My car is throwing a P300 code which is a Multiple Cylinder Misfire. I sprayed the sparkplugs and wires and saw no jump. Jacked the car up and aimed a 35,000 BTU kerosene heater at the optispark thinking it could be moisture in there. Yea, that didnt work, Any suggestions? It starts, and runs, but its like a rough idle.

 

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This can be tricky. A lot of posts have been made about the P0300. Unfortunately, most do not post back when they resolve the issue. My car had it, and I chased it for about a month, until one day the scan tool indicated it was #7 that was misfiring. I could not see anything wrong with the wires, they would not arc that I could see. It was only when I pulled the wire from #7 that I could see a very small black spot on the boot, which was what caused the misfire. An OBDII enhanced scan tool might pick out the cylinder(s) that are misfiring.