...How are your battery cables and ground connections?
This sounds like the typical Mopar ECU "Ground Loop" problem.
Basically the magnetic signal from the Dist is referencing the engine block ground, and the ECU is referencing the chassis ground (if the ECU case is even grounded good?
What happens is when the wiring gets hot, it creates higher resistance. Because voltage is Current * Resistance (V=I*R), the starter cranking current in the ground cable to the battery will have a voltage created. Because the Dist magnetic pickup is using a ground reference at the block, the signal at the ECU is at too high a voltage to sense the pickup signal.
Best fix is two parts, First good battery cables and ground connections, and second a ground strap from the engine block to the ECU box.
Hi gents, great forum you've got here.....this is my car. Thank you for all your posts. We've got some new things to look at.
^^^^451, I'm hoping you're onto something there. I get where you're coming from and a floating voltage wasn't something I'd considered. The battery cables were on my to do list down the track, they're pretty rooted. I'll clean up all the grounds, add a lead to the ECU and report back.
Lemme tell ya, the guy who finds the solution to this drama will be be in my good books forever! I don't
think this a pick-up problem. As mentioned earlier, we've installed a brand new MP dizzy and a brand new engine harness since this problem developed, and the issue has remained.
One thing that I picked up on when I last had a chance to lay hands on the car, the brand new dual ballast resistor I'd installed for reliability insurance had been manufactured a55 about! The .5 ohm resistor was in the 5 ohm spot, and vice versa. "The drama" started sometime after this resistor was installed.
Lesson there....these things are cheap for a reason, and measure twice, install once.
Cheers,
Mr G.
