Intermittent cylinder 4 misfire

Fistlaw

New Member
Joined
Jan 18, 2025
Messages
7
Location
Texas
What to do next?
Replaced plugs, coils and upgraded the injectors. The light goes on, I clear it with a JScan…a week and ~200miles later it’s back.
Runs super smooth but I’m perplexed what next?
Pix for attention…
IMG_8264.jpeg


IMG_8266.jpeg
 
Yes, OEM
I’m not familiar with the ECM reset process.

 
I recommend examining the wire harness at/around cylinder #4.
If you feel ambitious, consider swapping the plug and coil pack from #4 w/ another and see if the misfire remains on #4.

I would also consider doing a compression/leakdown test.
Although rare, I recently read a post stating that their misfire was the result of a crack in the head.
 
  • Like
Reactions: Fistlaw
Well, it’s been a while but thought I’d follow up.
Cyl 4 has a valve that won’t close all the way so it’s not holding compression.
So after some serious emotion annd strings of four letter words coupled with disbelief, I’m going to pay a few grand to have it fixed. I’m all in and a new motor is too expensive, and a few grand isn’t even 6 months of car payments so…
I’m just shocked really. I bought her used with 70k-ish miles and don’t rag on it. I’m the second owner, but I’m absolutely shocked that an engine would lose a valve with only 93k miles.
 
@Fistlaw Appreciate the update. 🙏 Very sorry to hear. Certainly beats buying another used Jeep that'll come with surely its own 'issues'. And new— I personally cannot stand the push button start and dual battery setup.