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Old 02-17-2017, 11:34 AM   #3
JFP in PA
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Join Date: Feb 2005
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Quote:
Originally Posted by Timco View Post
It's on my truck but same setup. I'm doing plugs but want to check those. Rough idle.

Is it good / bad or can you check performance?
There is a simple test for the coils to see if they are good or not. All you need is an ohm meter:

Resistance between terminal 1 and terminal 15 at 20°C: 0.3 - 0.7 ohms. Anything outside of this range is suspect.

Likewise on the spark plug connectors: Resistance: approx. 2 k ohms

One potentially misleading issue with static resistance testing: Coils often test fine on the bench, but then break down electrically under hot load conditions. So if the unit is suspect, test it on the bench, but then swap it with a another coil pack from the engine that is working correctly and see if the misfire moves to that cylinder. If it does, the coil pack is toast.
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