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I have a car that was misfiring really bad, so I changed the plugs and it’s better but it still misfire, some days more than others, it has cop but it’s an ecotec 2.2 and all the coils are merged into a long brick. How would I test something like that since I can’t just pull out one coil? From my understanding is that it cant be the icm because so far it’s only been cylinder one and the icm I heard affects multiple cylinders.
I also have an engine tick that goes away when the engines warm. It occasionally makes a metallic rattling but that could also be a look heat shield or something, I heard lifter tick is common but I also heard that the timing chain tensioner is sometimes an issue. I also have a stud broken on my exhaust manifold which I heard can also cause it. So I’m lost on how to narrow it down.
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Each coil has a primary and secondary side. If you unplug the ECM and measure resistance between the secondary (Plug Wire) to GROUND (Battery -) it should read the same for all coils. Same thing for the primary (low voltage side). BUT. Correct me if I am wrong but GM usually only has one coil pack for each pair of cylinders. Is that the case for yours? Each coil pack would be connected to two cylinders with both firing every 360 degrees turn of the crank shaft. One cylinder in the compression stroke and one in exhaust.
You should supply the codes if there is a CEL on.
Mine looks like this
https://www.google.com/search?q=2006+cobalt+2.2+coil+pack&client=ms-android-verizon&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoAmoVChMIkq-R5Mm9yAIVQpQNCh3otgVR#imgrc=tOo9IQNJA5yIHM%3AIs testing the same and I’m guessing I remove the icm first?
I see. The same theory applies but it does look like individual coils for each cylinder. One of the mounting bolts will be ground. If you have a multimeter, measure the resistance (OHMS) between each coil and ground. They should all read very close to the same maybe 4 to 20 K-ohms. Also check each of the primary connectors to ground (the small connector that the imc plugs into.
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