2011 Durango w/3.6L, misfire counter shows misfire on cyl. 1, 3, & 5. At start up it runs fine, shortly after it runs very rough.

 

What steps have you taken thus far to troubleshoot?

 

I've monitored the misfire counter and also watched the O2 voltages. Seems like 1/1 isn't switching all the time. Actually only when throttle is applied. Also the exhaust smells of sulfur and at idle an tone will come on and the CEL will then blink, after a bit it repeats and goes solid. I can't seem to find a correct firing order for this engine. I doubt my scan tool would switch the banks but it seems like the symptoms of the 2-4-6 cyl misfire head replacement issue.

 

Flip the O2 sensors and see if the problem follows.

 

After poking around some more I noticed there was oil on the 1/1 sensor. I've tracked it down to the PCV leaking at the rear of the passenger side valve cover. I've resealed that (major PITA) and will install a new O2 today. Also a PITA, they only wanted tiny hands Rob Lowe working back there.

 

Well the O2 was bad. A new one has cleared up all the issues. The PCV leak was likely the culprit.

 

Good find, and thank you for the follow-up on what it took to repair.

-Rod