I have a 91’ integra eith a B16 and the ecu is a PR4 ecu, is this switching my vtec on and can I hook up a pr3 ecu with out mods> thanks for any help.
PR4 is the non vtec ecu, you need a PR3 or PW0 I believe. Check the engine swap guide in the trg tips, you will have to add 4 wires to activate the vtec with the new ECU.