No Spark

[brodphish]

Regulars on this forum may recall a week or so ago I posted about suspected fueling problems as the 417 stroker I have was idling poorly. Well after a few day of back and forth here the car idled and ran great. Well after taking a neighbor couple for a super fun ride Sunday it would not start. Upon checking the carb was definitely getting fuel pumped into the primary barrels so I checked the ignition - no spark at all. I removed the coil and noticed oil leaking from it. On the way to work took it to an auto part store they - told me it was good. I suspected not. On the way home I upgraded my multi-tester and the old coil was out of spec. Replaced the MSD PN 8202 coil with a coil for a stock 340 (all they had). Still no spark (as confirmed with my new spark plug tester in place of my old school grounding method).

Checked the distributor, it looked good except the rotor had white dust all over it, which I cleaned with no effect. Any ideas on what to do next? We were hoping to take the car to a local show tomorrow but I guess not.

One final clue - when the car was idling poorly it also had a very slight surge at constant throttle, +- 50(?) RPM.

Any ideas?

 

[T56MaxTorq]

Coil was installed correctly? With the key on (and start) you should have 12v to the + side of the coil. Have you verified the reluctor to rotor gap? After that I would slave in a different ignition module.

The surge I would suspect to be a dead cylinder or misfire, likely from the bad coil. I've been stranded with a bad msd coil before, and it leaked oil too. Had to wrap it with water soaked rags to keep the heat down or it would just die, finally got home hours later, after changing the coil.

 

[brodphish]

I have to display my ignorance - what can go wrong with a coil installation? Two leads and a plug, correct? If there's more to it than that I may not have done it correctly. How to measure 12v at + ? It did sound like it wanted to fire for about 1 second after the new coil.

How do I measure the reluctor to rotor gap? I was already thinking new ignition module.

Thanks for the education - I need it.

 

[Johnny Mac]

I'd think that changing the coil with a new unit, and it ALSO being bad is a long shot. Id point more toward the mag pickup in the dist. I chased one of those all over the place for an entire summer. What kind of box and distributor are in it? Stock? Or msd also?

 

[dano]

What comprises your ignition system?

 

[AJ/FormS]

The reluctor gap is set with a non-magnetic feeler gauge around .011". Brass is the usual feeler material.The ECU will read pretty much any gap from zero to somewhere around .030gap.
What amp are you running? Factory types have to be grounded.I have heard that the newer Orange boxes crap out with no warning.For testing purposes,the factory systems will run with any factory amp. Just swap anything in there; anything.
And as always, the no1 most common failure point is the ballast resistor.
The least likely to fail is the dizzy or anything in it.
The no2 most likely failure point is the bulkhead connector.

 

[Rustedwrench]

Regulars on this forum may recall a week or so ago I posted about suspected fueling problems as the 417 stroker I have was idling poorly. Well after a few day of back and forth here the car idled and ran great. Well after taking a neighbor couple for a super fun ride Sunday it would not start. Upon checking the carb was definitely getting fuel pumped into the primary barrels so I checked the ignition - no spark at all. I removed the coil and noticed oil leaking from it. On the way to work took it to an auto part store they - told me it was good. I suspected not. On the way home I upgraded my multi-tester and the old coil was out of spec. Replaced the MSD PN 8202 coil with a coil for a stock 340 (all they had). Still no spark (as confirmed with my new spark plug tester in place of my old school grounding method).

Checked the distributor, it looked good except the rotor had white dust all over it, which I cleaned with no effect. Any ideas on what to do next? We were hoping to take the car to a local show tomorrow but I guess not.

One final clue - when the car was idling poorly it also had a very slight surge at constant throttle, +- 50(?) RPM.

Any ideas?

I got an idea. If people would take the time to learn some basic electrical theory and purchase a shop manual instead of the latest hyped-up go-fast parts, they could diagnose something like this in about 2 minutes. Understand, I am not picking on you specifically. You are not the first to have a high-dollar engine that won't run.

