I'm getting code 306 cylinder#2 missfiring on my 2001 jeep Cherokee. I swap injectors plugs but still get the same code.

 

Well first of all a P0306 is cylinder 6 misfire.
And sometimes a misfire code is just a misfire code.
Had a P0304 once. Turned out to just be the spark plug.

 

Yes, it was a 302 not a 306. I swap spark igniters with #1 cylinder and the code switched to #1, so the spark igniter was the issue. Had a spare so the issue is solved. Took it for a half hour drive and all seems well.

 

You posted an update right as I was posting this. Looks like you have solved it.
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*For the 00-01 (with coil rail) I'd first try a new spark plug, properly gapped to .035.

*After that, I'd swap fuel injectors. I think with you saying in your original post "I swapped injector plugs", that means you already swapped both the fuel injector and the spark plug?

*Next up is determining if you have a pulse going TO the fuel injector from the computer. A simple "noid light" will tell you that.

*Don't forget about the possibility of something internal going on. Run a compression test on all cylinders. Spec for the 4.0 liter engine is 120-150 psi with no more than a 30 psi variation between cylinders.

*Still in the mix would be coil rail (but they often fails two cylinders at the same time when going south), and of course all wiring specific to that cylinder, like fuel injector wiring.

Good luck and keep us updated!

 

Thanks for you response. As I replied to Ralph77, the issue turned out to be a bad spark plug. I removed #2 spark and it was soaked with fuel, so I then removed the #1 spark plug and swapped it with #2. This time, when I ran the engine, I got a PO301 or Cylinder 1 Misfire Detected. I had a spare spark plug so I replaced the bad one and all is working just fine. I'll be replacing all spark plugs tomorrow just to make sure, but right now everything is aok.