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Ignition Coils

My husband’s 2001 Buck LeSabre had an ignition module and one ignition coil replaced in March. Yesterday, the car broke down, and the mechanic told us that the new ignition coil shorted out the other two coils. Is this believable? We’ve been using the same mechanic for several years because we trusted him and have heard a lot of good things about him, but this seems kinda fishy. Oh, and this car is not one of the GM cars that was recalled.

It depends on where he gets his parts. I only use Napa or OEM parts. Have him use either of those and you’ll be fine.

It would be interesting to see this proven how one coil takes out the other two mounted on an ignition module. I myself don’t believe it. Module maybe, other two coils nah.

If your mechanic can figure out what is wrong and get your car running again, that’s the best you can hope for…

The other two coils may be bad, and it could be that it was just their time, but the coils are wired up in parallel so they do not affect each other.

In series wired circuits, one component can take out some others under certain conditions, but not so with parallel circuits.

I’ve seen this logic used in light fixtures where there are two or more bulbs. As soon as one goes out and is replaced, the others start going out. Some people believe the new bulbs are taking out the older ones, but its simply that they all started off together so the bulbs will burn out relatively close to the same time, the new bulb did not overload the old one.

The mechanic’s story is bologna, but he may actually believe it. He’s probably seen this numerous times before and never really understood why.

Coils are mass manufactured by the millions under very controlled manufacturing conditions. One coil is almost exactly the same as the next, as close to it as the manufacturer’s engineers can possibly make it. That lack of variability is the only way to cost effectively mass manufacture things like coils. Thus, their lifespans when subjected to exactly the same operating conditions are extremely close. When one goes down, chances are the others will follow. Many, myself included, prefer to change them all out when one goes, knowing that the others are soon to follow.

I recently had a front coil pack go on my 2000 Maxima. The on-line parts place I usually go to said that the still-working ones were likely to fail sooner or later and recommended that they all be replaced - a very pricey proposition!!!

@sparkymeb, you could opt to replace one at a time as your budget allows, but you’re running a gamble that your budget will buy a coil before the coil croaks.

With all thing being equal, all the coils should go out close to each other. One coil can go bad long before its brethren. If you have a bad spark plug, it will damage the coil.

Once the voltage builds up from the collapsing magnetic field, the current has to go somewhere. If it can’t find an external path, like the gap at the tip of the spark plug, then it has to go somewhere else. That usually means that it arcs across the layer to layer insulation inside the coil.

In the old days, coils were insulated with oil so any arc ing was self repairing. Todays coils are insulated with epoxy and do not tolerate a misfire very well.

The point I am trying to make is, how old are your spark plugs?

Thank you all for your views. My mechanic doesn’t like to replace things until absolutely necessary because he doesn’t want us spending more money than we have to. So maybe that’s what he was thinking.

He sounds like a decent guy.

He may believe that if one coil goes out the load placed on the other coils increases, but that’s an erroneous conclusion. Each coil individually is subjected to the same voltage even if one is down, and its load is determined by the resistance it has to overcome in the discharge (spark). Each on is determined by its own individual “circuit” characteristics (the spark plug, the ground, the cylinder temperature, the compression and fuel mix) and one does not affect the other. It’s those things, the things that the induced voltage must be able to overcome, that cause the cylinder’s discharge pulse to be whatever it is.

It’s also possible that he was speaking from historical experience. In the days of single coils, changes in cylinder spark loads all affected the same coil, so any effect from one cylinder automatically affected the coil for all the cylinders. In the later days of coil packs, heat transfer from one misfiring coil could affect its neighbors. Even coil insulation breakdown could affect a coil’s neighbors.

Or he may have just had a rough day and misspoke. I wish I had a ten-spot for every time I’ve done that.