Ignition problems ??

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Alf

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I am having problems with the ignition system on the '66 Dart. /6 auto

It started a couple of days back when the car refused to start. Motor turned over fine but would not fire. Checked all the wiring as much as I could and still no luck. left the car for a couple of hours and then it started fine.

I have started it several times over thee last couple of days. Then today I went to go out in it. Started it and it ran for about a minute and cut out.

Any ideas....... :banghead:
 
Very first question is what do you have for ignition system?

factory points?

Pertronix?

Mopar breakerless conversion?

other aftermarket conversion?

If this is points..........

make sure coil has power during crank

Make sure points are good shape and properly set

A bad condenser will cause loss of spark, and "new" does not mean "functional"

Coil could have failed.

Rotor cap dirty, wet, etc, carbon tracked

Bad coil wire.

What have you done to check for power or spark?
 
It has a Mopar electronic ignition. All the connections seem tight. Recently had cap, leads and plugs. When it runs it runs fine. Are the Mopar electronic ignitions known to be faulty?
 
NO, they are not known to be faulty, why would you think that? Ma made millions and millions of these starting optional in 71 or 2 I forget, and factory in 73.

Check power at the coil positive lead, both key on and "cranking" in start. In start, you should have "close to" battery voltage at coil+

Remove ECU, scrape firewall and mounting flange of ECU clean, and remount using star lock washers. ECU MUST be grounded

Remove connectors at ballast, at ECU, and distributor, inspect with a light for corrosion, and "work" in/ out several times to feel for tightness and to scrub connectors clean

Check reluctor / pickup gap at .008" (inches not metric) with a non-magnetic feeler. O'Really did have brass feelers

Inspect pickup and rotor for rust, debri, and strike damage. Crank engine and make sure distributor is actually turning

Remove distributor connector with key in "run." I forget which one, try them both. Grounding one terminal of distributor connector which leads to ECU should cause one spark every time you ground it.

Check the coil wire, or just check for spark. Get yourself a spark tester at any parts store. "Rig" it so you can see it through the hood gap, and twist the key to start.

Recheck by cranking the engine with the starter relay. Turn the key to "run" and use a screwdriver to jumper the two largest "bare" terminals on the starter relay.

These two tests provide different circuit paths for ignition power.

Check ballast resistor or just replace it. If you have a 4 terminal resistor, you have TWO resistors in that ceramic, the "long way."

If none of the above gets you anywhere, replace the coil, and then the ECU
 
Thanks for the reply. I will spend some time tomorrow checking things.
 
Also, since yours is a retro-fit, please post photos of your setup. Not that we can follow every wire, but to give an idea of the quality of the work. We have had people describe a pristine setup, then after much back & forth they finally post photos and we see corroded butt connectors, wires all over the place, exposed copper, rust, etc. Then the question becomes "how did you expect it to work?". Not fingering you, but show us what we are dealing with.
 
I wouldn't call this pristine work. The car has had all new ignition. Coil, Leads, Cap, ECU. All connectors seem to be clean and tight.

Problem is that trying to check things today and the car starts and runs perfect. Worst problem to diagnose is an intermittent one.







 
VERY FIRST THING I'd do is remove that ECU, scrape the mount clean, and get some star lock washers. If those are sheet metal screws, buy some bolts and nuts

It would not hurt a thing to add a no 10 ground wire from one mount bolt over to the engine.

Those ECUs MUST be grounded to operate.

Do the "wiggle test" on all connectors including your bulkhead connector. Pull it apart and inspect.

One very good example is the 2 terminal distributor connector. There's VERY little power going through there, almost none. This means that the slightest bit of corrosion in the terminals can "lose" the signal. Pull that connector apart. Hook it back up with only ONE terminal that is with the two halves "offset" Now twist the two back/ forth vigorously, hook up with the opposite two, and repeat.

For what you are doing, it really doesn't matter, either internal or external "star"

lockwashers.jpg
 
Thanks once again for the reply. I have removed the ecu and made sure it has a good earth. Also ran a separate earth wire as you suggested to the engine.

Those are bolts holding the ecu. I don't have any star washers until the shops open in the morning. Made sure it was bolted securely. Starts and runs perfect. Will take it for drive and see what happens.

Edit:....... Been driving all over town. Stopped and started the motor lots of times and it never misses a beat.
So, I don't know if it is fixed or not. Can only keep using it and see what happens.
 
Your wiring looks very competent. I agree w/ 67Dart273 that an erratic ground for the ECU was probably the problem (common). Still, I suggest carrying a spare ECU in the glove compartment. Many electrical problems are due to the factory relying on sheet metal screws to the body. Most newer cars use dedicated ground wires to solid ground studs around the vehicle, which has eliminated many problems. They learned.
 
