DIY LTCC or similar system for LT1s

[spfautsch]

All good info, thanks guys. I hadn't given much thought to the possibility of thermo-mechanical stress problems from hard potting. The catalyzed silicone sounds intriguing, but I may go with some combination of silicone around the soldered components and epoxy over that for impact resistance for mine.

I didn't see any mention of a tach driver in those diagrams, but at least the colors match what I have. For now I'm going to labor under the assumption that the 94-96 Y bodies have a digital gauge cluster. Edit 2: found an addendum to the ltcc install document stating that only a few LT1 cars had the tach driven off the coil - 92-94 y bodies and 93 f bodies. Sweet - sounds like I can eliminate that with conditional compilation for those who don't need it.

I'm sorry to report I haven't made much progress over the last few days but I did get about an hour on it yesterday during which the outside temp dropped from 62f to 32f finally settling in at a balmy 16f. It's back to "stupid" cold. :-\

After cleaning up some changes I hadn't debugged fully I was able to get a better picture of what the microcontroller is seeing. This looks likely to be a case of the EST line causing induced or capacitively coupled noise on the low res input. Edit: the test coil was disconnected at this point so the microcontroller was only driving leds.

R1000:S29:D27:C1:E0:L0
R1000:S29:D27:C4:E1:L0
R1000:S29:D27:C3:E1:L0
R1000:S29:D27:C6:E1:L0
R1000:S29:D27:C5:E1:L0
R1000:S29:D27:C7:E1:L0
R1400:S29:D37:C1:E29:L0 << looks like low res rising edge is caught about 29 degrees early here - eerily similar to spark advance
R600:S0:D16:C8:E59:L0 << low res falling edge is then delayed another 30 degrees
R1000:S29:D27:C4:E59:L16
R1000:S29:D27:C3:E0:L0

If I decide to brave the cold tonight I'll try some external pullup resistors on these inputs since the AVR's built-in pullups are advertised to be in the neighborhood of 20-40K ohms.

Another possible source of noise may be a ground loop - I added a power ground for the microcontroller to one of the fuel rail bolts but didn't disconnect the other ground at the opti pigtail connector. I'm open to suggestions on what the best practice is here - do I need some type of filter for this secondary signal ground or should I do away with it?