Hi Steve and everyone else. The simplest way is to see if the data from the Ecm comes out at pin M on the aldl connector. Most of the 86 up Tpi,mfi cars had a P4 excepting fieros. CU:peter >On a related note, is there a simple way to tell by looking at the >ECM if it is a C3 or P4? I know vettes had the P4 ECMs, what other >models/engines did? > >--steve >