Armchair QB's UNITE! -MOPAR Ignition - Fixed.

[JOES66FURY]

Okay, I will document this for the slim chance someone out there might make the same mistake.

First when converting from a points to a late model electronic ignition system in a vintage mopar you need the ballast resistor.

It is very important to determine which side of the ballast resistor is START and which side is RUN. It was not readily apparent to me when I did it nor was it today when I was shooting wires to determine the issue. My first clue that something was amiss should have stood out months back when I did this conversion. I noticed the coil was getting hot. It was getting really, bunt the crap out of your hand if you touched it hot. For some reason this did not raise any suspicions (we'll call that ignorance)

What I learned tonight is that you can wire this system backwards and it will still run. Take a look at the schematic and I will lay down my new found knowledge.


If you see the red and blue wires? you can swap their locations and the car will still start and run. However it will cause the coil to overheat because there is no voltage drop from the resistor. It is important to note that the wires from the ballast that lead to the voltage regulator is part of the RUN side.

Anyway, I rewired the whole system, tripple checked this diagram with the factory service manual and fired it up. I let it run, and it all seems to be what it should be.

I'll take it for a ride later and see if that hesitation I was having is gone...I suspect it will be.

[Beagle]

Glad to hear you got this worked out and didn't get hurt in the process! Having the coil blow in your face would have been what we old guys call "Bad."

Does it have a Holley? Wondering about the power valve...

[redneckjoe69]

so the ballast is kinda like a diode? sorta restricts current/voltage in one direction?
i suppose that explains the coil getting mega hot?


oh, do we get a pic of the exploded coil?

[TheSilverBuick]

AND THE COIL EXPLODED...


went inside to look something up, left the key in run position...came back out 10 minutes later and the coil blew the hell up...

As a general FYI for anyone, coils absolutely do not like power AND ground running to them with the engine off. Some systems will cut the voltage if the engine isn't running, others may not. One of the most common issues with EFI swapped cars are when the ignition system is wired up, folks hard wire the power to the ignition coils (any coil, single or distributorless) and leaving the key on, engine off, can easily cook a coil in a minute or so. I run a redundant shut off system in my cars, the coils only operate when the fuel pump operates (ecu shuts it off after 5 seconds when there is no tach signal), and I run a manual toggle switch to cut power to both the fuel pump and coils if I know I'm doing ECU programming/tuning work I'll manually kill the power supply.

Usually electronic single coil systems though, they cut the power if the engine isn't running though, well at least the HEI and external MSD boxes do. hmm.

[Beagle]

Good points Senor Burns.. I've heard of points being closed causing coil overheat issues way back when but I've never had that problem. Did they do something to accomodate that or was I just lucky? I always used the acc position for the radio anyway.

[TheSilverBuick]

Good points Senor Burns.. I've heard of points being closed causing coil overheat issues way back when but I've never had that problem. Did they do something to accomodate that or was I just lucky? I always used the acc position for the radio anyway.

Lucky.

[JOES66FURY]

Glad to hear you got this worked out and didn't get hurt in the process! Having the coil blow in your face would have been what we old guys call "Bad."

Does it have a Holley? Wondering about the power valve...

Yes, it does, power valve is in good shape no issues. I am on the fence about the size tho. It pulls about 10in at idle in D, and about 12 in P. I've been back ad forth between a 6.5 and a 5...not sure yet but I think it likes the 6.5 better but that goes against everything the Holley tuning guide says.

As a general FYI for anyone, coils absolutely do not like power AND ground running to them with the engine off. Some systems will cut the voltage if the engine isn't running, others may not. One of the most common issues with EFI swapped cars are when the ignition system is wired up, folks hard wire the power to the ignition coils (any coil, single or distributorless) and leaving the key on, engine off, can easily cook a coil in a minute or so. I run a redundant shut off system in my cars, the coils only operate when the fuel pump operates (ecu shuts it off after 5 seconds when there is no tach signal), and I run a manual toggle switch to cut power to both the fuel pump and coils if I know I'm doing ECU programming/tuning work I'll manually kill the power supply.

Usually electronic single coil systems though, they cut the power if the engine isn't running though, well at least the HEI and external MSD boxes do. hmm.

yes, good points indeed....that was my mistake. It did not help that it was wired to supply constant 12V all day everyday...Still learning at 40yrs old...damn shame that learning costs so damn much money.