Survey- For those with misfire issues

[ShadowsPapa]

If so, what has been done to try to solve the issue? Nothing yet other than to check/seat all relays/fuses in fuse block.

That's not going to help with that code.
It's telling you exactly what was wrong - the coil for that cylinder was malfunctioning.
The solution would normally be replace that coil - fuses should have no impact in a single cylinder misfire, let alone a secondary circuit malfunction. It's going to take a dealer visit if it happens again.

In short, you have a unique problem, ignition coil for #3 cylinder. Fuses and relays won't fix that.
The injectors and coils are all under fuse F70.

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[GrubbyBaja]

That's not going to help with that code.

Yes, understand the fuse issue. That was a reference to the previous instance before I had the exact codes. Question: are the codes stored? Will the dealer be able to pull those codes since the MIL never stays on?

 

[ShadowsPapa]

Yes, understand the fuse issue. That was a reference to the previous instance before I had the exact codes. Question: are the codes stored? Will the dealer be able to pull those codes since the MIL never stays on?

I've not found anything solid on that. Some appear to clear after a certain number of miles, some say after a certain number of successful key cycles.

Our Grand Cherokee bucked like a bronc with a burr under the saddle - #3 ignition misfire. The MIL never came on and a code was never stored. It eventually went away while driving it to the dealer - no code was found.
Luckily I had recorded the sessions and had a log of the events and conditions at the time and they used that to track the issue - well, they never directly tracked it because it only misfired one time for them - one single misfire, and never triggered a light, never stored a code. I had proof of the problem - pages of proof, so they persisted and found a TSB that suggested the issue was spark plugs. They replaced the plugs and it's been fine since.

It appears the code being stored is a thing dependent on several factors - and if the issue no longer exists, it appears to be cleared after certain time periods.

 

[Hootbro]

Build date: 10/2019 Rubicon, 6MT, stock.
Mileage when it first occurred: 23,500
How many times has it occurred: This was the 3rd time. 1st time @ ~12,000 miles; 2nd time @ 19,500 miles.
What exact codes did it throw: Had my OBD reader in the console, pulled it out and plugged it in while engine was still running and check engine light was flashing. 2 codes: P0303, Cylinder 3 misfire and P2308, Ignition Coil 'C' Secondary Circuit.
Is the issue on going? Unknown
If so, what has been done to try to solve the issue? Nothing yet other than to check/seat all relays/fuses in fuse block.
Was the issue ever fully resolved? Unknown
Description of misfire: Driving along a SE Alabama 2-lane highway (minor hills to level) at approximately 55 mph, 5th gear, with cruise control set. Outside air temp ~80F, oil temp ~190F, coolant temp ~194F, voltage ~14.3, all of which are normal readings for my vehicle. Cruise control deactivated, ASS light illuminated, and a notable misfire was noticed as soon as I gave it throttle to maintain speed. 3-5 seconds after noticing the misfire, the yellow check engine light began flashing. Maintained 55 mph in 5th gear with a continuous misfire (felt like loss of a single cylinder as the vibration was a constant frequency). Pulled out my OBD reader and plugged it in and read codes (while maintaining 55 mph). After approximately 2 minutes, with vehicle still misfiring and check engine light flashing, pulled off road and shut down vehicle. Restarted vehicle and everything was normal. Both previous instances were identical except I kept driving and the misfire stopped after 2-3 minutes, check engine light stopped flashing and check engine light remained off.

More than likely bad #3 coil. You are lucky in that it is on the passenger side bank and not under the intake like the drivers side. I would swap #1 and #3 coil and see if it travels and call the coil if it does. If not, looking at wiring or signal drive issue with the PCM.

 

[P0300!]

New to this forum as I just got a new 2022 Overland and have the P0300 error and misfires.

Build date: No idea, it's at the shop. Will update later.
Mileage when it first occurred: ~500 miles
How many times has it occurred: Many, but very intermittent
What exact codes did it throw: P0300
Is the issue on going? Yes, but it is very random and hard to reproduce
If so, what has been done to try to solve the issue? The first time it was at the dealer for a week and they couldn't reproduce it so they cleared the codes and sent it home. After about a week at home it started again. Its back at the dealer now, but they haven't been able to reproduce the misfire yet. They are leaving the OBD scanner on it and going to try a bunch of cycles to see if they can capture it in the actual misfire condition.
Was the issue ever fully resolved? Nope!
Description of misfire:

Very intermittent misfires, but it's always and only right after startup, like right after the Uconnect screen clears its warning/info. When it misfires you can tell. It definitely shakes and runs rough and throws the flashing CEL. If I immediately pull over and shutoff the truck, wait a couple seconds, and restart, the engine purrs fine and even the CEL is gone. Occasionally, it doesn't clear the CEL and it will stay on solid for a few days and then eventually clear itself. Only other thing I notice, is it's very hot here and it seemed like it would do it more often when the AC was cranked up, that could be a coincidence though. I didn't experiment with that theory much though, I just took it back to the dealer service dept.

