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Discussion Starter #1 (Edited)
Hey guys, long time member, but forgot my password and no longer have access to the email I had on file. Anyway, I've been chasing a P0301 code and I'm about at my wit's end here, hoping you guys may have some ideas. Truck is a 2000 2.2 btw.

Problem started last year as a slight misfire, nothing too crazy but definitely noticable. Since it was almost winter anyway I put her into hibernation like I always do for the winter and figured I'd tackle it in spring. When spring came, again is wasn't bad so I drove it occasionally but the problem slowly started to get worse until eventually it was undrivable. My symptoms were very erratic RPMs, very aggressive engine studder and shake when stopped, and of course the P0301 code. I started with the plugs and that was of no help (Acdelco plugs) so my next thought was coil pack and here's where I get puzzled. I replaced the coil pack and that fixed the issue, truck ran like a top. However after a few weeks of driving the problem again slowly came back and as of today, again it's undrivable. So it was pretty obvious the coil pack fixed the issue, but it seems the coil pack has failed so I'm now wondering if there is a deeper issue that is causing the coil pack to toast itself. What would cause a coil pack to continuously fail?? Of course that's my hunch, it very well could be that it was a lemon but being Acdelco, I kinda doubt that. Also the misfires only happen when the engine is at operating temp, anything under that it idles fine.

Any ideas?? Thank you in advance!
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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wires-you disturbed them- then they moved back as you drove.or a crappy ground to that coil.
 

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It's mostly BS
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Agree with Jay. If the wires are old, replace them. The wires are supposed to be in a plastic conduit to protect them from shorting on engine parts, make sure yours is still there.
 

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Discussion Starter #5
Makes sense, thanks for the tips guys! I've got some time tomorrow so I'll update with what the results are.
 

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Discussion Starter #6
Well, it did turn out to be the spark plug wire. All I could get in a timely manner was a cheap AutoZone universal wire but that sufficed at least for diagnosing. Acdelco ones are ordered so I'll replace them all. I initially dismissed the wires as a visual inspection deemed them in great shape but just goes to show sometimes it's still worth doing the easy/cheap things first to rule them out. I tend to complicate things like that lol. Thank you all for pointing me in that direction, what you guys said about the wires made perfect sense.

And Bill, I hope you get yours figured out and it's as simple a fix as mine. I've spent hours researching misfire issues and know they can be a pain sometimes!! I gave myself a Max time and $$ limit with this issue. If it surpassed either of those I was just going to give it up and finally jump on the LS swap I've been planning for years. The 4 banger still lives on for now I suppose haha.
 

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B4U Task Force Admin
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Problem was solved in the post above yours.
 

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Not sure which year codes a P0301, but I had a similar problem with a 93. Can't always rely on codes to identify a problem, they miss it sometimes. The problem of missing after driving 5 miles one day got worse after I tried STP oil additive, problem increased and thought the engine is binding (more friction) maybe from sludge. So I changed oil with 30 weight (not 40 which is thicker), and it has been problem free so far. I see on the store shelf now newer conventional oils that have zinc or something to prevent binding, friction in older high mileage cars.
 
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