Did some test yesterday. I isolated (disconnected) the knock sensors and isolated the vacuum system to see what effect it would have. No beneficial improvement and live data timing is -25 degrees at 1050 rpm. Only thing that made a little improvement was cleaning out the chunk of carbon out of the EGR valve. I also hooked my Actron CP9145 scanner up to my 2000 Catera and it had showed +18 degrees advance (no minus in front) @ 1000 rpm. Scanner reads my vehicle as a 1995 Blazer so it's not seeing it as a 1996 or newer. I bought this scanner because of this forum that showed it was only one of a few that would read the 1995 PCM. I strongly believe that it is either the knock module or the whole computer that is the cause of this problem. Knock module ETA is Monday sometime. Let ya'll know what happens then.

 

Nice trip you did to the Alps then!
Yeah, makes for good rides. Have to go out on my motorbike one of these days.

As for your timing problem. Just another thought to eliminate a doubt. Already hooked up a timing light?

 

Well..........I haven't seen my timing light in over 20 years. I guess by now it is lost to the past. I'll have to borrow one and see what it looks like. Sure wish I'd read up on the 95 models as I would have only gotten one with the older ECM.

 

The 95's are an intermediate model year. They feature the new rounded body but the first built fell into the OBDI and it seems from the forums that GM produced several using up various equipment and making a mix of things. New intake and poppet style injection with differences to the final OBDII models.

If I'm not mistaken they should all have the OBDII connector thou and put data out in OBDII format. Maybe someone here in the forum can shed more light on that model.

 

I got that knock module on Friday and installed it. No real change in the way it runs and still shows minus for timing advance. Seems to run OK and I took it for an run down the road. I guess I'll never know if it is something with these early PCM's or not but my son can drive it and that is what I was wanting. Thank you all for your comments and advice. I'm going to check for that brown/black wire but it's too dang hot here in Texas so it will have to wait.