An ignition coil is a simple step-up transformer. That is it. A transformer works according to the principle that electrical current moving through a wire produces a magnetic field around that wire. As it happens, the reverse is true. A piece of wire moving relative to a magnetic field will produce a current in the wire. The strength of the current depends on the amount of magnetic field and amount of wire.

As it happens, the above is just what is needed for a automotive spark ignition. Convenient, huh? What you need is system voltage, battery or generator voltage depending on starting or running, on the coil + terminal. If the coil - terminal is grounded current flows through the coil producing a magnetic field. When the ground connection is removed, no more current, so the magnetic field collapses. Perfect. Now we have a magnetic field moving relative to the coil, which has a secondary set of wire windings with more turns. The collapsing magnetic field induces a current in the coil secondary that goes out the coil tower to the distributor, which then deals it out according to seniority in the firing order.

Well, we can't just stand there grounding and un-grounding the coil, can we? Who has time for that? Hang on, if we had a switch in the distributor, that would ground and un-ground the coil for us. Brilliant! If we were really clever buggers we could use a transistor to do the same thing. But how to turn the transistor on and off? Use the switch in the distributor and call it the contact points. I know, we already know our electrical theory, so we can put a little coil of wire next to a magnetized ding-dong in the distributor to pick up the magnetic field and amplify that signal to turn the transistor on and off. We'll call the thing in the distributor the "pick-up" (heh-heh). Now, we put the transistor and amplifier in a box to control the ignition coil. Let's call that the "ignition control module". Man, we are on a roll.

According to our theory, we should have 12 volts at the + terminal on the coil with the key on. If so, everything up to that point in the circuit is good. We should then have voltage switching on and off at the - terminal of the coil with the engine cranking. If so, we should get spark out of spark plug wires, otherwise the ignition coil, distributor cap or rotor is fubar. No switching voltage at the coil - terminal means either we are not getting a signal from the distributor pick-up or the control module is not using the pick-up signal to turn the power from the coil on and off. Start your testing at the coil to split the system in two. That will tell you right away whether you have a supply problem or a switching problem.

Simple.

 

[Darthomas]

The two small connections are the primary circuit. The secondary connections are the center wire AND the case of the coil.
If the case is not grounded, you get no spark. Factory coil bracket should have a small pip sticking out to bite the coil through the paint. I learned this the hard way 35 years ago.

 

[TrailBeast]

ANY coil leaking oil is a bad coil, even if it does work because it wont for long.
The oil in coils is a coolant so when it leaks out the coil overheats and fails.

 

[TrailBeast]

The two small connections are the primary circuit. The secondary connections are the center wire AND the case of the coil.
If the case is not grounded, you get no spark. Factory coil bracket should have a small pip sticking out to bite the coil through the paint. I learned this the hard way 35 years ago.

That's not true at all of the stock style canister coils.
Coil cases do NOT need to be case grounded, and now I understand why you made the comment about changing anything from OE.
You need to do some more learning before you try to give advice.

 

[Darthomas]

That's not true at all of the stock style canister coils.
Coil cases do NOT need to be case grounded, and now I understand why you made the comment about changing anything from OE.
You need to do some more learning before you try to give advice.

When the current stops flowing in the primary, whether it is connected to points or electronic, at that instant, the coil has a connection to 12v ONLY. No ground.
The secondary has a path through the center, dist cap and plug, but needs a connection to the block (ground).
Pray tell what is the connection to ground for the secondary circuit at that instant?
I don't just make this stuff up, and hate to mention I was granted 2 US patents on an electronic device and wrote the patents myself. I'll provide the numbers if you'd like to read them.

 

[TrailBeast]

When the current stops flowing in the primary, whether it is connected to points or electronic, at that instant, the coil has a connection to 12v ONLY. No ground.
The secondary has a path through the center, dist cap and plug, but needs a connection to the block (ground).
Pray tell what is the connection to ground for the secondary circuit at that instant?
I don't just make this stuff up, and hate to mention I was granted 2 US patents on an electronic device and wrote the patents myself. I'll provide the numbers if you'd like to read them.

