Started misfire cylinder three

Hi and thanks for using 2CarPros.

There are many things that can cause a misfire. Things such as fuel pressure, timing, engine compression engine vacuum leak can all contribute to the problem. First, switch the cylinder two coil with cylinder one. See if the misfire changes cylinders.

Now, you replaced the sensors. I am going to assume they did that because there were o2 sensor readings that were out of spec. I noted that you indicated you are a beginner mechanic, If you have access to a live data scanner, I need you to tell me the fuel trims when the vehicle is running. Also, you should check fuel pump pressure and confirm compression.

Based on the readings you give me (fuel trims) I will have a better idea of what may be causing the misfire. As far as the wiring harness, if they are bad, they are bad, in other words, cylinder three won't fix itself and the problem move to cylinder two.

I don't know if you need them, but here are links that discuss the things I suggested testing:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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

https://www.2carpros.com/articles/how-to-test-engine-compression

The attached picture provides fuel pressure specifications.

Let me know what you find or if you have other questions.

Take care,
Joe