[sweetblue69]

I've got an ECU I'm going to use GM #16198262 and it has a custom chip in it for a 502ci crate engine. The harness it came with doesn't have the wires connected for a GM HEI/EST (computer controlled electronic spark timing with external coil) but I know the functionality is available for the entire series of ECU's but the custom chip maker (unknown) may have nulled the spark table(s) or it could be for a small block or other engine that doesn't require as much advance.

How do I test for spark advance functionality without using an eprom reader? Is there a good website out there specifically for GM EFI applications? I've only managed to find little bits and pieces.

[Steiner]

There's probably a wealth of info on thirdgen.com so I'd ask over there. Might be able to find someone who could look at it for you. Tunercat works with those old ECM's although I know nothing about it. They have free 30 day versions of their software on their website tunercat.com but you need the burner I reckon.