As I like to have a preventative maintenance program for my 2001 S80 2.9L, I want to test my coils to see if they're still good.
Do they slowly fail or just quit?
I tested three coils by probing the four contacts. Mind you, I was just randomly testing/playing and saw that two coils had very similar values registering. The third one was registering a higher number. So something is wrong.
Out of these three coils, do I have to replace one or two of them?
Any testing procedures out there?

 

the engine will run rough, and you will get a specific code, dont waste money unless its broken

 

My experience with a coil going bad has been like the experiences of other members who have dealt with this. The coil goes bad and the engine begins to misfire and run rough. Many people have also had an emissions warning appear which is due to the unburned fuel being dumped into the exhaust. A bad coil is easy enough to replace.
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what are some indications or symptoms of a bad ignition coil? I think my car is getting some leak of some sort.. is it connected to it? Thanks.

 

>> the engine will run rough, and you will get a specific code,
>> dont waste money unless its broken

But once it is broken, or a lot of things are broken - how do you know what to do? P0305 will suggest a bad coil (or several other problems) with #5, but if it arrives at your door with P0300 the problem could be anywhere. A proceedure to test the coils would be very useful, so would a proceedure to test the car at the coil connector.

THe ability to test components and signal/supply connections directly is extremely useful and greatly reduces the time and expense of the "hunting and hitting" technique of repair practiced by parts swappers who masquerade as mechanics.

How DO you test a coil? See how long a spark it will throw onto the cam cover? or will this kill a good coil?

 

If its running rough at idle you can test it by pulling the injectors from each cylinder for a couple of seconds in sequence. If the engine note changes, that cylinder is working fine. If there is no change, then thats likely where you have a coil problem.

If you have multiple misfires, buy one new coil and use it to isolate the others.

I tried to test for resistance on my coils and got zilch. Other than that its hard to really test them. Luckly they usually fail in a manner that makes it easy to detect at idle.

 

You can't truly test a coil with any great results unless doing under true voltage and load. You can confirm continuity and resistance at passive stave easily enough, clean contacts and springs for reseating, etc... I've done this on all when I manage to bonehead two with water. I went ahead and replaced all six. All diagnostics were good with continuity and resistance but the voltage would not be there or is too retarded for proper firing of the plug. I have four good spares if you need a replacement...

 

Hi. My daughter has a 1999 volvo s80. The other day it started to run rough and it smelled like rotten eggs. We dropped and cleaned the Catylitic converter, replaced the mass air flow sensor and the front O2 sensor on the drivers side(as per the code the car was throwing). Then we found and coil pack not firing and replaced it and all the spark plugs too. (car has 153,000 miles on it). It will run great for a few minutes, then start to run rough again. Each time we check we have another coil pack that isn't working. Is it normal to blow 3 coil packs back to back like this, or is there something else triggering this. Please help. We just don't want to continue to throw money at the wrong problem.

 

I have 3 or 4 working coils for cheap if you need them...