INTERMITTENT IGNITION ISSUE

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Franko

Franko

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My 1969 Swinger 340 has an intermittent, one time miss/cutout which causes the car to jerk. It seemed like the ignition system cut out completely for a second. It always happened when I was cruising back roads, at about 2,000 RPM. This was nothing like a spark plug misfire. At first, this occurred once in a while.

When this first started happening, I had a Pertronix, Ignitor III and coil installed for years (the ballast resistor was bypassed).Thinking it was the Pertronix, I switched back to the dual points, condenser, ballast resistor, coil and spark plug wires.

These changes worked fine for months, but the intermittent issue returned. It got worse when immediately after the miss, the engine died but would start right back up. Just before I stored her for the winter, the engine missed and died, but then it took 3 or 4 tries to get it started again.

Is it possible that there is an intermittent short in the ammeter, ignition switch, bulk head connector (which looks fine), engine wiring, etc? I believe the ignition system is properly grounded, including the distributor hold down clamp.

It doesn’t seem to me that a bad alternator would behave in this manner or that it is fuel related. Since the problem only lasts a second, a multimeter wouldn’t seem to be useful.

Are there any words of wisdom to share out there? Thank you.
 
I would be looking at all of the grounds first, I believe.
 
All of the above. I would temp wire up a pilot lamp AND voltmeter to the common junction of the ignition "run" line in the engine bay. Get a diagram so you can follow it. The "run" line comes out of the bulkhead connector, and at some point branches to feed the ballast resistor, the VR, alternator field, electric choke if used, and on certain later models, a couple of smog doo dads. Monitor that and see what you find

You can also check it in your shop, "wiggle test" the bulkhead connector, the harness under the dash, and reach up and wiggle the ammeter connections.

The diagram on the ammeter article by MAD electrical is a good one to show you the simplified path.

The diagram below is VERY VERY important to understand the functional path of power all the way from battery to ignition. What is now shown here, is the last two or three terminal points, AKA the "run" wire feeding back out into the engine bay, through the bulkhead, and the splice/ terminals at the ballast resistor. ANY POINT where there is a connector/ terminal/ splice/ switch contact can be a problem, and there of course can be MORE than one


amp-ga18.jpg
 
Since it did it with both ignition systems it has to be something common to both. As mentioned grounds, and anywhere along the path from main splice to coil.

did you swap a known good coil in?
 
I hope so. Those Pertronix modules are pick about what coil to use.
 
EDIT: as to the missfire;

My guess is that one of the plugs has a cracked insulator.
Because this is sometimes very hard to see, I would change all the plugs. but I would also try to figure out how/why this happened, which is usually detonation or pre-ignition.
If I'm right, you gotta fix this. If the plug insulator breaks up and falls into the cylinder, there is no guarantee that it will go out the exhaust without doing damage.
 
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Years ago, I had a battery that was slightly loose in the battery tray. Sometimes when I made a left hand turn, the car would die and it would start right back up. I cleaned all of my ground connections but that didn’t solve it. After many weeks of frustration, I noticed an arcing site on the inner fender next to the positive battery cable. Seems that the battery would shift and the positive post would contact the fender and short the system. I turned the battery around in the proper orientation and made sure the hold down was very secure. That fixed the problem.
I’m not claiming that that is your problem but I do suggest that you check your positive cables and leads in addition to the ground connections.
 
Franko said:
Is it possible that there is an intermittent short in the ammeter, ignition switch, bulk head connector (which looks fine), engine wiring, etc? I believe the ignition system is properly grounded, including the distributor hold down clamp.
Click to expand...
Answers.
An ammeter short, like any short to ground, will take everything out. When the short is broken the battery will want charging. If this happens you'll see the recharging on the ammeter.
An ammeter connection that is loose will simply cause an open circuit. The engine will likely continue running.
Glance at the ammeter when the engine misses and it may tell you something.

Ignition switch or its connector. Yes - its possible either short or loose. Short is when power goes from the supply to ground bypassing the equipment it is supposed to run. A break or loose connection is an open circuit. The electrons go nowhere.

Bulkhead. Same as answer as with the Ignition Switch.

Engine wiring. Ignition Run circuit (J2) with blue wires. Same answer.

Franko said:
It doesn’t seem to me that a bad alternator would behave in this manner or that it is fuel related. Since the problem only lasts a second, a multimeter wouldn’t seem to be useful.
Click to expand...

