Chasing My Tail- Electrical Ignition Gremlin

[1973dodger]

I been chasing my tail concerning sporadic ignition issue, starting back in June my 73 Charger with a 440 would occasionally have a starting issue where it would start normally then immediately die. Started thinking it was a fuel issue, all checked out fine there. So started checking out the electrical side of the ignition, replaced the ignition switch and then ended up finding a wire going to the coil severely frayed, thought ah-ha found it. Repaired the wire, then went to start it, as the title of this post implies, it didn't fix the problem. So I did what any nonprofessional mechanic would do, started replacing parts starting with the ballast resistor, then decided to delete the stock electronic control unit and ballast resistor in lieu of an 4-pin HEI control module (wanted to clean up the firewall anyway) None of these fixed the problem, still starts and immediately died. After all that, replaced all the spark plugs, still no luck, but when finishing up with the number 8 plug, I found an 8" long tear in the insulation of the #8 plug wire.(Probably caused from exposure to heat from the headers) Yay, it started and ran, problem fixed, right? Well, the yes and no. Did fine for the next couple of cruise-ins, but last week started having the same sporadic problem with the next show I went to. It started up fine that morning, loaded it up on the trailer and got to the car show and the car would start, but not run again, so I left it on the trailer and went home. Once home, started doing a little research and saw something about an ignition time delay relay under the dash (not knowing at the time what it's actual function was), found it under the dash and unplugged it and shook it, no rattling, so reinstalled it. Car started up and ran fine, figured it was just blind luck, must have wiggled some wires somewhere under the dash. Since then, I found out all the time delay relay does is engages a small light at the ignition switch when the door is open and gets warm to the touch when engaged as long as the door is open. With that said, I know the following observance doesn't make any sense, but the aforementioned relay does more than get warm to the touch, it gets blistering hot and when it is that hot the car will start but will not run. When the relay is unplugged, the car will start but will not run. After the relay cools and is reinstalled, the car starts and runs fine. I know it doesn't make any sense, but after trying this multiple times since then, it appears to be narrowed down to this area. I have replaced the relay, but still same problem. Conclusion to this point is something is feeding this time delay relay hot all the time, even when door is closed, hence the reason why it gets so hot. Whether the following symptom applies, I do not know, but when the car is running and the headlights are on, the headlights flicker on and off. Obviously, I've got some wiring issues but any suggestions where to look would be appreciated.

 

[Geoff 2]

Is the vac adv hooked up? Every time the VA operates [ which will be often while driving the car ], the pick up wires inside the dist are being flexed. A point will be reached when they break....& you get no spark. It can be very intermittent & hard to find, & only expected with a high mileage engine. You can check the resistance, should be 150-500 ohms & flex the wires while checking.
Congrats on using HEI.

 

[1973dodger]

Is the vac adv hooked up? Every time the VA operates [ which will be often while driving the car ], the pick up wires inside the dist are being flexed. A point will be reached when they break....& you get no spark. It can be very intermittent & hard to find, & only expected with a high mileage engine. You can check the resistance, should be 150-500 ohms & flex the wires while checking.
Congrats on using HEI.

No vacuum advance, too much cam for vacuum advance

 

[Kern Dog]

No vacuum advance, too much cam for vacuum advance

I don't know how that could be true. When properly tuned, vacuum advance helps with fuel economy and burning more of the fuel that would otherwise pollute the oil or run out the exhaust pipe.
I have a pretty big cam but also have vacuum advance. 440/495 and 9.8 to 1 compression.

It is no surprise to you but intermittent problems are the hardest to diagnose, especially over a web forum miles and miles away. I've found that often times, electrical problems are the result of poor wire connections or loose grounds.
I've had some intermittent no spark issues that would show up without warning. For me, it could be a cold start or restart but the engine would just spin and not fire. Only once did I lose spark, stall and coast to the curb while the engine was running. That time, both the ballast resistor AND the ECM conked out at the same time.
A few months back when I was dealing with this problem, I took the bulkhead plugs off the firewall, cleaned all the spades with a wire brush and packed the open spaces with dielectric grease. I checked all the connections to make sure they were good and drove 1500 miles over a few months with zero issues. I went to a can show 400 miles away, (950 for the whole weekend there and back), I had numerous cold starts and restarts and it was fine....until both the ballast and ECM died at the same time. How common is that? I suspect that one took out the other but I can't prove it.
Ignition systems can really test your patience.

 

[Doorkicker]

Man... I truly hate electrical gremlins... so I feel for you. But I must admit... it's like an unsolved puzzle. LOL... my brain is like... m-u-s-t ....f-i-n-d.... i-s-s-u-e

Can you point me to the relay that you referred to in the pics?

