P0301 and Auto Start/Stop

[gouacats]

I assume these aren't related, but they both started at the same time...

- 2020 Mojave with ~93000 miles.
- Just returned from a 400 mi tow on Monday (~3500 lb Travel Trailer)
- Noticed the Auto Start/Stop wasn't charging during the trip back
- Tuesday - Got the Auto Start/Stop error, then it went away, then it came back
- Also Tuesday - When it came back the 2nd time, the check engine light also came on (P0301, Cylinder 1 misfire)

Again, I assume unrelated, but wanted to check with the brain trust. Any thoughts?

Edit - It doesn't seem to drive any differently...I'm not noticing a misfire.

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[Lost1wing]

Any enging code will prevent ESS from working.

Fix the misfire!

 

[ShadowsPapa]

Any enging code will prevent ESS from working.

Fix the misfire!

Mine said ready - until I came to a stop then said it wasn't ready. Once the misfire MIL went away after a restart or two, it worked fine again. But it was a transient misfire - weird circumstances (easily fixed later)

 

[gouacats]

These make sense. I could feel the misfire for the first 10 seconds or so after starting it this morning. It's now sitting at the dealership waiting for them to have a chance to look at it. They said maybe next week. Anyhow, luckily, I have my old JK to drive around for the time being.

 

[Lost1wing]

Must be logic waiting for a gate to be triggered. If you restarted and the fault was still there, maybe it wouldn't have said ready. If you restart and the fault was gone then I can see it saying ready.

Mil and ESS ready at the same time ? Random misfire p0300 that cleared itself?

 

[ShadowsPapa]

Must be logic waiting for a gate to be triggered. If you restarted and the fault was still there, maybe it wouldn't have said ready. If you restart and the fault was gone then I can see it saying ready.

Mil and ESS ready at the same time ? Random misfire p0300 that cleared itself?

Freaky, eh? Yeah. It cleared. It started at that mileage - 2 days after getting it.
It would set the MIL, then after stopping at another store and restarting, the MiL was gone and ESS worked fine.
That was the hot-restart issue. It was fine on cold starts, only happened after thoroughly warmed up, shut off, then restarted about 20-40 minutes later. A misfire that was either so mild you could hardly tell, or so wiled it bucked like a bronco with a burr under the saddle, then it came out of it. Sometimes the MIL was set, sometimes it wasn't set.
CCDIFF was never "learned". Dealer forced a relearn of CCDIFF and the issue went away completely. Then a few days later, a TSB came out about it.
Mine was one where Jeep's STAR team requested detailed information about the issue.
It's had no misfires, no codes, no MIL since. ESS has worked perfectly - at least according to that chart I've posted a few times as to what criteria must be met.

 

[gouacats]

Update since people hate to hear about issues without any resolution. They are replacing the engine. I have a question into them to figure out what they actually found. Obviously more than just needing a new head gasket. They didn't authorize new spark plugs, so I have to pay for those.

I'm assuming the auto stop/start will resolve itself with the new engine, but have that question into the dealer as well.

 

[gouacats]

Last update unless something goes wrong:

Picked up the Jeep with new engine (new engine, 3 year/100k warranty). So far so good...doesn't appear to be any leaks and it seems quieter. That being said, I've been driving my old JK around for a month, which is definitely NOT quiet, so it is probably just my imagination! The issue was coolant leaking into the cylinder through the cylinder wall. The auto start/stop issue was cleared up with the new engine, so confirmed they were related. Now to get my fancy shocks rebuilt and it will be like driving a new Mojave.

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