View single post by subwoofer
 Posted: 06-12-2019 03:43 pm
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Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 590
Finally got to the bottom of the misfire problem, it did reoccur but only after quite some time driving. It would idle just fine, then suddenly give up the ghost and die, just as if it was a fueling issue.

The solution was simple, again cheap, again ignition related. I won't get into details, but I suddenly saw my timing light go dark when it stumbled. Turns out the Pertronix Ignitor-II has an undervoltage lockout feature, so the ignition module was actually shutting down at idle as the module warmed up. Connected as per instructions (red wire to + on coil) the voltage drop through the ignition switch, tach, crummy old wiring, compounded by the hotter coil was enough that it would just go into shutdown when the rpms were low enough that the alternator wasn't really charging. One misfire or stumble could be all it took.

I really think I solved it this time.