Thread: Diagnosing corrosion on coil pack terminals

In reference to another thread, thought i would start this thread... here's some info that i've obtained over the years:


Distributorless (Simultaneous Ignition) Operation

Distributorless Ignition Systems and Direct Ignition systems that use one coil for two cylinders use a method known as simultaneous ignition. With simultaneous ignition systems, two cylinders are paired according to piston position. This has the effect of simplifying ignition timing and reducing the secondary voltage requirement.

For example, on a V6 engine, on cylinders one and four, the pistons occupy the same cylinder position (both are at TDC and BDC at the same time), and move in unison, but they are on different strokes. When cylinder one is on the compression stroke, cylinder four is on the exhaust stroke, and vice versa on the next revolution. (see Diagram)



The high voltage generated in the secondary winding is applied directly to each spark plug. In one of the spark plugs, the spark passes from the center electrode to the side electrode, and at the other spark plug, the spark is from the side to the center electrode. (See Diagram)

Typically, the spark plugs with this style of ignition system are platinum tipped (double platinum) for stable ignition characteristics.

The voltage necessary for a spark discharge to occur is determined by the spark plug gap and compression pressure. If the spark plug gap between both cylinders is equal, then a voltage proportional to the cylinder pressure is required for a discharge. The high voltage generated is divided according to the relative pressure of the cylinders. The cylinder on compression will require and use more of the voltage discharge than the cylinder on exhaust. This is because the cylinder on the exhaust stroke is nearly at atmospheric pressure, so the voltage requirement is much lower.

When compared to a distributor ignition system, the total voltage requirement for distributorless ignition is practically the same. The voltage loss from the spark gap between the distributor rotor and cap terminal, is replaced by the voltage loss in the cylinder on the exhaust stroke in the Distributorless Ignition System.

now, onto the theory and science behind the corrosion of alternating coil terminals...

Presuming that the contacts in the plug wires and the coil terminals are not of completely the same metals, the possibility exists for galvanic corrosion (or two metal corrosion)

This reaction is typically present in places where there is an electrolyte (i.e. a battery) but there can indeed be enough moisture/other elements in the atmosphere for this to occur in the engine bay. -- here's how it goes --

When two or more different sorts of metal come into contact in the presence of an electrolyte a galvanic couple is set up as different metals have different electrode potentials. The electrolyte provides a means for ion migration whereby metallic ions can move from the anode to the cathode. This leads to the anodic metal corroding more quickly than it otherwise would; the corrosion of the cathodic metal is retarded even to the point of stopping. The presence of electrolyte and a conducting path between the metals may cause corrosion where otherwise neither metal alone would have corroded.

Originally Posted by SyntheticShield

Ouch, I think my head just exploded!

Just kidding. That is some very good information. I dont know where you get that stuff from but good find. So literally the corrosion could occur on any of the terminals? I wish we had some type of database going as to who all has experienced this, on which terminals with which coils, at what mileage and so on. Im not purely a numbers person, but you can get a very good starting point from the numbers. Where the numbers fail is in common sense, but thats another post all together. But if we had some numbers to start with, we could look for patterns and such and maybe come up with a solution.

And you KNOW it has to be happening on other vehicles with distributorless ignition. Maybe this has been solved though with the coil on plug set ups.

i think the reason it's seen on only one terminal on each coil pack is because of the current flow, one being an anode, the other a cathode.

Originally Posted by SyntheticShield

Well mine was only on one terminal of one coil pack. All the others were fine. My friends L67 Regal was the same way on #3 I believe. My bosses L36 Bonneville was bad on one of them and a little on a few others though.

Maybe we need to start documenting this kind of stuff and see if there is a solution. I believe you are correct, we just need to see if there is any practical solution and develop the data to prove that that is the cause.

probably one of the easiest fixes is using dielectric grease.

Originally Posted by SyntheticShield

That could be a good solution, but I have always had concerns about it reducing electrical conductivity. Would that be put directly on the terminals? Any information on its resistance and so forth. Normally that probably wouldnt amount to much, but with the ignition system resistance of any kind has a profound impact on the amount of power getting to the spark plugs.

