Dreaded Misfire P0300

[Gonenuckinfutz]

I'm assuming everyone's experience with misfires is different am I right? Well seems like the dealership can't get it to happen to them. Mine seems to only happen after it's been driven for a while everything gets up to temperature park it for a while then go for a drive again and that's when it happens. I keep telling them this but they don't seem to listen. And here I am on a long weekend. Driving a loner because they can't figure it out.

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[ShadowsPapa]

I'm assuming everyone's experience with misfires is different am I right? Well seems like the dealership can't get it to happen to them. Mine seems to only happen after it's been driven for a while everything gets up to temperature park it for a while then go for a drive again and that's when it happens. I keep telling them this but they don't seem to listen. And here I am on a long weekend. Driving a loner because they can't figure it out.

There are some common causes, but we've seen thing like oil leaks on O2 sensors, cams, phasers, and things I am not going to remember right now.
Top of the list is cam/rocker issues, right side, but people shouldn't assume that's it - troubleshooting and diagnosing may prove it's some other cause. But be aware - it exists and isn't something to let go for long.

 

[JeepCares]

I'm assuming everyone's experience with misfires is different am I right? Well seems like the dealership can't get it to happen to them. Mine seems to only happen after it's been driven for a while everything gets up to temperature park it for a while then go for a drive again and that's when it happens. I keep telling them this but they don't seem to listen. And here I am on a long weekend. Driving a loner because they can't figure it out.

We appreciate you sharing your concerns. If you need support while at the dealership, please feel free to send us a private message.

Kate
Jeep Cares

 

[Gonenuckinfutz]

Now the fun begins the dealership can't reproduce the misfire. But the code is always there when I bring it to them. They've been informed by higher ups to inspect the camshafts. Guess I'm not getting it back for a while

 

[Maximus Gladius]

Now the fun begins the dealership can't reproduce the misfire. But the code is always there when I bring it to them. They've been informed by higher ups to inspect the camshafts. Guess I'm not getting it back for a while

I feel your pain . This will pass and one day, you’ll get it back and if they change out the camshaft, it will run like a dream

 

[FLGladiator]

Mine didn't have it but I was notified to come in for an open recall on it. Perhaps you need the update.

 

[RustySeatbelt]

Now the fun begins the dealership can't reproduce the misfire. But the code is always there when I bring it to them. They've been informed by higher ups to inspect the camshafts. Guess I'm not getting it back for a while

I've taken mine in a few times for this, and have already had the cam shaft replaced. Still get the misfire, but now it seems to only happen if I floor it to pass or enter the highway. Over 5500 rpm it happens, and only then. Been at the dealer 21 days today! Do you know the exact condition that triggers yours? I had to walk mine through it step by step since they kept saying they couldn't reproduce it.

 

[Gonenuckinfutz]

I've taken mine in a few times for this, and have already had the cam shaft replaced. Still get the misfire, but now it seems to only happen if I floor it to pass or enter the highway. Over 5500 rpm it happens, and only then. Been at the dealer 21 days today! Do you know the exact condition that triggers yours? I had to walk mine through it step by step since they kept saying they couldn't reproduce it.

Mine started happening once I started pulling my trailer I was loading up firewood bringing it home to split for the winter. So basically once I started making her work a little bit is when it started I wasn't overdoing it I've done the same thing in the past with my JL and my JK I've never had any issues before

 

[Maximus Gladius]

I've taken mine in a few times for this, and have already had the cam shaft replaced. Still get the misfire, but now it seems to only happen if I floor it to pass or enter the highway. Over 5500 rpm it happens, and only then. Been at the dealer 21 days today! Do you know the exact condition that triggers yours? I had to walk mine through it step by step since they kept saying they couldn't reproduce it.

Mine was the same…floor it to get around or pass someone and the truck would blow a cylinder and I’d look behind me to see all the dried mud underneath I could never get off at the car wash, shook off and spread out all over the highway.

 

[Gonenuckinfutz]

Update on my situation... So they took everything apart and didn't find anything out of place with the cams or anything. Everything looked perfectly fine. so now they're putting it back together... Just to see if it will happen again . Frustrating

 

[MrSauce]

This is my first post on this forum because I just got my Gladiator (Overland) less than a month ago. And wouldn't you know it... P0300!