I'll keep all posted. Thanks for this forum!

 

[ShadowsPapa]

AC can make even a smooth engine feel rougher - the compressor, the belt, etc. gives things a rough feel especially at idle before it goes into closed loop mode, and right after start up as it goes into idle is where even normal engines often see a misfire - but those are small or few in number and go away in seconds, and don't trigger any light of any sort, nor store any DTC.

Can you record the issues yourself? I did with a Bluetooth OBD adapter and software on my phone with my wife's 2021 Grand Cherokee. Caught it in the act and logged it. I printed the log for the dealer - it was behaving fine when I got it to them.

 

[ShadowsPapa]

Joined the club today. But mine is very different.
Cold start - fine. Shut it off for just a few minutes (like 5 or so) and start it - it's fine.
Drive it until hot - fully warmed up, go into a store or church or whatever for 20-45 minutes, come back out, it starts fine and runs fine for about 2-3 minutes and then goes into ding ding ding mode with blinking CEL.
First tine the CEL flashed several times and then locked on.
Second time - tonight - it flashed on and off a lot of times, dinged several times, then I pulled over to set my phone up to log misfires and it was bucking and running REALLY rough - one or two cylinders were not firing AT ALL. I'd say at least one cylinder was dead.
Then as I sat there and got the phone to log - it smoothed out and ran GREAT the rest of the way home!
The good - the bad cylinders were on the left bank.
One cylinder had 0 misfires from the second half of the trip home, another had 1 single misfire.

This is caught in the middle of it bucking badly - the numbers popped up as soon as my phone connected as if it gathered stored info from the truck -
The minimums are where things were when it first connected - of course it settled down and smoothed out as quick as I got the phone hooked up to log!

This was after we stopped 5 minutes for ice cream - maybe 10 miles home this time around...

It's almost as if it's temperature related.
Cold start - it's fine. Drive 10-15 miles, it's fine.
Stop, shut down, leave it for 20-45 minutes, start it - it's fine.
2 minutes after the hot start - it kicks DTCs.

2022/07/16 10:13:13.333
Faults found.
P0300
___________________________
2022/07/16 10:13:19.251
Faults found.
P0300
___________________________
'Clear fault codes' command sent
___________________________
'Clear fault codes' command sent
___________________________

 

[NachoRuby]

Sorry to hear. I'm taking another trip to FL tomorrow (600+ miles) Last trip had a flashing CEL that went off after a few minutes. Never ran bad and haven't had an issue since we got home last week. Wouldn't the Wranglers have the same issues since they're using the same engine? I hope they can fix what's causing yours.

Yep, Wranglers are identical from the b-pillar up. They have the same everything, side from springs and shocks. Same issues.

 

[ShadowsPapa]

Yep, Wranglers are identical from the b-pillar up. They have the same everything, side from springs and shocks. Same issues.

I'd imagine the tunes would need to be different - and tow modes on the trucks, stuff like that. Engine hardware the same, programming different.

 

[Hootbro]

Joined the club today. But mine is very different.
Cold start - fine. Shut it off for just a few minutes (like 5 or so) and start it - it's fine.
Drive it until hot - fully warmed up, go into a store or church or whatever for 20-45 minutes, come back out, it starts fine and runs fine for about 2-3 minutes and then goes into ding ding ding mode with blinking CEL.
First tine the CEL flashed several times and then locked on.
Second time - tonight - it flashed on and off a lot of times, dinged several times, then I pulled over to set my phone up to log misfires and it was bucking and running REALLY rough - one or two cylinders were not firing AT ALL. I'd say at least one cylinder was dead.
Then as I sat there and got the phone to log - it smoothed out and ran GREAT the rest of the way home!
The good - the bad cylinders were on the left bank.
One cylinder had 0 misfires from the second half of the trip home, another had 1 single misfire.

This is caught in the middle of it bucking badly - the numbers popped up as soon as my phone connected as if it gathered stored info from the truck -
The minimums are where things were when it first connected - of course it settled down and smoothed out as quick as I got the phone hooked up to log!

This was after we stopped 5 minutes for ice cream - maybe 10 miles home this time around...

It's almost as if it's temperature related.
Cold start - it's fine. Drive 10-15 miles, it's fine.
Stop, shut down, leave it for 20-45 minutes, start it - it's fine.
2 minutes after the hot start - it kicks DTCs.

2022/07/16 10:13:13.333
Faults found.
P0300
___________________________
2022/07/16 10:13:19.251
Faults found.
P0300
___________________________
'Clear fault codes' command sent
___________________________
'Clear fault codes' command sent
___________________________

Is this on the new 2022 JT you ordered?