I have an article in the How To section on side gapping spark plugs in which I wrote some equations that show the impact the resistance of the plug wires can have on the amount of energy getting to the plugs.

it would inded, be put on the terminals. Dielectric grease isnt conductive, but insulative. when putting on the terminal ends, the dielectric grease is pushed away from surface contact, thereby surrounding/insulating the contact points.

that being said, if that's a concern, there's another alternative for you...

it's called OX-Gard, from Gardner-Bender. I could ramble on about it, but this article i read online sums it up very well...

OX-GARD, made by GB Electrical Inc., is the best-kept secret in the electrical industry, because it has indispensable applications in the automotive world too. It is an anti-oxidation compound (a conductive grease-like substance) that electricians use on electrical connections, as well as conduit connections, and other places where copper and/or aluminum join, that are exposed to the elements and need lasting protection.

It can be used throughout the electrical system in vehicles, especially under the hood. I use it on all my crimp-on connectors, by applying it to the wire before I attach the connector and crimp it on. Then I put it on the connector as well before I slip it into place. This insures a good, long lasting and trouble free connection.
There is some confusion between OX-GARD and the more common dielectric grease products. So let me clear it up. Basically OX-GARD conducts electricity, dielectric grease does not. Dielectric (translated to layman's terms) means insulation. It provides excellent protection against moisture, but since it doesn't conduct electricity, it can not improve the connection itself. When you use dielectric grease, it is forced out of the point of contact in the connection, and thus does not interfere with the flow of electrons, but fills in the air gaps and keeps air and the elements out. This is great for new connections, but it does not promote conductivity of the connection itself, and so will not help with an older connection that has developed even the slightest corrosion or oxidation. OX-GARD is impregnated with fine abrasive metallic particles that bite into both surfaces improving the connection between the contacts, and promoting current flow through what would normally be small voids between the two surfaces, effectively increasing the total surface area of the contacts, reducing resistance, and allowing more current to flow through the connection.
This reduced resistance translates directly into a cooler more efficient and reliable connection, especially in high current applications like your battery posts, alternator terminals, high output headlight/driving light wiring, high watt stereos, winches, etc., which means brighter lights, louder stereo, even longer winching times, because you are not wasting power through a poor connector. The only advantage of dielectric grease over OX-GARD, is the fact that it doesn't conduct electricity, so you can slather it on without worry of shorting out adjacent conductors, like found in a multi-pin connector. This is why you need to be careful with OX-GARD, and only use it sparingly, being careful not to get it on anything else but the connection itself. Think of it as a solder grease, and don't short anything out with it. If you are applying it to small pins and sockets of a connector, use the large end of a flat toothpick and carefully apply to the contact surfaces, and just wipe away any excess when your done, and it will be fine. Also, when applied to older connectors, its abrasive properties will actually help "sand" away the corrosion you can't get out by cleaning, and by working the connector on & off repeatedly, you will be able to improve an otherwise poor connection.

Originally Posted by SyntheticShield

Oh Lordy, that sounds like the perfect solution. I need to search on where to find that stuff. That has TONS of applications. Thank you for posting about that. I take it you have used it before?

And sorry about the dielectric grease, I dont know what I was thinking that it would be conductive. Duhhhh. Ive had electronics training, really.

i've not personally used it, but have seen many people use it.. just not had occasion to use it yet....


anywhoo... most hardware stores should have it, if they carry G-B products, in the electrical section, probably near the electrical tape/wire nuts. -- a google shopping search shows lots of places online to get it, too. (search for ox-gard)

if the hardware store doesn't have it try a ham radio supply, that is what they use on antennas

didnt know they made radios out of meat




lol there are not many places anymore where you can get ham radio stuff.

Originally Posted by SyntheticShield

Oh man, I dont even know what to say to that one. No soup for you!

you can make a battery out of a potato, though....


hehee

order from the internet, shipping should only be a couple dollars