Partially bad coil pack?
Thread Starter
TECH Apprentice
Joined: Jan 2023
Posts: 340
Likes: 47
From: Corpus Christi, TX
Partially bad coil pack? So after getting my 2008 Silverado's 408 running I chased a random misfire that wasn't easy to reproduce to an ignition coil i swapped around 3 times just to make sure as the misfire would barely show up on the scanner.
I really couldn't find any definitive information online about a partially malfunctioning ignition coil and I also thought these type of things were all or nothing. In the process of diagnosing with an inline spark tester the coil even shows to function just as well as the others. The misfire was so random it wouldn't consistently show at idle and barely act up during load. It did have this funny region above 3k rpm where it almost made the engine seem like it was pinging. The tune misfire tables are desensitized.
I would love if someone was willing to test this coil for me just to confirm I am not crazy. If I do pull the trigger on buying an entire set of affordable coil packs where can I get them from without having to spend OEM money?
I really couldn't find any definitive information online about a partially malfunctioning ignition coil and I also thought these type of things were all or nothing. In the process of diagnosing with an inline spark tester the coil even shows to function just as well as the others. The misfire was so random it wouldn't consistently show at idle and barely act up during load. It did have this funny region above 3k rpm where it almost made the engine seem like it was pinging. The tune misfire tables are desensitized.
I would love if someone was willing to test this coil for me just to confirm I am not crazy. If I do pull the trigger on buying an entire set of affordable coil packs where can I get them from without having to spend OEM money?
Stick with GM coils. You will gain exactly nothing by going to aftermarket coil packs. Older SBC/distributor with one coil for 8 cylinders, yes, you'll gain performance. LS with a coil for every cylinder, you will gain nothing. Back in the earlier days of the LS1, some guys would swap the coil packs out for truck coil packs. This was due to them having a slightly higher spark output voltage, and was usually only done on turbo/blower engines. GM coilpacks are usually great. Go to a salvage yard and get some different GM, truck coil packs. That or swap out the suspect coil with one on the other bank. If the problem moves, it's the coil. If it doesn't, it's the wiring or something else.......
Joined: Apr 2006
Posts: 3,865
Likes: 1,122
From: Grand Rapids, Michigan
I bet it's not a coil. My Silverado had the same issue, replaced the coil, plugs, and wires, didn't fix it. Put a scanner on it and did a crankshaft variation learn and it instantly fixed it. If you have a new engine and the sensor was replaced or removed and reinstalled - You have to do the learn. It won't run correctly until you do.
TECH Fanatic
Joined: Dec 2017
Posts: 1,463
Likes: 265
From: Bossier City, Louisiana
As advised by Grinder11, go to the junk yard and grab a few original truck ignition coils and a few fuel injectors all of your same style and part number. This will be a very inexpensive trip and then you will have them to use when you need to analyze situations like this. Apply some five volt electricity and pressurized fuel injector cleaner to the injectors and they will likely be good as new.
Rick
Rick
Thread Starter
TECH Apprentice
Joined: Jan 2023
Posts: 340
Likes: 47
From: Corpus Christi, TX
The reason I ask is my truck has the round clear epoxy coils with no heatsink and I want to make sure that is what they should be. Don't think I have ever seen a part number on any of them either thought I should probably give them a closer look
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