Shorted coil?

02 Town Car, 4.6L with individual coils.
Had a hard time starting it last week (very unusual). It ran a bit rough for a few seconds, then smoothed out. Everything seemed fine,
but the service engine light stayed on, so I made an appointment to get it checked. Also, part way back to Michigan from Florida early last week, it seemed a tiny bit doggy but ran just fine. I chalked it up to imagination. Got 25.3 mpg for the 3200 mile trip, btw.
Anyway, got it to the dealer yesterday. They checked the codes & found the # 7 coil shorted & replaced it under warranty. I'm glad of that because the coils are $ 121.00 each! Anyway, the car's great now; more power than I can remember it having.
QUESTION - it ran fine with a shorted coil??? I'd think a shorted coil wouldn't work at all & I'd be driving on 7 cylinders, yet it ran smoothly. I guess it could have been partially shorted & giving a weak spark, but who knows. I wish I could have gotten the old coil so I ould check it with a meter, but they kept it since it was a warranty job.
What does the group think; partially or totally shorted?
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On Wed, 09 Mar 2005 09:51:28 -0500, David Starr wrote:

It sounds like there was at least some spark on that cylinder, but the coil had some sort of internal problem that was keeping it from working properly. Take what the tech told you with a grain of salt -- he probably did not spend time determining exactly what the problem with the coil was. Once he found it was the problem he just replaced it. Also, a lot of people misuse the word "short" to describe any electrical problem.
A related question for the group: can someone explain the advantages of COP ignition to me? It should theoretically allow for higher voltage spark and wider gaps, but is it being used for this reason? Any thoughts on the long-term reliability of COP ignition?
Rodney
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wrote:

That's why I wish I could have kept the old coil.

Very true. A dead short can have dangerous and spectacular results.

At $ 121.00 per coil, I sure hope it's reliable! I'm speculating, but I'd think the benefits have to be quite high to justify the higher cost to the manufacturer.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Dave Starr, Senior Shop Rat Emeritus: 14,647 days in a GM plant. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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