I'll post this question over here as well. I recently finished up a carb to TBI conversion on my 86 Chevy G20, donor parts from 92 GMC Yukon. Do I need to do anything with the trans park/neutral switch feed on the ECU? Also I don't have the crank signal wire hooked up, I'm guessing that's just a starting enrichment wire? I've noticed it can take a bit of cranking to fire up and am thinking that's the cause.

 

No 3rd gen was ever factory offered with a 350 TBI setup, only a 305 TBI setup. Not sure if there is a difference in the ECM concerning connections or not. But must not be too much of a difference, because we can take a 350TBI prom and insert into our 305TBI ECM's. Not sure if it helps, but here's wiring diags for the 305TBI setup anyway - scroll down and there's alot of 1992 stuff:

http://www.austinthirdgen.org/index.php?pid=19

I never knew there was any signal from NSS to ECM, not sure why there would be, as the NSS won't let the car start unless in park or neutral anyway.

And crank signal wire I've not heard of, but sounds like maybe the wire that primes the fuel pump so that the injectors have gas right before cranking (since injectors don't hold fuel in a bowl like a carb does). If it takes a few cranks or seconds to start, is the fuel pump priming? On a 3rd gen, if it's slow to crank like that, we assume the fuel pump relay is bad or not getting the priming signal from the ECM - the car will crank anyway because there is an additional fuel pump circuit that runs through the oil pressure sending unit - when it senses oil pressure it will turn on the fuel pump.

Not sure if any of that helped. Good luck!

 

Appreciate the help/info. Yeah I just stumbled upon this forum looking up tuning info, as I'll be burning a chip for this thing at some point. From the best I can tell, GM did a pretty good job of keeping their electronics pretty much the same across the different engine sizes for the same year.

The fuel pump primes ok on initial ignition power, so I know that's not determined by cranking signal, I was just thinking it might have a "choke" function, for lack of a better term, that sprayed more fuel on cranking.

on the NSS, in TunerPro currently with nothing connected to the feed, the ECU sees the vehicle as being in drive at all times. I don't know if this causes a problem or not? It starts just fine, so know at least that isn't effected. Ideally if my turbo 350 has an NSS output that I could find, then I could hook it up, but not sure if it's even necessary.