Need some help from you smart guys. 1990 XJS V12. Blew an A bank coil recently, small fire, burned up the harness connector to the coil and the coil itself. Two huge backfires as it was loosing power running on only B bank. Managed to drive it onto and off a car trailer to get it back to our shop. Replaced both coils, new connector spliced in, new cap and rotor (didn’t need them but did it anyway, and yes, rotor mod done per The Book two years ago and now). Also installed new plugs. plug wires and coil wires look good, new two years ago. Well, after installing the new coils and other stuff mentioned, it wont start at all, not even on the B bank that it ran on before. We did verify fuel and spark working.
So, in we went; wrung out all of the ignition harness. Point to point continuity all the way to the computer in the footwell. Checked coil wiring, checked crank/speed sensor wiring including the problematic little solder connection on the crank sensor, checked ignition amp wiring, all good. Still no start just mild backfiring as if it were out of timing. rechecked all plug wires to validate we landed them correctly at the dizzy. Then did a psuedo timing check by lining up the rotor with A1 at TDC, all good. We then replaced both the crank and speed sensors, still no start. Found a used computer which was claimed to be good. Installed that, still no start. None of those things changed anything, still just mildly backfires like a timing issue. The only ignition parts we didn’t change were the ignition amps up front on the radiator support. They are stupid expensive and as you all may see from what I have replaced I have spent a ton already. Any thoughts or suggestions? I’m at the very end of my ideas right now!!