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#1
IP: 69.172.163.17
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Wasted Spark
Hi
Thought my pet project may be interesting to some of the people on this forum. About 3 months ago I started coding a wasted spark ECU mostly to improve my coding skills. I was quite happy with the code so I bought a cheap Bosch imitation coil pack and bench tested. Again I surprised myself when the thing passed all my bench tests. I plugged a really rudimentary development setup into the engine expecting a poor result. Again the thing ran better than I had hoped. So after some more refining my project now looks like this. https://youtu.be/STVazpihkaw The ECU has two cores, one runs the engine ignition, the other runs the wifi and a webpage to provide the data you see on the laptop. Any wifi capable device could display the data as the webpage is hosted in the ECU. Obviously the wiring is very quickly 'hacked' into place, the coil is held in place with a piece of scrap metal, the crank pickup is mounted using a piece of coat hanger but it gives you an idea of where I'm headed. Ultimately the coil will be mounted behind the head where the original coil is. My engine was running a distributor with electric ignition which ran very well. The new system runs at least as good using the 'ear' test. The spark is massive, the Atomic is so lowly strung compared to the vw group engines the coil was designed for I can run a huge dwell and the coil(s) never develop any heat. I can also start the engine at only 1 or 2 degress advance so it starts softly. There's also rev limiter. Thought I'd share. I've been enjoying building this thing. Last edited by cowlum; 11-28-2020 at 08:48 PM. |
#2
IP: 32.211.28.40
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OK, you've got me dazzled. Not sure what I'm seeing but the idea of an RPM limiter sounds great!
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#3
IP: 104.174.83.118
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If I'm seeing this right, you're discharging all 4 coil outputs simultaneously yet not getting combustion at the bottom of the intake stroke, correct? Or maybe I'm missing something. Have you taken the system out for a sea trial?
We've talked about a wasted spark system before with the goal of eliminating the distributor but a mechanical advance mechanism on the crankshaft made the exercise more daunting than it seemed to be worth. Our scheme traded the complexity of the distributor for the complexity of the crank mechanism and we were looking at a twin double output coil system (necessitating two crank pickups 180° apart), wasting only the exhaust stroke spark in each cylinder. We limited ourselves by sticking with mechanical designs, the result of old school concerns of electronics in a marine environment over the long term. Good on you for making a working prototype, I'm impressed.
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
The Following User Says Thank You to ndutton For This Useful Post: | ||
TimBSmith (11-29-2020) |
#4
IP: 100.36.65.17
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I'm guessing you used an ESP32 module for the MCU?
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@(^.^)@ Ed 1977 Pearson P-323 "Dolce Vita" with rebuilt Atomic-4 |
#5
IP: 69.172.163.17
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Thats exactly right! I've soldered a Wemos D1 Mini ESP32 to a pcb board of my own design. In future I'd like to surface mount just the esp32 to a board of surface mount components but I've little experience with that and will try it out when this one is in place and forgotten.
Originally I was using an ESP8266 but decided I'd like the ignition code to have its own core so the wifi has little chance of adversely effecting the running engine. Its only a few dollars more. Both MCUs have way more grunt that this project needs but horsepower is cheap. Last edited by cowlum; 11-29-2020 at 11:19 PM. |
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TimBSmith (12-01-2020) |
#6
IP: 138.207.177.95
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This is very cool
I have a project that has been on the backburner for a long time to make a dual coil ignition. I have the combiner that connected two coils one distributor, but still need the 2 ignition systems. I was going to use 2 Indigos with 2 sensors. |
#7
IP: 69.172.163.17
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Quote:
I did take it out for a run with my partner and 10 week old baby onboard, so I trust it. I can also run the engine at the dock which I do most of the time Im testing. The advance is in the code, I have a table that follows the rpm so the computer is advancing the engine as the rpms climb. If its still without issues at the end of this coming season I'll likely remove the distributor mechanism entirely. As it is now all I need to do to revert to the original setup is move the plug wires back, add power to the indigo electric ignitoin and she's good. Last edited by cowlum; 11-29-2020 at 11:17 PM. |
The Following User Says Thank You to cowlum For This Useful Post: | ||
TimBSmith (12-01-2020) |
#8
IP: 69.172.163.17
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Quote:
The rev limiter is quite basic at the moment it simply doesn't instruct the coil to fire if the RPM goes over a set RPM. I've chosen 2800 as its higher than the engine could possibly require in my Ericson 27. When it hits the rev-limiter the carb continues to flow gasoline which gets ignited in the exhaust so amusingly the Atomic pops like a supercar on launch control. In future I'll retard the timing before it approaches the rev limit and maybe let it fire every second cycle as it gets close to slow the engines climb before it gets there. But low priority at the moment. Last edited by cowlum; 11-29-2020 at 11:15 PM. |
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