Dave M

I sent out my PCM to get tuned. Once I got it back I reinstalled it and went for a drive. After 35 miles I got an SES light. Once I got home I could hear a rather loud ticking sound coming from the engine bay with the engine running. I pulled the code and it was a 303 - Misfire detected in cylinder 3. A couple days later I went out for another drive to see if I could recreate the problem to do a little more diagnosis and this time after just a couple miles I got the SES light again.

I couldn't really detect a noise this time, and when I pulled the code this time it gave me a cylinder 1 misfire. I popped the hood looking for arcing from the plug wires. I couldn't see any but they are wrapped in insulation. I could detect a diffuse flash coming from the coil. I have an MSD coil and the arcing appeared to be coming from between the coil body and the metal housing (bar) that surrounds it. I could only detect the flash when it was pitch dark in the garage, so it was a little hard to tell exactly where it was coming from but I've placed an arrow on a pic of the coil where I believe the arcing was occurring. I couldn't see an actual spark or bolt, it was more of a diffuse flash.



I can't see how the tuning would have impacted this, but I only mention it because of the timing and becaue I didn't have an issue before the tuning. I bought the car last fall and haven't checked the condition of the plugs or wires (it has aftermarket wires) so I was planning on swapping out the plugs and wires for new anyway, and I can put a new coil in as well. Is this all necessary and will it fix my problem? Any thoughts on what's occurring? Is the fact that the arcing is at the coil the reason my "misfire" seems to be jumping to different cylinders?

Thanks