Hi guys, I'm new here but I hope you can shed some light into my problem? I have a 84 CJ with a 4.2 straight 6 that has a Mopar Fuel injection for a 94 4.0. The problem is the engine starts pinging at about 2500 rpm under a load. What am I missing here? Is the wiring harness not correct or do I need to change the ECM? Please advise,,, I do appreciate any thoughts you may have to resolve this issue.