What is cpi

first post. reading the answers to my search.

what is cpi?

what is est - that needs to be disabled to do the timing?

1993 vortec 4.3

thank you

Central Port Injection, you can find info about it here:
http://www.automotiveforums.com/vbulletin/showthread.php?t=462726

thank you. not familiar with this motor setup. right now, just trying to find the basics of this motor before i start roubleshooting. i do not even know if this has the crank sensor.