How to accurately test ignition coil pack

[mikepier]

I have a 99 XLT, I'm trying to troubleshoot a slight rough idle problem. I suspect it might be the coil pack. I tested it according to the Haynes manual, it says you should get this:

Terminal 3 (coil 1)-spark plugs 1 and 5
Terminal 2 (coil 3)-spark plugs 2 and 6
Terminal 1 (coil 2)-spark plugs 3 and 4

If the resistance for all of the readings was between 6,500-11,500 ohms, the ignition coils are OK. If any of the readings was less than 6,500 ohms or more than 11,500 ohms, replace the corresponding coil pack.

But I'm consistently getting a reading of more like 13,000 ohms on each terminal. Is this normal? Anyone else get the same readings?

 

[BrooklynBay]

If Haynes says that it's out of spec, and you are experiencing a rough idle, then I think this might be the answer. Check the resistance of a new coil before you buy it to compare your readings.

 

[mikepier]

If Haynes says that it's out of spec, and you are experiencing a rough idle, then I think this might be the answer. Check the resistance of a new coil before you buy it to compare your readings.

Thanks, I think I found my problem. Was not the engine at all, it was the muffler. look for my post on how I found it.

 

[BrooklynBay]

Thanks for the update!

 

[Orleans]

I have a 99 XLT, I'm trying to troubleshoot a slight rough idle problem. I suspect it might be the coil pack. I tested it according to the Haynes manual, it says you should get this:

Terminal 3 (coil 1)-spark plugs 1 and 5
Terminal 2 (coil 3)-spark plugs 2 and 6
Terminal 1 (coil 2)-spark plugs 3 and 4

If the resistance for all of the readings was between 6,500-11,500 ohms, the ignition coils are OK. If any of the readings was less than 6,500 ohms or more than 11,500 ohms, replace the corresponding coil pack.

But I'm consistently getting a reading of more like 13,000 ohms on each terminal. Is this normal? Anyone else get the same readings?

Hi,

I used this image for the test and the figures obtained were not accurate, they were swinging, it's normal?

Thanks