DIY LTCC or similar system for LT1s

[spfautsch]

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.

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.

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.

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).

[kur4o]

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.

[spfautsch]

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.

[spfautsch]

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.

[spfautsch]

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!

[kur4o]

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.

[spfautsch]

I did one start with some idling till warmed up.

Are you meaning with engine running from all 8 cop coils, or some other testing configuration?

Started within 1 second of cranking.

This is not what I would call a good description of an LT-1 starting. I've had one somewhat "sketchy" start since moving to the 0.9.40 release. Otherwise it's been great, but with maybe 90 degrees more crank rotation. I actually logged it and can see the EST line arming / going high and then firing before the first cylinder would have fired (but wasn't because no dwell). I might do a pass-through thing for this to get fire sooner because the issue is going to be flooding the engine before any spark is delivered. But I think you have some other issues. A full second of cranking is very long for a healthy LT-1.

Will do more tests of random cranking.

My suggestion would be not to worry a bunch right now about trying to make it break during startup with random "trickery". Unless your perception of 1 second (1000 milliseconds) is a lot different than mine, you have some other start related issue that's obviously happening with your stock ignition system also. You said it here "Started on the second try which is not unusual on my setup".

I may be completely out to lunch here, but I think your injector flow constant is way off in left field. I would like to say you can trust me but I can't. What I can say is that after about a year of trying to extrapolate my IFC by way of trim numbers and then settling on where I'm at now, it hasn't started this well since I put my Multec injectors in the storage tote.

On light throttle change I feel very little hesitation, On hard throttle change no hesitation at all.

Let's revisit this after you answer my first question.