'm not considering this definitive proof something else isn't going on when these stick, but I see no reason an ignition system deficiency would cause it to start and then die on ether. And I'm otherwise extremely happy with general starting reliability - since adjusting my injector constant to what I feel is a more realistic number, starts have been spot on at all temperatures and conditions I've been able to test.

    At any rate I'm going to seal up the wiring going through the acrylic so I can put it together and drive it. I should have a revision ready later tonight or tomorrow that will address the coil sticking during initial cranking.

  14. #749
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    Here's a fix release that addresses the coils being dwelled before the PCM has demonstrated control of the EST line.

    I tested the issue in question and was unable to reproduce it at initial cranking with this firmware. I have a couple videos if anyone would like to see them. There may be the possibility of instances where a coil sticks at the end of a cranking attempt, but I've no intention of addressing that for what I believe to be very good reason. Also, initial startup will generally be delayed by another 90* of crank rotation from the last release due to waiting for the PCM to "light the fire" so to speak.

    I didn't intend for this to be a major code revision, but when I started looking at how the high resolution and EST interrupts were handled it occurred to me they were being abstracted through the arduino namespace into somewhat less efficient constructors. This was eliminated. I'm going to call this an "interim" release because I removed a handful of references to pinMode() in this revision, and references to digitalRead() and digitalWrite() in the upcoming 0.9.41 revision. As near as I can tell, all that remains to make this compile within the Atmel AVR Studio is a suitable replacement for the arduino Serial object. But I'm not at all convinced there's good reason to do that. Anyway, the newer external interrupt handlers should honor the interrupt handling priority intended (EST being highest, then Hi Res input, followed by Lo Res input, then all others) when I originally conceived it.

    What this revision does is basically hook the EST interrupt to a rising edge trigger at startup as well as after a stall / no-start condition occurs. As soon as a rising edge signal is caught and confirmed it switches the interrupt to using a falling edge trigger in order to catch the coil firing event. The "protection mechanism" is that whenever the interrupt 0 trigger signal is set to rising edge, no coils will be dwelled.

    I've given this brief road testing. Will try to do more complete testing tomorrow - a clutch stall hot restart and a few other odbball cases. If anyone has more ideas for a testing "protocol" please post them!

  15. #750
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    Did some test with new firmware and all seems good. I did one start with some idling till warmed up. Started within 1 second of cranking. Will do more tests of random cranking. On light throttle change I feel very little hesitation, On hard throttle change no hesitation at all.

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