if i put 2004 heads on a 2002 2.7 do i need to change the pcm

 

I had to change the cam reluctor when I went to 05-08 heads. I've never stayed within the 01-04 heads. I've never had to change the PCM. Not sure this is exactly the question you asked. I actually changed out the entire engine to a 05-08 to pick up the changes in the heads, water pump and cam chain tensioner.