'97 Aurora - Cylinder 1 misfire (code P0301) - the Saga continues...

[mrbob]

I had the sparkplug and wire replaced and a few days later the same symptoms reoccur - surging, hesitation, misfiring, backfiring.

Why does this keep happening?

[Indy8]

Are you absolutely, 100% positive all the plug wires are in the correct position? It ran perfect for a few days? Genuine AC Delco platinum plugs and wire set? Carbon tracking can occur very quickly in non-matching sets and no one seems to know why. This happened to my car under warranty. The dealer replaced one new plug and one new wire because of misfire/tracking. Days later it came right back so I replaced all plugs and wires myself,... end of problem.

[mrbob]

Indy8, they are genuine AC Delco plugs and wires. The same Chevrolet dealer did a full tuneup about a 1.5 years ago and the wire that was just replaced was done under the wires' AC Delco lifetime warranty. Should I have to replace a another whole set of plugs after only 15-20k miles? Another shop is wondering about the ring(s)? on that cylinder. What are your thoughts? I am pretty clueless about much of this stuff (computer geek, not gearhead)

[Indy8]

The "100k miles on one set of plugs" thing does'nt always work, in fact, I have never heard of anyone actually doing it. I would change after 20k because it's cheap insurance and fairly easy. Do you have the tools to pull out one of the front plugs to verify that they are the platinum AC's and how dirty they look? I bought my car with 50k miles on it, from a dealer, and it had standard AC's in it. Hard to start, ran rough and got terrible mileage. I'm not sure the dealer put them in, but you never know and it makes all the difference. As does the silicone grease in the boots.

[GTP Dad]

I have to ask, are you sure the problem is with the same cylinder? You may have a random misfire caused by a defective set of plugs and wires. If the plugs haven't been changed, change them and look at the electrodes. If they are oily on cylinder 1 then you may have an issue with that cylinder but I doubt that is the problem. Once you change the plugs and wires I think this issue will go away.

If the mechanic insists on the ring issue, then have him do a compression test on the engine. If the rings are bad in one cylinder there should be a compression drop on that particular cylinder or at least a variation between cylinders. Of course that could also indicate a head gasket or valve problem.

The plugs and wires are the easiest and cheapest parts to change and will often cure many problems with misfires.

[Indy8]

I heard that!