A bad alternator will show up on the ammeter.
The needle will swing to discharge indicating the battery is suppying power when the engine is running. That's wrong. The alternator is supposed to supply power when the engine is running.
When the alternator is supplying power, the needle points straight up or shows battery charging (if needed).

I would not rule out fuel system, such as plugged idle passages if this only happens at low throttle. 2000 rpm, at steady 40 mph, could be relatively low throttle depending on gearing and tires.
 
Factory 1969 power scheme looks like this
upload_2019-9-27_12-47-7-png-png.png

I'd probably check inside the distributor cap for carbon tracks etc. Then the connections at the coil, then at the ballast, regulator and firewall. Might look at some spark plugs and the wires too if you think that ignition is a possible issue.
 
Sudden engine failure or misfire is nearly always electrical. A cracked spark plug insulator is not going to cause an 8 cyl engine to die, it will misfire.
I believe you have an open cct somewhere, not a short cct. The fact that the engine starts 'right back up' after stalling sounds more like a loose connection than a corroded connection.
Becomes a process of elimination. I would try a new coil &/or bal res.
 
I had very similar issue in our 67 cuda. When mine died twice it was on the 401 hwy(6 lanes) at 110kmh. NOT fun doing an immediate 4-5 lane change with no juice.
Anyway, check ignition switch. Our wiring was in great shape, BUT its 50+ years old and showing its age with cracks etc.
Good luck, I parked mine for 4 years and wanted to hurl dog turds at it.
 
Franko said:
My 1969 Swinger 340 has an intermittent, one time miss/cutout which causes the car to jerk. It seemed like the ignition system cut out completely for a second. It always happened when I was cruising back roads, at about 2,000 RPM. This was nothing like a spark plug misfire. At first, this occurred once in a while.

When this first started happening, I had a Pertronix, Ignitor III and coil installed for years (the ballast resistor was bypassed).Thinking it was the Pertronix, I switched back to the dual points, condenser, ballast resistor, coil and spark plug wires.

These changes worked fine for months, but the intermittent issue returned. It got worse when immediately after the miss, the engine died but would start right back up. Just before I stored her for the winter, the engine missed and died, but then it took 3 or 4 tries to get it started again.

Is it possible that there is an intermittent short in the ammeter, ignition switch, bulk head connector (which looks fine), engine wiring, etc? I believe the ignition system is properly grounded, including the distributor hold down clamp.

It doesn’t seem to me that a bad alternator would behave in this manner or that it is fuel related. Since the problem only lasts a second, a multimeter wouldn’t seem to be useful.

Are there any words of wisdom to share out there? Thank you.
Click to expand...
2 things that drive some crazy are the distributor connector loosing contact from heat cycling and plug wire cores burning out.
(Could be the coil wire in your case)

The distributor connector can be crimped a little tighter.
 
I hate to do this, but I’m going to throw some parts into this, in one fell swoop. I think the intermittent nature of this ignition issue calls for this approach, instead of utilizing the process of elimination. There doesn’t appear to be any way to take an educated guess to narrow down a possible solution, so I don’t break down and get towed home numerous times.

When this issue first began with the Pertronix Ignitor III in 2021, I replaced the mechanical voltage regulator with an electronic voltage regulator. What’s odd is that I also had to replace the voltage limiter when my gauges quit working shortly thereafter. I also noticed that my ground strap from the block to the firewall had broken off. After making these changes, the ignition issue went away for the rest of the summer, but returned and got worse in 2022.

I originally purchased the Pertronix coil with the Ignitor III. I also tested an MSD Blaster coil from another car. I don’t think it is the ballast resistor because I bypassed it for the Pertronix. I also installed the correct spark plug wires (72 and up) when I installed the Pertronix.

Are there any additional thoughts on what defective parts could cause a loose connection/open circuit for only a second, eventually causing the engine to die, followed by immediately being able to restart the engine? The ignition switch seems possible. What about a defective ammeter or bulkhead connections?

As far as a short circuit to ground for a second…could a defective alternator, bulkhead connections, starter relay, battery etc cause this to happen?

Are there any recommendations on where to buy the best quality ignition switch, bulkhead connectors and engine wiring.

A couple of years before these issues occurred, I hired Instrument Specialties to convert one of my ammeters to a voltmeter. But when I read the Mad Electric Ammeter Conversion Instructions, I thought all that rewiring was over my head, so I didn’t install the voltmeter. Last week I removed my gauge cluster and I am going to install that voltmeter and hopefully figure out the wiring. I also think I will change back to the Pertronix and see what happens.

