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Hi, everyone, this isn't a current issue for me, but something that's been bothering me because I can't figure it out.
Short version - can changing a single coil cause temporary misfire on all cylinders that clears after driving for a while?
Long version-
I battled misfires with my 97 Firebird last summer that resulted in a plug/wire change. That improved things, but it still felt like it was a little off. I watched it on my LS1M and noticed that it was still misfiring a little, not bad enough to throw a code, with most of the misses on the same coil. So I grabbed a cheap coil at Autozone to swap in to see if that changed things. It did, they were worse. This time it was misfiring at random intervals on all cylinders - again, no codes, just sounding really bad and running rough. This was the first time I'd ever done a coil change, so I thought maybe I'd screwed something up, and took it to the mechanic I was using. He called me the next day and told me to come get the car, there was nothing wrong with it.
I slapped the scanner back on it when I picked it up, and sure enough, there were a few misfires, then as I drove it a few more miles, none. I watched it for a few more days, but it stayed clear.
I DID notice that after I changed the coil and hooked the battery back up and took the car for the first test run, it was missing like crazy. I spooked and drove it straight home before I got too far down the street. When I started it the next morning and drove it to the shop, they were fewer and fewer, and I guess by the time my mechanic took a look, the number of misses was negligible.
So basically - misfires on two cylinders, changed the coil for those two cylinders, misfires EVERYWHERE for about 5-10 miles, then running clean. Is this common? Could there something else wrong that's laying in wait? I had thought that maybe I'd knocked something loose when I was wrestling with that back coil, but my after underhood matched up with the before pictures I usually take before I take anything apart (heh). I don't drive much anymore, but the car's not given me any more firing type problems (yet) since that little adventure.
Sorry so convoluted, but this has really bothered me and no one I've talked to has any ideas what might have happened, and I definitely don't since I only have a vague idea of what I'm doing when I approach the cars with hand tools and beer. I think my Monte Carlo is ready for new coils, but I'm not ready to start swapping those out until I've figured out what might have happened here.
Short version - can changing a single coil cause temporary misfire on all cylinders that clears after driving for a while?
Long version-
I battled misfires with my 97 Firebird last summer that resulted in a plug/wire change. That improved things, but it still felt like it was a little off. I watched it on my LS1M and noticed that it was still misfiring a little, not bad enough to throw a code, with most of the misses on the same coil. So I grabbed a cheap coil at Autozone to swap in to see if that changed things. It did, they were worse. This time it was misfiring at random intervals on all cylinders - again, no codes, just sounding really bad and running rough. This was the first time I'd ever done a coil change, so I thought maybe I'd screwed something up, and took it to the mechanic I was using. He called me the next day and told me to come get the car, there was nothing wrong with it.
I slapped the scanner back on it when I picked it up, and sure enough, there were a few misfires, then as I drove it a few more miles, none. I watched it for a few more days, but it stayed clear.
I DID notice that after I changed the coil and hooked the battery back up and took the car for the first test run, it was missing like crazy. I spooked and drove it straight home before I got too far down the street. When I started it the next morning and drove it to the shop, they were fewer and fewer, and I guess by the time my mechanic took a look, the number of misses was negligible.
So basically - misfires on two cylinders, changed the coil for those two cylinders, misfires EVERYWHERE for about 5-10 miles, then running clean. Is this common? Could there something else wrong that's laying in wait? I had thought that maybe I'd knocked something loose when I was wrestling with that back coil, but my after underhood matched up with the before pictures I usually take before I take anything apart (heh). I don't drive much anymore, but the car's not given me any more firing type problems (yet) since that little adventure.
Sorry so convoluted, but this has really bothered me and no one I've talked to has any ideas what might have happened, and I definitely don't since I only have a vague idea of what I'm doing when I approach the cars with hand tools and beer. I think my Monte Carlo is ready for new coils, but I'm not ready to start swapping those out until I've figured out what might have happened here.
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