DIY LTCC or similar system for LT1s

[spfautsch]

The flash based LT1 PCMs do, the older chip based LT1 ECMs do not.

Thanks, that's exactly what I was looking for! Shouldn't be an issue either way, there are plenty of open pins so I'm using the tach driver output to display the state of the EST input when in input test mode.

Just in case, I would check the alternator output for ac voltage ... Since the optispark runs off of 12V, I figure this could help.

I think I've got it sorted out, it wasn't a power problem. I just didn't know where the 12v power to the opti was connected to so I wanted to eliminate any doubt about adequate power. The extra signal ground from the opti pigtail also wasn't the apparent cause of the noise.

I ended up with 4.7k pullup resistors on the opti pins with a 1000pf cap on the low res input, and a 10k on the EST line. Oddly, 4.7k on the EST line set a "EST Open" code - 41 if memory serves.

I suggest running your coil trigger outputs through a buffer IC with 8 input/outputs. I think the proper term is "unity gain amplifiers", but they will probably be sold as buffers.

I'm opposed to growing part count unless absolutely necessary. When you test, if you can find a need for driving the coils w/ buffers we'll look into it.

The LS2 coils I have apparently have a very low current requirement on the igniter pin. I'm feeding mine through a 470 ohm resistor in series to the arduino pin. I'm also driving the sequencer leds from the arduino pins directly. I've noticed no issues thus far, but I'll save any further comment for when I've been able to bring the engine up to temp with the system.

Here's about a minute worth of video demonstrating cylinder #4 driven by the system with the opti running the other 7 cylinders. Once again, apologies for the shoddy camera work. I have no aspirations of becoming a videographer, amateur or otherwise.

Zip of logs here.