Cylinder 1 misfire problem
 

Check engine light is illuminated, I scanned and it's a P301 (cylinder 1 misfire.) I replaced the coil pack rail, new injector and spark plug to no avail. It's still running rough and the CE light is still on. Anything else I need to look at?

I have a 2001 4.0. Thanks!

Read Post #15 in the following link. A buddy of mine fought the misfire codes on his 99, used different fuel additives and the like and only this solved his problem. We're assuming there was a small chunk of carbon umder the exhaust valve.

http://www.wranglerforum.com/f5/does...ork-66616.html