Cylinder 8 misfire

Hi everyone, When I first start up, cylinder #8 misfires within the first 1000 revolutions. In the past, when I changed the spark plug, the issue would disappear for a few months. I would change the plug when the light came on again, and for a few months, there were no check engine lights. The issue does not follow the coil after I swapped the coils. I can get rid of the light for now, but it will return in a few days.

The code numbers are P0300, P0308, and P0316.

Any Ideas?


Based on the codes and your description, it seems like a persistent issue with cylinder #8.

The misfire could be due to a variety of factors, such as a faulty ignition system, fuel system issue, or even an internal engine problem.

Given the intermittent nature, I would recommend checking the spark plug and coil again, ensuring they’re properly torqued and free from damage or corrosion.

If the issue persists, consider inspecting the fuel injector and checking for vacuum leaks.

A professional diagnostic may be necessary to pinpoint the exact cause.


There seems to be an issue with the fuel system. The continuous misfiring of the spark occurs at any engine speed. Misfires related to fuel can seemingly stop at higher speeds due to the fuel being diverted from the other intake runners.

Also, I’d do a compression test first. If compression’s good, then it could be the fuel injector or wiring issue. If it’s bad, you might need to take off the cylinder head.