The spark plug which is grounded to the block is where that ground is for the secondary circuit.
That's how the spark gets there.
I must say, I am speechless, but please don't prove it to yourself by trying it.
I'll say this ONE time and drop it.
You are wrong, and other people that don't know don't need to think that busllshit is true.

 

[Darthomas]

The spark plug which is the grounded to the block is where that ground is for the secondary circuit.
I must say, I am speechless, but please don't prove it to yourself by trying it.
I'll say this ONE time and drop it.
You are wrong, and other people that don't know don't need to think that busllshit is true.

Yes, plug is grounded.
Now tell us how those electrons return through the block to the OTHER end of the secondary winding of the coil, creating a complete circuit for the secondary.
Go ahead, read the patents and come back, the numbers are 6982549 and 7071674.

 

[Bad Sport]

I removed the coil and noticed oil leaking from it. On the way to work took it to an auto part store they - told me it was good. I suspected not.

You suspected right, find a new parts store, lol.

On the way home I upgraded my multi-tester and the old coil was out of spec. Replaced the MSD PN 8202 coil with a coil for a stock 340 (all they had). Still no spark (as confirmed with my new spark plug tester in place of my old school grounding method).

A DC volt/ohm meter can be used to check the continuity of the pick-up coil. It can be checked at the leads as they leave the distributor. When measuring the resistance across the two leads of the pick-up coil you should see a 150-900 ohm reading.

Then with your leads in the same place, switch to AC and spin the distributor (either by hand or turn the engine over with the starter) you want to see 1 volt AC minimum.

Also check the reluctor gap AKA air gap, it should be checked with a BRASS feeler gauge, as the pickup is magnetic and a steel gauge can damage it. You are looking for .008 gap.

IF all of that looks good, bypass your ballast resistor (just for giggles ) using a piece of wire for a jumper. See if it starts.

 

[TrailBeast]

Yes, plug is grounded.
Now tell us how those electrons return through the block to the OTHER end of the secondary winding of the coil, creating a complete circuit for the secondary.
Go ahead, read the patents and come back, the numbers are 6982549 and 7071674.

I know exactly how it works.
Why don't you go out and try to figure out why you can hold your coil in your hand while your car is running.
That aught to keep you busy and confused for awhile.

 

[AJ/FormS]

Darthomas
Yeah you can remove the canister coil from its mount, hang it on a rubber bungie cord, and it will not affect the coil at all.
Why do you suppose that is? Well I'd tell ya , but then you wouldn't think about it.

 

[TrailBeast]

Yeah you can remove the canister coil from its mount, hang on a rubber bungie cord, and it will not affect the coil at all.
Why do you suppose that is? Well I'd tell ya , but then you wouldn't think about it.

With his theory you couldn't get slapped by a coil or plug wire unless you were in contact with the car itself to complete the ground, and I'd LOVE to watch the results of that test.
(Even with the coil out of it's bracket and not case grounded) LOL

 

[Darthomas]

If you are holding the coil in your hand, the electrons must flow backward through the positive 12v connection of the coil, ballast resistor, switch, ammeter AND through the battery positive side to reach ground of the block through the negative cable, definitely not the preferred or intended path.
That's a pretty good way to destroy an electronic ignition module and pick up.
Not to mention the ignition noise it makes in an AM radio.

 

[Darthomas]

And it also has to jump INSIDE the coil from the case to the primary winding, sorry, forgot to mention that.
But I don't have ignition problems or starting problems, I'm trying to help someone who does.

 

[RustyRatRod]

So now you say the engine WILL run with the coil not grounded? Make up your mind, Mr Patent.