 

[Doorkicker]

I don't know how that could be true. When properly tuned, vacuum advance helps with fuel economy and burning more of the fuel that would otherwise pollute the oil or run out the exhaust pipe.
I have a pretty big cam but also have vacuum advance. 440/495 and 9.8 to 1 compression.

View attachment 1728952

It is no surprise to you but intermittent problems are the hardest to diagnose, especially over a web forum miles and miles away. I've found that often times, electrical problems are the result of poor wire connections or loose grounds.
I've had some intermittent no spark issues that would show up without warning. For me, it could be a cold start or restart but the engine would just spin and not fire. Only once did I lose spark, stall and coast to the curb while the engine was running. That time, both the ballast resistor AND the ECM conked out at the same time.
A few months back when I was dealing with this problem, I took the bulkhead plugs off the firewall, cleaned all the spades with a wire brush and packed the open spaces with dielectric grease. I checked all the connections to make sure they were good and drove 1500 miles over a few months with zero issues. I went to a can show 400 miles away, (950 for the whole weekend there and back), I had numerous cold starts and restarts and it was fine....until both the ballast and ECM died at the same time. How common is that? I suspect that one took out the other but I can't prove it.
Ignition systems can really test your patience.

Hey @Kern Dog admittedly off topic... but quick question for you... seeing that our cams are not too far from one another... what is your initial and total timing? And do you mind sharing the curve.. such as when it starts and at what point it's maxed? Also, curious as to the vac adv degree you have set. thanks in advance (pun intended)

 

[WileE]

Ok, I didn't read all of the above. But, I'll just say this: First, clean/derust the bulkhead connector before going any further.

 

[bm02tj]

Replace pickup and recap with brass feeler gage

 

[Kern Dog]

Hey @Kern Dog admittedly off topic... but quick question for you... seeing that our cams are not too far from one another... what is your initial and total timing? And do you mind sharing the curve.. such as when it starts and at what point it's maxed? Also, curious as to the vac adv degree you have set. thanks in advance (pun intended)

I wrote all about it here:
What is your timing curve?

You could skip to the top of page 4 to get right to the point.

In short, I've narrowed the total amount of advance to allow me more initial and less total timing. I have it set around 19-20 at idle and around 34-35 total. I changed distributors and the rate of the curve a few months ago.

 

[1973dodger]

I don't know how that could be true. When properly tuned, vacuum advance helps with fuel economy and burning more of the fuel that would otherwise pollute the oil or run out the exhaust pipe.
I have a pretty big cam but also have vacuum advance. 440/495 and 9.8 to 1 compression.

View attachment 1728952

It is no surprise to you but intermittent problems are the hardest to diagnose, especially over a web forum miles and miles away. I've found that often times, electrical problems are the result of poor wire connections or loose grounds.
I've had some intermittent no spark issues that would show up without warning. For me, it could be a cold start or restart but the engine would just spin and not fire. Only once did I lose spark, stall and coast to the curb while the engine was running. That time, both the ballast resistor AND the ECM conked out at the same time.
A few months back when I was dealing with this problem, I took the bulkhead plugs off the firewall, cleaned all the spades with a wire brush and packed the open spaces with dielectric grease. I checked all the connections to make sure they were good and drove 1500 miles over a few months with zero issues. I went to a can show 400 miles away, (950 for the whole weekend there and back), I had numerous cold starts and restarts and it was fine....until both the ballast and ECM died at the same time. How common is that? I suspect that one took out the other but I can't prove it.
Ignition systems can really test your patience.

Thanks for the reply. Long story, but the jest of it is this engine is basically a race engine, mechanical advance only with a limiter plate in the distributor, hence the reason I trailer it to most shows (Pride for bragging rights is a terrible thing, LOL). When running works and sounds great, no missing or hesitation. My thoughts are; There are two power feeds coming from the ignition switch, one while cranking (which seems to working) and one for running (which seems to be intermittent at this time). For the life of me, found by accident only, why does this ignition time delay relay come into play regarding the problem? Each time it acts up with the running issue, I can unplug the relay, let it cool off for a few minutes, then reinstall it and wah-lah the car instantly starts and runs perfectly? This relay should not be inline with the function of starting and running.

 

[1973dodger]

Man... I truly hate electrical gremlins... so I feel for you. But I must admit... it's like an unsolved puzzle. LOL... my brain is like... m-u-s-t ....f-i-n-d.... i-s-s-u-e

Can you point me to the relay that you referred to in the pics?

View attachment 1728985

View attachment 1728986

I'll print the diagram off then let you know, but to describe the relay: It looks like a flasher but is 3 spade instead of 2, it is located behind the ashtray under the dash in the general location of the blinker flasher. It gets warm to the touch generally when door is open. However, mine is getting scalding hot and could pose a fire risk.