P050D & P0303

[Chukbacca]

Hi all-
2015 1500 crew cab tradesman 3.6l

In June, with about 97k miles I was prepping for a road trip and the day before departure I got two codes P050d (cold start rough idle) and p0303 (cylinder 3 misfire). Not wanting to deal with it during a road trip, I replaced all of the plugs and the coil pack with the hope that it would just resolve everything with limited investigation.

For the bulk of the trip, I ran seafoam with every tank and no codes seemed to pop up.

Upon returning home, I started seeing one or both codes intermittently. The truck now has north of 111k miles and both codes are coming up more consistently.

I am familiar with the Pentstar tick as I replaced the rockers in a previous minivan. I do not hear a tick. I also do not feel a misfire. When I previously pulled the spark plugs, I was pretty fascinated that the plugs all looked alike (number three did not look any different than the others)

Has anyone else experienced an official cold start rough idle? Does anyone have any thoughts as to what I might explore?

Thanks as always for your time

 

[SitKneelBend]

Hi all-
2015 1500 crew cab tradesman 3.6l

In June, with about 97k miles I was prepping for a road trip and the day before departure I got two codes P050d (cold start rough idle) and p0303 (cylinder 3 misfire). Not wanting to deal with it during a road trip, I replaced all of the plugs and the coil pack with the hope that it would just resolve everything with limited investigation.

For the bulk of the trip, I ran seafoam with every tank and no codes seemed to pop up.

Upon returning home, I started seeing one or both codes intermittently. The truck now has north of 111k miles and both codes are coming up more consistently.

I am familiar with the Pentstar tick as I replaced the rockers in a previous minivan. I do not hear a tick. I also do not feel a misfire. When I previously pulled the spark plugs, I was pretty fascinated that the plugs all looked alike (number three did not look any different than the others)

Has anyone else experienced an official cold start rough idle? Does anyone have any thoughts as to what I might explore?

Thanks as always for your time

When I had a rough idle at start it was the fuel injector failing.

 

[Chukbacca]

Oh yeah - I forgot to mention that I replaced the injector a few months ago - thanks for the thought!

 

[SitKneelBend]

Oh yeah - I forgot to mention that I replaced the injector a few months ago - thanks for the thought!

So I also had a second injector on the same bank go a few months later. Dealer said they wanted to replace the last one on that bank too but the warranty wouldn't cover it. 2 and 4 were replaced, 6 is still holding out a few years later. If you have a multimeter I can share the tech's notes with you to test the injector too.