DIY LTCC or similar system for LT1s

[vilefly]

I have to agree to low parts count. Nice video. Got a question. Is your LS1 ignition coil hooked up the the same + lead that feeds the ignition coil? I know the ignition coil feed has a noise capacitor on it right at the coil. Other manufacturers do this too. Try using the V+ feed for the OEM ignition coil and see if your noise goes away. The inductance of he other coil may dampen some noise as well. The ignition module may have other noise-dampening circuits in it (on the shared positive side), such as a zener diode or something. No extra parts required.

[spfautsch]

Is your LS1 ignition coil hooked up the the same + lead that feeds the ignition coil? I know the ignition coil feed has a noise capacitor on it right at the coil.

Yes, and I'm relatively sure there's nothing like that on my '95. Last weekend I stripped the tape off the entire right side harness from the #8 injector to where the MAF sensor branches out including all of the ignition feeds and there's nothing but wires and connectors.

If I can find all my old spark plug wires I'll try firing it with the original ignition system disconnected tonight. Fingers crossed, bunghole clenched...

[spfautsch]

As my videography skills run, I accidentally deleted the crank / start segment from my phone. It was unimpressive because I'd already started it twice before - once so I wouldn't drop my phone in the event the engine came apart and I soiled myself, and the second time my wife was "helping" with the video. The valves had warmed up by #3 so it was a bit of a long crank as I suspect it flooded slightly. After the final video when ECT was around 60c I re-started it and it fired off just as vigorously as we're all used to.

At any rate, proof of concept at long last. Also, revel in my woodworking skillz (temporary coil brackets).

Short clip revving (haven't looked at the logs to see peak rpm).

90 second clip showing eehack when it switched to closed loop. At the end I walk around and pick up the disconnected ICM and coil connectors as well as the opti coil wire.

Logs


After disconnecting the ICM plug, DTC 41 set immediately as it did when I was using a 4.7k pullup. So I suppose I might need to try a zener diode or something on this pin to keep the ECM from freaking out.

I'm stoked to have gotten this far. There's still a lot of work, but that's all going to be dead nuts fun for me.

What still remains to be seen is what the Atmega will behave like the first time I get stuck in St. Louis traffic on a 95F day.

I'm going wander over to my neighbor's place, have a couple glasses of bourbon and come home and sleep like I haven't in a few months. I'll do some research tomorrow and try to decide how to publish the source code.

[vilefly]

Very awesome work! I commend you on beating me to the punch very soundly. I especially like the wooden coil bracket, seeing how most bracket kits cost $85 and up.
You are using the mega2560 unit, right? I imagine you can send a password-locked zip file. If legality issues concern you, you can draw up a patent-style Disclosure Document that proves you thought of the idea before you disclosed it to someone else, and have them sign it, and send it back to you. This will hold up in a court of law, but am not sure if you need to have it notarized. Should provide you with some code protection at least.

What I don't know, is how you can download what has been flashed to the AtMega so you can prove the code was stolen with a comparison. Should probably keep that secret to yourself, though. Just say if you can do it or not.

As to the code 41- I think the circuit impedence on the EST line is 10k ohms. Perhaps a 10k resistor in between the arduino and the EST white wire might fix it. (ignition module terminal "B")
95 corvette optispark.png

[spfautsch]

Very awesome work!

Thx!

I commend you on beating me to the punch very soundly.

I wasn't exactly trying to scoop you - just possibly a little more enthusiastic about the prospect of <the title of the thread>. DIY is ingrained in me fairly deeply.

You are using the mega2560 unit, right?

No, 328P. 28 pin dip package. Google "DC Boarduino Kit". Us hillbillies with shaky soldering hands love 'em. I'll have to read the 2560 datasheet to see what changes would be needed to make my sketch compatible (if possible).

I imagine you can send a password-locked zip file. If legality issues concern you, you can draw up a patent-style Disclosure Document ...

My legal concerns aren't focused on you or the gearhead community at large, but the inventor of the namesake device. I just want to protect myself from legal repercussions if Bailey owns a patent and decides to go after me. The only reason I put all this work in is to have the source open and available for everyone to modify and improve upon.

What I don't know, is how you can download what has been flashed to the AtMega...

The compiled binary can be flashed with avrdude if you can wrangle the command line. But I don't intend to make it that difficult.

As to the code 41- I think the circuit impedence on the EST line is 10k ohms. Perhaps a 10k resistor in between the arduino and the EST white wire might fix it. (ignition module terminal "B")

I'm relatively sure the "EST Open" refers to not having enough loading on the EST circuit (i.e. the absence of the ignition control module). So adding resistance is probably going in the wrong direction. In the grand scheme of things this is the proverbial gnat on an elephant's ass.

[vilefly]

I just hope that the code 41 doesn't make the ecm lock the ignition timing.

I have 2 more spare arduino 328P pro mini's at my disposal. I bought 5 for halloween animated eyes that I made so I could teach myself about these things. So no need to recompile.

I need to get a hold of 8 ls1 coils still.

[spfautsch]

It doesn't seem to have any effect on timing, it's just an ECM diagnostic to let ppl know their EST wire is broken / disconnected. It would be simple enough to just disable the test in the calibration (if possible) but I'm trying to work around it electrically.

I've found that a 470 ohm resistor is enough load on this pin to prevent the code, at least while cranking. Unfortunately it pulls the voltage down enough the arduino isn't seeing the pin go high. So it might require a schmitt trigger or ???

I got a bit sidetracked trying to fix this issue and got off the task of posting the sketch. Will try to get it on github in a bit.