Code PO300, multiple misfires

Hi,

It seems you know what to check for. Do you feel the misfire when driving? Is the engine running okay or does it seem to have a loss of power?

There are a lot of things that can cause a random misfire. A partially clogged catalytic converter, leaking fuel injector, low engine compression and so on.

Take a look through this link and let me know if anything helps:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Take a look through this link and let me know if this is how you checked for vacuum leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you have a live data scan tool, check the short term fuel trims and let me know what you find. Also, if you have noticed a power loss, you can try removing the O2 sensor before the catalytic converter to see if it makes a difference as far as power. Here is a link that explains the symptoms of a converter issue:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know also if you checked engine compression. Low compression can create a misfire as well.

Take care and let me know.

Joe