What is the 43 check engine code on a 87 camaro iroc?

There is no standardized OBD-II code "43" for a 1987 Camaro IROC-Z. OBD-II diagnostic trouble codes (DTCs) didn't become standardized until the 1996 model year. Your 1987 Camaro uses a much simpler diagnostic system, likely involving diagnostic lights and a process of checking components with a multimeter.

To find out what's wrong, you need to consult your vehicle's repair manual, or a Haynes or Chilton repair manual for that year and model. Those manuals will detail the diagnostic procedures for that specific car. The "check engine" light (if you have one) is likely an indicator of a broader problem, not a specific code.