Rough when cold.

[SCL79]

I had my 6.4 rebuilt over last winter and got it together in June 2024. New cam and lifters, pistons, bearings etc…. Starting in September when it cooled off I started getting a PO 304 cyl 4 misfire code. It would clear but come back on cold start. Around October you could also hear it detonate a few times on cold start. As it warms up it smooths out until you can’t even feel it run at temp. My mechanic tied switching coils and plugs around as well as injectors and can’t get it to duplicate on other cylinders,stays on 4. Using premium fuel with startron. Have 45 lbs of oil pressure at startup. At a loss.

 

[06 Dodge]

The last time I had a problems rough running was back in 2015, the problem for the old 360 gas engine was a bad O2 sensor

 

[J-13GTP]

I would check the compression on that cylinder. Did the block have anything done to it, was the cylinders checked or bored over?

 

[Burla]

Nevermind I see he did injectors. I still run a cleaner x 2 to clean injectors but still realize this may not solve it. Or get all new ones.

Sounds like a fuel issue.

Not likely with newer pistons but could be dirty chamber, wouldnt hurt to run a cleaner.

 

[SCL79]

Cylinders checked but not bored. I’ll check compression for giggles. I have an interesting device bulletin 18-096 -16 recognizing these codes and recommending an ECU Flash that I’m gonna drop by the dealer and speak with them. I’ll post it so you can read it. Thanks for the replies.

https://static.nhtsa.gov/odi/tsbs/2016/MC-10217742-9999.pdf

 

[SCL79]

So an update. Checked #4 and had low compression, also started seeing smoke. Pulled the engine took back to my rebuilder. Pulled head and had a broken lifter. New push rods and lifters for it and new pan gasket cause it started leaking. Put back in a couple weeks ago and it has started giving me the detonation sneeze at morning startup when cold. Usually barks once or twice and then comes out of it. I’m at a loss. My reader is giving me a code for a small evap leak but that’s it. Once warm it’s smooth as can be. Not liking these 6.4s very much these days.