The car has been running fine for a few days now. then yesterday morning I went to start it and it wouldn't start. It was popping and seemed like it wanted to just start on one or two cylinders. Then it started and ran fine. I am picking up a new ECU tomorrow and will see if that changes anything. I have another coil here I will fit but I really want to do one thing at a time so perhaps I will find the fault rather than just replace everything and not know what the problem was.

Frustrating.
 
Check your local parts store and see if they can test your ECU,

A few years ago my car quit and left me stranded, I immediately suspected the coil cause it didnt ohm out to spec. I took my ecu to the parts store and had them test it before I decided to buy a new one. It tested fine so I bought a coil and was back on the road.

Make sure whoever tests it tests several times to get the ecu good and hot, sometimes faulty untis test fine cold but not hot.
 
Thanks /6 Matt. I have a spare coil here I will try as well. Want to try another ECU first.
 
I do not understand..........if you have a good coil already, why on EARTH would you not try it first?

Some stuff I've found over the years, and I'm sure I'm leaving stuff out as it's "been"

Bad ground at ECU

Poor supply voltage. This can be ANYWHERE in the path from the bulkhead "feeding into" the car, the ammeter, the welded splice in the harness, the ignition switch connector, the switch, "back out" the bulkhead on the ignition feed, the connectors at the ballast, the ballast...........

and RIGHT IN the ECU connector itself. This includes corroded ECU terminals, looseness in the connector, and broken wires inside the molded rubber connector.



ESPECIALLY the distributor connector, as there's very very little current there, so it doesn't take much corrosion

Of course bad pickup

incorrect gap

sloppy distributor bushings, bent shaft, worn shaft

strike damage to reluctor wheel, or other debri, iron rust, etc, stuck to reluctor
 
Alf said:
Thanks /6 Matt. I have a spare coil here I will try as well. Want to try another ECU first.
Click to expand...
Um.... You misunderstood the moral of my story. Have the ECU tested before you go buy another. And make sure the test administrator tests several times to get the unit hot.

Electrical is black magic to me so my only other advice is listen to Del, 67dart273, he is an OUSTANDING troubleshooter.
 
Just looked at your photos...........is it my imagination or are the terminals on the ballast rusty?

Just one more thing, says Columbo.............LOL

columbo+scratching+head.jpg



Is your ECU getting WET? The heat sink and transistor on those is at HIGH VOLTAGE from the coil primary and can see hundreds of volts

"Back when" I had the Mopar in the B - T - S old FJ-40, I had trouble.. I'd get down in the mud or snow, and get water thrown up on the ECU, and it took me WEEKS to figure out WTF was causing a really bad miss..................
 
I have just replaced the coil. There is no difference in the running of the motor but then it was running good prior to that. It should however eliminate the coil from the problem. :banghead:

The problem only seems to occur during cold start.

Being in the middle of Xmas there is nowhere around here that I can get the ECU checked so I am going in the morning to borrow a known good unit from a good running car.
 
I have just replaced the coil. There is no difference in the running of the motor but then it was running good prior to that. It should however eliminate the coil from the problem. :banghead:

The problem only seems to occur during cold start.

Being in the middle of Xmas there is nowhere around here that I can get the ECU checked so I am going in the morning to borrow a known good unit from a good running car.

The ECU isn't getting wet.

The terminals on the ballast resistor are new and clean. The ballast resistor is new.
 
demoman3955 said:
shouldnt the ballast resistor be 4 prong?
Click to expand...

Don't know. That is how it was when I purchased the car.

Just went out to start the car (cold) and it started and ran perfect. Will pick up the replacement ECU later today.
 
demoman3955 said:
shouldnt the ballast resistor be 4 prong?
Click to expand...

Alf said:
Don't know. That is how it was when I purchased the car.

Just went out to start the car (cold) and it started and ran perfect. Will pick up the replacement ECU later today.
Click to expand...

Guessing from the looks of the ECU, no

There is no way to "for certain" tell by looking. That is, some of the 4 terminal, later, ECUs have 5 physical pins, but one is not hooked to anything.

Only way to tell is to "ohm out" the 5th pin and see if it's hooked to anything else.

So far as I know, only the older, Mopar factory ECUs are functional "5 terminal."

The difference:

Older 5 pin, requires 4 pin ballast

Ignition_System_5pin.jpg


Newer 4 pin, CAN use EITHER 2 or 4 pin ballast. Notice that the left resistor of the dual ballast is eliminated, going to the 5th pin on the ECU

Ignition_System_4pin.jpg
 
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