p0304 rough idle. | Ford Explorer Forums - Serious Explorations

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p0304 rough idle.


Well-Known Member
November 29, 2012
Reaction score
City, State
columbus ohio
Year, Model & Trim Level
2006, 4x4 Limited 4.6
Car was running fine, pulled into my driveway and shut it down. Started the car again about 20 minutes later and it was idling pretty rough, also rough on acceleration. Check engine light came on about 3 minutes down the road and it gave a p0304 code when I got home.

Coil pack is my first guess. However, the truck does have an exhaust leak and I have noticed it idles a bit rough on startup and as the leak tightens up with the heat the engine would run smoother. So I am curious if perhaps that could cause this issue? Would the engine throw a misfire code if the issue was the O2 sensor getting a faulty reading?


Why suspect the coil, and not the plug?

Swap the coil, and see if the code moves to the swapped cylinder.

I actually just went and got a coil and swapped it out. it seems to have fixed the issue.