Thanks for your reply,

I'll need to double check their work I didn't do a thorough ground inspection on the left bank area.

While removing the valve cover I found the braided strap that ran from the hood/body to engine rusted off at the engine. I replaced it after installing the rockers. I also cleaned the ground strap at the pcm. There was a noticeable improvement with misfires on daily driving, I assumed the improvement was the new rockers, its possible it could have been the new ground strap. I recall doing a voltage drop test awhile ago. I will inspect all grounds and do another voltage drop test.

Would anyone have a schematic of the ground system?

The only thing I question about a ground issue is that it would typically have misfires on both banks not just one.

 

I was told my pcm was flashed before they installed the left head. The dealership had some missteps while installing the head, the tech forgot to torque the cross over bolts which led to a coolant leak when I got it home. I thought it best to double check their work and confirm the flash was competed.

I talked to the service manger and he said he couldn't tell me if they did a flash before installing the head or not there wasn't anything in his files that said he did. However, he said he had his best tech doing the job and if it needed it he would have done it. I reminded him that same tech let a Jeep go out the door without finishing his job.

Later he showed me a screen indicating my Jeep didn't need the update (no lighting bolts). This turned out to be false.

He asked me to come back the next day and he would plug me in to see if I had any updates.

The following day after plugging in they found a update the service manger said had absolutely nothing to do with misfires, but if I wanted to get the update he would charge me $145 (he said it was a light switch update, again nothing to do with misfires).
I wasn't buying it.

At the end he let me talk to his best tech to see if he had any ideas about my misfire problem, which now has an engine light on while daily driving.

The tech was generous with his time but after explaining everything I've done he had nothing to add. Simply saying he had no idea what it could be. I then talked about updates so he walked me over to where my jeep was hook to a computer and opened the page. He seemed surprised to see a flash for misfires, he also added that he highly doubts the flash would help my misfires because of the miles on the engine saying those flashes only help with newer engine with less miles.




With this new info I went back to the manger and let him know that in fact the update was associated with misfires. He then said he would do the update for $145. I told him the tech highly doubted the update would work. I told him I would be happy to pay him if the flash fixed my misfires but wouldn't just hand over the cash if it didn't. He wasn't going along with it so I told him I'll revisit this at a later date which gives me time to figure my options.
It was my thought they would routinely flash the pcm before installing a new head, I told the manger this and he said there is nothing that requires him to do it. General practice comes to mine. I spent over 2 hours at the dealership I would have thought they would have just updated it knowing the misfires I've had after their left head installed.

Today I cleaned all the grounds and checked for voltage drop and found none. A bad grounds it not the problem.

 

Hard to believe they don't want a happy customer especially since it started after they worked on your jeep. I think these are TSBs so if you under warranty it should be covered (maybe also under the warranty of the work you had done especially since it started then. Also, f you can find anything that states the update has to be done due to the work you had done you can argue it needs and there is no written evidence that you did the update. This is tough since you really don't know if the update will fix it or not.

 

I'm out of warranty
I contacted jeepcares, they said get it done, and they would reimburse me.
It will be somewhat of a surprise if they do what they say.
I'll wait to see if what I did last Sunday stopped the misfires.
If the misfires come back I'll have the pcm flashed.

 

TBS 18-007-12 from my photo above.
https://f01.justanswer.com/dodgetech...9dd0_P0300.pdf

 

After bypassing the service manger I talked to the general manger and he was willing to work with me and flashed the pcm today at no charge. I'll keep you update on the results.

 

I had the pcm flashed on 11/19/19 and for 12 days the engine ran great just a few single digit misfires which isn't a problem.

Yesterday I had a cylinder 1 misfire pending. This morning I put the trans in reverse and I could feel the misfires and the engine light came on indicating a cylinder 1 misfire.

I can clear the codes and it will do the same thing, run good for awhile, then eventually the misfires come back.

 

Damn sorry to hear you're still dealing with this issue.

 

Thanks,

A day after the engine light came on its running good again. I found 7 misfires each on cylinder 1,3,and 5 not enough to make it run bad. The engine light is still on yet its running good. When the engine light comes on I typically find 30-50 misfires.

I'm not getting any misfires on the new left head. The dealership tech told me I tried everything he would do.

If I gave the jeep to the dealership to repair they would just replace the head (this is what they told me).

The right head has passed my compression and leakdown test. Before replacing the left head it passed a compression test and failed a leakdown test.

Unless someone has a better idea I believe the problem is carbon buildup. I had temporarily good results from intake cleaning so I'm going to give it another go of cleaning while the engine light is on to see if the cleaning makes the light go out.

 

Update,

I've been working on this issue since the end of last springs. I've done everything any other mechanical would have done. The dealership techs, and other mechanics I've talked to say they would replace the head even though it has good compression and passed a leakdown test.

I solved my problem with this engine last night.....I traded the Jeep in for a 2020 Chevy Silverado. Thanks to those who contributed to this thread it is much appreciated.