Start with a visual, inspect all vacuum lines for problems.
This is located on the top of the right firewall or under the battery. More than likely, it's under the battery. You must remove the battery and the bracket to see it.
Owners manual, positive.
knock sensor
knock sensor
System Normal
try your local libray dude .. they have lots of repair manuals for free
it is not adjustable, it is controlled by the computer.
any from 88 to 98
ESC / Electronic Spark Controll Circuit. and the knock sensor signal.
probably the ignition switch if you are refering to the starter solenoid.
41 to 47 psi
I have a 92 s10 blazer and my code 43 was fixed by replacing the knock sensor. so maybe check the knock sensor and the wiring from that to the ECM.