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Discussion Starter #1 (Edited)
I went to AutoZone.com - Get in the Zone! and found that an ignition coil for my '98 is about $80
It looks like this....
aecontent_autozone_com_znetcs_product_info_en_US_wl2_C901_image_6__.jpg

Note that there are six lugs in pairs.
Essentially there are three coils in the coil pack. Any one of them can go bad.
One pair of them supplies your number 1 and number 5 cylinders.
Edit (pairs are 1-5, 4-3, 2-6)

The number one cylinder is the one that is on the passenger side closest to the firewall.
The number 5 cyl is the middle one closest to the radiator.
The coil pack is difficult to get at, however if you remove the plastic part of the hood that holds the winshield wiper assembly it is easy to get at. That plastic part is really easy to take off... ten minutes.
What I would do is, push in on the wires to make sure they are fully seated, if they are and it still runs like crap, If I didn't have a volt meter, would buy the coil and put it in. IF I had a volt meter, I would test the windings. And if proven bad.. put it in.
In the next slide I'll tell how to test the coil with a digital voltmeter.
 

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Discussion Starter #2 (Edited)
Your connector to the coil should have four pins in it, see the photo above.
One is the B+ pin, the other three are the (-) pin for each of the three coils in the coil pack.
You should disconnect the connector and test the ohms between the B+ pin and each of the other three pins. The ohms should be the same for each check and be between 0.3 and 1.0 ohms.
Then you should pull the plug wires from the coil in pairs... only do two at a time!
check the resistance between the big lugs of the coil
They should be between 6.5K - 11.5 K ohms.
When you pull the plug wires off, place them so that you know which one goes back where.
IF your resistance readings are different, then you need to replace the coil pack.
Remember, your coil pack is like three separate coils in one. The readings of each should be reasonably similar to the others.
 

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Are these ignition coils as reliable as can be? I have yet to replace one ever, not yet on my 98 or 2000 windstars. Seems to be a great design for reliability unlike the individual coils for example on 2003 E250 van, replaced almost all 8 within 7 years on a fleet van.
 

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Discussion Starter #4
LOL... so far so good for me too! :)
 

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OK, #3 is missing. I have an old gap indicator that I put between the coil and the sparkplug wire. It's not sparking at all. It's like it's not getting the signal from the PCM. Is that possible? If I ground the output through the indicator, I get a very small spark which I assume to be the waste spark from the opposite cyl, although when I open the gap, the spark stops and the other cyl doesn't miss.

It all ohms out good. I hate to sink $100 into Autozoner if it's for nada. Suggestions, quick??
 
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Before buying a new coilpack, I did the Poppy checks above, and the old one passed with nominal readings. Unless there's some sneaky circuitry inside it, like spark gaps you can't measure, I don't know why, but the old one is bad, and the new one works a charm. Its resistance measurements were about the same.

Windy purrs again.

GB
 

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Verify Coil's Primary to Secondary Isolation too....

There's no circuitry inside the modules other than three transformers.

Primaries are tied together on one end and connected to B+. Then the other end of the primaries go to the PCM, which grounds them and release them in sequence to produce the spark on two spark plugs simultaneously.

The magnetic field from the primary coil of the transformer's drive the Secondary coil which elevates the potential to a high voltage. Each end of the three secondary coils is connected to one of the six high voltage sockets on the module.

One spark is produced by negative high voltage and the other is produced by positive high voltage. I believe the reason for the wire's rubber boot being different color (and material) on opposite sides of the engine is for ozone-protection on the positive spark side of the engine. One side is black and the opposite side is grey. (I learned this by working on TV's, whose rubber isolator is usually grey).

Secondary coils are physically separated from the Primary coils, so no resistance reading should be obtained when testing resistance between them with a multimeter.

Now the reason why my Windstar 98 would run roughly with strong fuel smell out the exhaust, and give me codes Misfire #3 and Cam Sensor failure:

Each secondary coil would read approximately 12Kohm each. Primaries were about 0.3 ohm each too. So far so good according to the tests suggested on this thread.

When testing for isolation between primary and secondary coil which drives cyl #3, there was actually a reading of about 12Kohm between them, when the reading should show an open circuit. This meaning that the spark for cyl #3 was being sinked through the primary and then on to B+.

So, no spark on cyl #3, and a BIG spike of noise through B+ towards anything connected to B+, (just about everything). Therefore driving nuts the PCM and confusing a B+ spike to a mis-triggering from the Cam sensor.

Coil Pack was replaced. Engine runs smooooooth, and no code for Cyl #3 misfire of course, and Cam Position Sensor code magically disappeared.

Happy-Wife, Happy-Ending...
:smile5:
 

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Thans, Amaury. I still have my old coilpack, so I'll check it for leakage, too. I suspected a spark gap limiter inside that had gone bad. Don't think I checked for leakage.

GB
 

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Finally got a chance to check my old coilpack, as noted above, and there is good isolation between primary and secondary. In other words, it's a different failure than amauryt experienced. If I run across my old megger someday, I'll re-check it. A megger uses about 500 volts to check breakdown of wiring - and components designed to take it.

GB
 

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The way you offer is to check low voltage coil only. To check all the pack run engine when it is dark. you can see sparks in places of bad insolation
 

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Finally got a chance to check my old coilpack, as noted above, and there is good isolation between primary and secondary. In other words, it's a different failure than amauryt experienced. If I run across my old megger someday, I'll re-check it. A megger uses about 500 volts to check breakdown of wiring - and components designed to take it.

GB
500 V is not enought. W/O spark plug coil generates over 50 kV, and it is not a tazer, it is really dangerouse thing (no current limitation, no power limitation). This coil may easyly shock and kill. So be carefull.
 
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