New to me...94' LB4 "Z" (what PCM?)

I'm struggling to find the proper definitions, bins, etc for this S10 truck I bought.
4.3L V6 TBI, with E-Trans (4L60E), VIN designates as a "Z" (not a turbo like some lists indicate)
I'm thinking it could be the 427 PCM but don't know for sure.

It has 157K with a two yr old cat con on it, but runs really good.
Its failing emmissions for high (super high) NOx.
HC = 4.8 reading, 151.0 limit
CO = 0.0 reading, 1.68 limit
NO = 2788.9 reading, 956 limit (FAIL)

Ran it for an hour on highway and went back...
HC = 4.5
CO = 0.0
NO = 1822 reading (FAIL)

I'm figuring its the EGR solenoid since the valve opens and closes with vacuum applied.
I'd like to get in and turn on the solenoid to confirm the PCM is controlling it.

All info I find drops off the radar at 1993.
I know 94 is a bad transitional year so I could be in for a fun time.
Its OBD1 connector but gets nothing but jibberish using the $0D definitions so I'm wondering if there is a different one I should try.

Basically fishing for ideas..
Possible BCC and PCM numbers, ($E6 leftover?)
TIA,
Jp

Quote:

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Originally Posted by JP86SS

I'm struggling to find the proper definitions, bins, etc for this S10 truck I bought.
4.3L V6 TBI, with E-Trans (4L60E), VIN designates as a "Z" (not a turbo like some lists indicate)
I'm thinking it could be the 427 PCM but don't know for sure.

It has 157K with a two yr old cat con on it, but runs really good.
Its failing emmissions for high (super high) NOx.
HC = 4.8 reading, 151.0 limit
CO = 0.0 reading, 1.68 limit
NO = 2788.9 reading, 956 limit (FAIL)

Ran it for an hour on highway and went back...
HC = 4.5
CO = 0.0
NO = 1822 reading (FAIL)

I'm figuring its the EGR solenoid since the valve opens and closes with vacuum applied.
I'd like to get in and turn on the solenoid to confirm the PCM is controlling it.

All info I find drops off the radar at 1993.
I know 94 is a bad transitional year so I could be in for a fun time.
Its OBD1 connector but gets nothing but jibberish using the $0D definitions so I'm wondering if there is a different one I should try.

Basically fishing for ideas..
Possible BCC and PCM numbers, ($E6 leftover?)
TIA,
Jp

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Possibly a underhood flash based PCM??? Does it have a crank sensor and Vortec style crab distributor?

The one surefire way to find out is to take a look at the PCM and see what it says. Sorry, I can't help you with the smog problem, I stay away from vehicles that require it.

Yep, I wish I could stay away too!
I did find that it will log with $0D using my AutoProm.
My other cable must have issues.
O2 sensor does not change much at all when running. Doesn't go into CL for about 20 mins.

I did see something curious...
The O2 doesn't really change from around 0.500 mV but once EGR is engaged it immediately jumps up to around 0.900 mV.
Going to replace the O2 and see if the overall response improves.
Seemed odd that AFR was not bouncing but induction of exhaust caused reading of sensor to change quickly.
Don't know if that is a common failure mode for the sensor.

Still need to pull the panel and see what PCM/BIN I am working with.

All the 94 S-10 and Astro's I have pulled PCM's from have all been $0D.

UPDATE:
Cleaned out TB and New O2 sensor solved it!
Now onto the trans not starting in 1st when hot problem.
157 K miles and still runs good!