 

[nm9stheham]

The ignition coil is an auto-transformer connection. When the coil - is ungrounded, the primary's magnetic field is going to collapse and supply the energy to the spark path, and will reverse the polarity of the primary voltage to keep the primary current flowing in the same direction so that the coil - goes to a few hundred volts positive and that will be referenced to 12 v direct at the coil + (or whatever is out of the ballast during the spark). My understanding is that there is no reference to ground except back through the 12v supply wiring.... and through all of the stray capacitance on the wiring everywhere and the field circuit for that matter... anything that connects to the blue IGN 1 wire.

There is no coil connection to the case. The secondary connections are the spark post and the coil -..... there are no other secondary connections. Interesting on the 'pip'.... perhaps it provides some sort of capacitive ground path but I am quite dubious that it provide any significant part of the spark current path.

(And yeah, I hold and MSEE and held a patent too that has long ago expired... whatever.)

 

[nm9stheham]

For the OP..... why do these things happen right before a car show for you ? LOL

If a coil is leaking it IS bad. Jesus, part of the definition of a good coil is that the oil is sealed in..... tell the parts store guys to get real.

OP, I have looked and we don't yet know what ignitionn systen you have. Is this the original Mopar electronic system or an older Mopar points distributor? Or an MSD system? If you don't know, take the distributor cap off and snap a pix and we can work from there. We really need to know what you have to be able to help.

 

[RustyRatRod]

Ok, then splain this Lucy. On a LOT of older cars, the ignition coil was wrapped in a cardboard cover and then put into the bracket. I have seen it like that on a MULTITUDE of non restored, original cars. In fact, on my old 63 M37 Dodge power wagon, the ignition coil itself was not grounded. It was in a waterproof can again wrapped with corrugated cardboard. I cannot COUNT the number of older cars I have seen where the coil body was NOT grounded.

Not trying to argue, because I am certainly no electrical genius, but this is what I have seen, first hand.

 

[TrailBeast]

Ok, then splain this Lucy. On a LOT of older cars, the ignition coil was wrapped in a cardboard cover and then put into the bracket. I have seen it like that on a MULTITUDE of non restored, original cars. In fact, on my old 63 M37 Dodge power wagon, the ignition coil itself was not grounded. It was in a waterproof can again wrapped with corrugated cardboard. I cannot COUNT the number of older cars I have seen where the coil body was NOT grounded.

Not trying to argue, because I am certainly no electrical genius, but this is what I have seen, first hand.

If he ever had seen the inside of a coil he'd know that there is NO connection from the coil windings or core either one to the case, as it simply holds in the cooling oil and protects the windings. PERIOD (on oil filled coils)
If he had ever held a coil in his hand with an engine running he would know that his theory is flawed.
(I hold ungrounded coils in my hand on a running engine all the time when test running HEI kits)
If he ever ran an engine without the coil mounted he'd know.
In fact I'm starting to think this guy is an alien pretending to be human at this point, and for the 35 years he said it was ago that he learned that I can only imagine there MUST have been others in his life that tried to explain that.
The only thing I can imagine at this point was that he argued and defended that theory till people gave up trying, or the only other people it came up around in that 35 years must have been, well, aliens also.
It just boggles my mind to have a "electrical whatever" with "patents" think that it works that way and defend it, when there is so much information out there that proves it to not be the case.
But he can go ahead and believe that for another 35 years for all I care, but telling another member that he won't have spark without his coil being gouged by the bracket for a ground is pure BS.

This is the FACTS, plain and simple, and no electrical genius is needed.
The primary field within the coil windings collapses when the voltage drops and that field collapse charges the iron core with a positive high voltage charge that is looking for a ground. (ANY ground)
When connected to a distributor with a rotor and spark plug wires it finds the closest ground path and that is the spark plug ground tab to the engine block, so the spark jumps that gap and ignites the fuel/air mixture and returns to the system via the battery ground.
The opinion that it is necessary to have a grounded case to build the spark is pure fantasy, not to mention completely wrong.

A COIL CASE DOES NOT REQUIRE A GROUND TO PRODUCE A SPARK.

 

[AJ/FormS]

Up until a few months ago, I believed a lot of things I had learned in hi-school were absolutely 100% true. Some of the lies almost made me cry.........