 

[ShadowsPapa]

Is this on the new 2022 JT you ordered?

Yes. It was perfect on Thursday, perfect on a trip to Ames and back (a strong 50 minutes each way with 3 stops while up there) and then with about 150 miles on it today - started the misfires.
But only under certain conditions, and pretty much left bank.

I've not got JSCAN licensed for this new one yet
and AlfaOBD doesn't like my modules although it works, it's spewing stuff that doesn't really make sense.
It was so rough tonight on the way home from church that for a while my wife was worried but I told her it was mostly 1 cylinder from the feel of it - and JSCAN supported that with the misfire counts. Once going again, it was fine and ESS worked.
So it's a very different situation than what most are seeing.

 

[Snook]

Joined the club today. But mine is very different.
Cold start - fine. Shut it off for just a few minutes (like 5 or so) and start it - it's fine.
Drive it until hot - fully warmed up, go into a store or church or whatever for 20-45 minutes, come back out, it starts fine and runs fine for about 2-3 minutes and then goes into ding ding ding mode with blinking CEL.
First tine the CEL flashed several times and then locked on.
Second time - tonight - it flashed on and off a lot of times, dinged several times, then I pulled over to set my phone up to log misfires and it was bucking and running REALLY rough - one or two cylinders were not firing AT ALL. I'd say at least one cylinder was dead.
Then as I sat there and got the phone to log - it smoothed out and ran GREAT the rest of the way home!
The good - the bad cylinders were on the left bank.
One cylinder had 0 misfires from the second half of the trip home, another had 1 single misfire.

This is caught in the middle of it bucking badly - the numbers popped up as soon as my phone connected as if it gathered stored info from the truck -
The minimums are where things were when it first connected - of course it settled down and smoothed out as quick as I got the phone hooked up to log!

This was after we stopped 5 minutes for ice cream - maybe 10 miles home this time around...

It's almost as if it's temperature related.
Cold start - it's fine. Drive 10-15 miles, it's fine.
Stop, shut down, leave it for 20-45 minutes, start it - it's fine.
2 minutes after the hot start - it kicks DTCs.

2022/07/16 10:13:13.333
Faults found.
P0300
___________________________
2022/07/16 10:13:19.251
Faults found.
P0300
___________________________
'Clear fault codes' command sent
___________________________
'Clear fault codes' command sent
___________________________

when I got my flashing CEL last month it was after driving around town for awhile, it was hot outside and the engine was hot. Started flashing and dinging right after we started up after one of our stops. Never ran rough though. CEL flashed and went off after a few minutes. On the next start up it came on and stayed on until we got to a dealership. They cleared the code and haven’t had one since (that was 1200 miles ago)

 

[P0300!]

AC can make even a smooth engine feel rougher - the compressor, the belt, etc. gives things a rough feel especially at idle before it goes into closed loop mode, and right after start up as it goes into idle is where even normal engines often see a misfire - but those are small or few in number and go away in seconds, and don't trigger any light of any sort, nor store any DTC.

Can you record the issues yourself? I did with a Bluetooth OBD adapter and software on my phone with my wife's 2021 Grand Cherokee. Caught it in the act and logged it. I printed the log for the dealer - it was behaving fine when I got it to them.

That's a good idea. It's still at the dealership now, and they said they were going to leave their reader in while they try to reproduce it. When I get it back, I plan on just leaving a logger hooked up. I hope this is just an easy software flash to fix it.

 

[P0300!]

Just an update on mine...

I heard from the service department and they started tearing down the engine and found alot of metal shavings. They don't know where they're coming from or what's causing them yet. They are going to reach out to Jeep to see what they should do... keep digging or replace the engine.

Not a very good start to Jeep ownership.

 

[ShadowsPapa]

Just an update on mine...

I heard from the service department and they started tearing down the engine and found alot of metal shavings. They don't know where they're coming from or what's causing them yet. They are going to reach out to Jeep to see what they should do... keep digging or replace the engine.

Not a very good start to Jeep ownership.

Ouch.
Apparently not cams or they'd have seen that damage right on top. First thing, IMO, would have been take off valve covers........ and go from there.
If they have found "shavings" one could wonder - what have they gotten into......


I got a call from a tech at the dealership I bought mine from. He asked if I wanted to bring mine in and they'd work it on as soon as possible and check it over. I suggested we hold off as when we were out and about today, it was working well, no CEL, no dinging, and only the typical misfires you'd see (although I have a feeling it's a bit on the high side.
I'll drive it as much as possible in the next couple of days and see how it does. I'm recording things as much as I can. JSCAN chokes on my tablet every time I try to log everything in the PCM.

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