P0300 Still there, after cap rotor

[OilBurner2003]

This is going to be a part two to my previous post, I replaced the cap and saw no significant change. I decided to say screw it and wanted to look at the condition of my new AC DELCO plugs, which are only 6 months old. Well, popped one out, found this. Now to me, that looks fouled. Fouled enough to cause a misfire? I'm not sure, I'm sure someone on this site with more knowledge than me could tell me. If it's as bad as I think, it's only a 6-month-old plug that has maybe 200 miles on it. So... What the hell? My cap was toast, and my plugs look bad. Now this plug also looks like it has oil on it, from a leaky valve cover from what I've been told. I think my problem was I had a bunch of leaks and broken parts I didn't know about until AFTER I did the cap, rotor, wires, and plugs. Maybe that prematurely helped with breaking my cap and plugs? I had a guy tell me to look at the vent screen under the rotor, which I will do. But that's the end of my problem-solving ability's. I'm going to change the plugs because they all look like that and see if those change anything. If not, I'll send it to a mechanic and have him find the problem. Hell, it could even be my injectors at this point, I have no clue how to check them. Any and all advice is greatly appreciated! Wanted to say, this problem started 6 months ago after we replaced the wires, cap, rotor, and plugs. So, something really makes me think we got a bad part somewhere. Update! Found a bad spark plug wire. Put my head down low to engine to hear how it was sounding, I could hear an electrical arc! It was zapping the exhaust manifold and burned through. It must have come loose from its fastener somehow. This must have been the problem, or at least the most major one. Will replace and update on the condition once replaced, thanks everyone! Although it doesn't explain multiple cylinders misfiring, it's a great start.

 

[Fless]

I don't see anything wrong with the plug, the electrodes are clean. If you have a leaky valve cover the oil wouldn't get into the cylinder, it'll stay on the outside of the plug. That won't necessarily cause a misfire.

 

[OilBurner2003]

I don't see anything wrong with the plug, the electrodes are clean. If you have a leaky valve cover the oil wouldn't get into the cylinder, it'll stay on the outside of the plug. That won't necessarily cause a misfire.

Ah, thank you for clearing out that valve cover thing. I did wipe the electrode to inspect the material, but what you said opens up more possibilities then. Then It's probably a problem out of my league then, will do some last-minute checks before I have someone else take a look at it. Thank you!

 

[OR VietVet]

This post is in the wrong section, for one. The plug looks fine, IMO. If enough oil leaks from a valve cover and damages the wire, then you can have a miss but oil around the base of the plug, where it threads in, will not cause a misfire, that I have ever seen. AC Delco cap and rotor, correct? I seem to remember from the other thread that they are. Did you do a wet and dry compression test?

 

[OilBurner2003]

This post is in the wrong section, for one. The plug looks fine, IMO. If enough oil leaks from a valve cover and damages the wire, then you can have a miss but oil around the base of the plug, where it threads in, will not cause a misfire, that I have ever seen. AC Delco cap and rotor, correct? I seem to remember from the other thread that they are. Did you do a wet and dry compression test?

I have not done any compression tests; I am going to go test each spark plug wire with a multi meter and also just see if there's anything staring at me in the face like a burned/cut wire. I thought engine and drivetrain was a good spot to post this lol. I will also research how to do a compression test, I don't have the tools at the moment, but that's a good thing to look into.

 

[OR VietVet]

I have not done any compression tests; I am going to go test each spark plug wire with a multi meter and also just see if there's anything staring at me in the face like a burned/cut wire. I thought engine and drivetrain was a good spot to post this lol. I will also research how to do a compression test, I don't have the tools at the moment, but that's a good thing to look into.

You posted in 2021 and newer section. You have a much older rig. Find that section and then of course, the Engine and Drivetrain is correct. Perhaps a mod can fix this and move it. @Fless, can you please help.

 

[OilBurner2003]

You posted in 2021 and newer section. You have a much older rig. Find that section and then of course, the Engine and Drivetrain is correct. Perhaps a mod can fix this and move it. @Fless, can you please help.

Huh, strange. Apologies.

 

[OR VietVet]

Huh, strange. Apologies.

No need for apologies here. Just pointing it out that if in wrong section, the right people will not see the post and you get left with no answers. It all comes out in the wash eventually. I did reach out to @Fless, a moderator, to switch it to correct section.

 

[OilBurner2003]

No need for apologies here. Just pointing it out that if in wrong section, the right people will not see the post and you get left with no answers. It all comes out in the wash eventually. I did reach out to @Fless, a moderator, to switch it to correct section.

appreciate it! You and the rest of this site have been a great help.

 

[Fless]

You posted in 2021 and newer section. You have a much older rig. Find that section and then of course, the Engine and Drivetrain is correct. Perhaps a mod can fix this and move it. @Fless, can you please help.

Moved.