What should the secondary resistance be on my coil pack?

I am sooooooo frustrated! I have a 1999 ford taurus 3.0 ohv (vin U). I have an engine misfire problem occurring most noticeably at idle. The MIL is lit and says its cylinder 1,2 and 5. Now Ihave been trying to diagnos this for weeks. I have conducted multiple tests and I have boiled it down to either ignition system or fuel system. I started with the ignition system first, and when I got to the coil pack the secondary was out of specs according my haynes manual. I take it off and run it down to autozone to make sure they get the same. They do but... there chart says its in spec cause the chart shows it should be 10.5k-16.5k. So now I was confused, so I had them pull the new one they had off the shelf and see where it was. It was at 10.8k. So I said ok I am not sure mine is bad and wont spend 75$ on a gamble. My secondary is 13.67k when cold and 15.7k when engine as just come back from a drive. And to make matters more confusing, the repair guide you can review online at autozone.com for your vehicle says secondary should be 12.8k-13.1k. Which is weird cause then that means the one they have on there shelf is bad!!!! Oh yeah and haynes says it should be 13.6k respectively. I have been digging online and can't find anything. For the love of god, who is right and who is wrong. Also if anyone knows, is it normal for my secondary resistance to differ vs. hot or cold like mine?Thanks.What should the secondary resistance be on my coil pack?
The resistance specs are not that all critical when they are somewhat within range.The important factor is whether the coil is conducting or not,as in an open or shorted condition.The only way to prove the operation is with it in use while generating a high voltage that the meter cannot read.An oscilloscope would paint a better picture.As already suggested,try connecting a spark plug and watch for a healthy spark.What should the secondary resistance be on my coil pack?
The secondary resistance can be any of those depending on the vendor and the production run. As long as it is firing at all you can't learn much from the resistance; if the secondary shorts the spark will suffer a lot worse than the resistance. If you get one that doesn't fire at all but has 5.8K resistance you can be sure it is bad, or if you get one that measures 88K you can be sure it is bad. Other than that the resistance really doesn't tell you much. It is normal for the resistance to rise significantly when hot because of the positive temperature coefficient of the copper wire - about 0.4%/degree C. A 37 degree C (67 degree F) difference would produce the change you saw, and that sounds just about right.



A better test is to put a spark plug in the receptacle and ground the shell, then see what the spark looks and sounds like. If you get a fat blue spark snapping across the spark plug it is good. If it is an orange spark with a puny click you can hardly hear the coil pack is bad.



I'd go for the fuel delivery first because you mention it is worse at idle. Weak ignition is almost always worse under load, as the spark voltage goes up when the combustion chamber pressures rise. Some shops, and even some larger parts stores, can flow test fuel injectors. I recommend trying a bottle of fuel injector cleaner in the tank and driving 200 miles before going to that expense, but that is the way I'd bet.