Thanks for all the feedback.
 
I had an intermittent electrical issue (maybe many) that I chased down for a while. Each time I thought I fixed it (with lots of help from the forum) it would come back a few weeks/months later (really destroys your confidence in driving the car, too). Mine showed up mainly as no start situations, where the starter would turn but the engine would never start. Chased all kinds of things in the circuit over time (ballast, distributer voltages, etc.).

The last issue (maybe the same one the whole time?) turned out to be the ignition switch connections weren't making good contact. At one point while the car was idling in my garage I put in the parking brake and the whole thing shut off (interior lights and all) so that kind of clued me in. A few years ago I replaced the ignition switch and some of the new switch wires were longer than the stock switch wires, which made the connector hard to place out of the way of the brake, and I think the interaction of that connection with the parking brake, coupled with the old connections, caused the intermittent connection issues I was having. It might be worth wiggling that connection while your car is running to see if you can rule it out. I eventually replaced those connections with metri-pack connections (that was fun) since they were available and it has started ever since (fingers crossed...) I don't think you can get the original connections outside of a new wiring harness.

I'd aggressively try 67Dart273's wiggle test throughout the whole circuit before throwing parts at it. I've thrown parts at mine, too, but it gets frustrating when it doesn't work. If it is an intermittent electrical contact issue, any movement of the wire can cause it to make or break (bumpy road, replacing parts, wire wiggling etc.).
 
Update- When I started the Swinger up recently to change the oil, the 340 was missing, which was a steady fumbling for the first time, unlike the intermittent miss at 2,000 rpm. I switched back to the Pertronix Ignitor III and the engine ran fine (sitting in the pole barn). I also noticed that the points were burnt and the condensor bracket had a blue edge (pictures attached) where it may have been arcing. The screw was slightly loose and the condensor bracket could turn slightly, because the holes in the bracket didn’t match the nubs in the plate. So, it may not have been getting a proper ground at times. This might explain why the engine died, but started back up, but would not explain the 2,000 RPM intermittent miss that I had with both the Pertronix AND the points.

Then I started the Swinger to test my ammeter to volt meter conversion. But, the volt meter stayed buried for 45 minutes at a high idle. The charging voltage at the battery was over 15 volts, the whole time. I didn’t think that anything was wrong with the square back alternator (which didn’t have one of the two field terminals grounded), but I removed it anyway and took it to Autozone to get it tested. It turned out that it was producing 28 volts. The 69 electronic voltage regulator regulated the voltage at 15 volts. But, I think the excess voltage may have burned out the points even with the ballast resistor installed.

I think I read in a forum a while back that the 69 voltage regulator might not work properly with the 70s square back alternator, but it was confusing.

Could the bad alternator be the cause of the intermittent miss and burning the points out?

Autozone sells a remanufactured round back alternator rated at 60 amps and a square back rated at 78 amps. I was thinking of purchasing the round back 69 type alternator and stick with the 69 voltage regulator.

Are there any additional suggestions from the electrical gurus?

IMG_2446.PNG


IMG_2447.PNG


IMG_2461.PNG
 
You are on the wrong track with alternator testing, and I've preached this before: Test it YOURSELF ON THE CAR

The VR is what causes the alt to produce voltage. If the alternator is producing voltage--and too much--on it's own, then the green wire field terminal is grounded, or the field is internally shorted to ground

You have a 50-50 chance there. If the field is grounded, you may get the battery side (blue wire) on the GROUNDED side or the "safe" side, and THAT will be a blue smoke deal.
 
Get into the service manuals over at MyMopar. Estimate what the alternator is actually off of (late 72? 73?) and read THAT manual and read the part about testing for field current draw on the alternator.

It may be that you have an alternator with a heavy duty field, or partially shorted, that is taking out VR. You may have to look around and find a heavy duty 69/ earlier VR NAPA used to sell one that looks like the Mopar "race" one, and they used to have a heavy duty truck one. It is about square, about the same dimensions "square" as the "long" side of the 69 one is.
 
Run the car, monitor battery V and don't let it climb (use RPM) to keep it below 16 if it goes that high. Warm up the engine, the engine bay, and battery, and get it charged "normalized." Then, at idle, at fast idle, and at "medium cruise" RPM notate battery voltage. Should not be above 15. Turn on loads, headlights, heater, etc, and re-check.

You need to take a systematic approach.

These girls are SIMPLE compared to Fraud and Generous Motors with the old 4 pin idiot lamp VRs
 
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