PCM differences

[shrekmoose]

Been chasing my tail on some small idle problems in my truck and it finally occured to me. The original owner of the truck bought it new with a 4.3 tbi and blew a headgasket and swapped it for a 5.7 tbi. How do I tell if i have the right PCM in it. I would assume the spark and timing curves are different in the two motors maybe im missing out on some power and its causing my idle problem. Truck is a manual if that makes any difference.

 

[badazzbulldog]

check the service # on the pcm which is behind the glovebox any local junk yard can print the list of vehicles that the pcm works in

 

[Johnbalderas90k1500]

This may help
http://www.exatorq.com/ludis_obd1/p4xref.html

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