I had the truck for two weeks when the first CEL popped. It was right after I started the truck but it seemed like it was driving fine. I ordered a OBD reader but the light went away before I got the scanner. Then the CEL came back on Friday. This time it was definitely misfiring and running rough. I drove it about 100 yards and it was like somebody was pumping the accelerator. My scanner said it was the P0300. (By the way - that UConnect app is garbage and said everything was green through this whole process.)

To make matters worse, no Jeep dealers had availability for service appointments in the next two weeks!!!! The dealer I bought it from did take it but without an appointment saying they would "work it in" which means it's been sitting on their lot for two days, and the only update was, "we looked at it and see multiple misfire codes, but have no idea what's wrong." I don't think they are able to replicate the issue.

So now I'm googling my state's lemon laws.... our state is 4 service visits or 30 days out of service.

OMG - While I'm typing this, Jeep's UConnect app just popped up a "vehicle health update" notification. All systems still green! SMH. :/

 

[Gonenuckinfutz]

My dealer had my Mojave for over a week and a half put about 300 km on it and almost a half a tank of gas and they couldn't replicate the issue either. They were told to do a tear down and inspect the cams they did that and saw no issue. So now it's been given back to me until it happens again. tried to tell me something about possible bad fuel?? I don't know about that

 

[Chris Sutphin]

I have a 2022 rubicon gladiator and it’s been in the shop for 21 days. Jeep not the dealer is dragging there feet. I had the dreaded p0300 code and the only thing they found was oil in 4 of the 6 cylinders. Star told them to replace the spark plugs which obviously doesn’t cause oil in the cylinders. I wish I would have done some more research before buying the gladiator. I would never had bought one if I knew about this issue which seems like a ton of people are having. It seems like jeep is failing hard with this gladiator issue, it’s obvious that they have no idea how to stop this from happening. I am only a few days away from the lemon law in my state and I am looking forward to getting rid of this pile of bolts.

 

[NachoRuby]

I have a 2022 rubicon gladiator and it’s been in the shop for 21 days. Jeep not the dealer is dragging there feet. I had the dreaded p0300 code and the only thing they found was oil in 4 of the 6 cylinders. Star told them to replace the spark plugs which obviously doesn’t cause oil in the cylinders. I wish I would have done some more research before buying the gladiator. I would never had bought one if I knew about this issue which seems like a ton of people are having. It seems like jeep is failing hard with this gladiator issue, it’s obvious that they have no idea how to stop this from happening. I am only a few days away from the lemon law in my state and I am looking forward to getting rid of this pile of bolts.

Did they replace your valve cover gasket too?

https://www.jeepgladiatorforum.com/forum/threads/dreaded-misfire-p0300.39676/post-644137

 

[ShadowsPapa]

This is my first post on this forum because I just got my Gladiator (Overland) less than a month ago. And wouldn't you know it... P0300!

I had the truck for two weeks when the first CEL popped. It was right after I started the truck but it seemed like it was driving fine. I ordered a OBD reader but the light went away before I got the scanner. Then the CEL came back on Friday. This time it was definitely misfiring and running rough. I drove it about 100 yards and it was like somebody was pumping the accelerator. My scanner said it was the P0300. (By the way - that UConnect app is garbage and said everything was green through this whole process.)

To make matters worse, no Jeep dealers had availability for service appointments in the next two weeks!!!! The dealer I bought it from did take it but without an appointment saying they would "work it in" which means it's been sitting on their lot for two days, and the only update was, "we looked at it and see multiple misfire codes, but have no idea what's wrong." I don't think they are able to replicate the issue.

So now I'm googling my state's lemon laws.... our state is 4 service visits or 30 days out of service.

OMG - While I'm typing this, Jeep's UConnect app just popped up a "vehicle health update" notification. All systems still green! SMH. :/

I guess people don't understand how that report via uconnect works. It's not live, and doesn't monitor every second of every minute. It's not for things like this and is unlikely to report such a thing unless it happens at the time the report is being gathered.
The uconnect report is not live on the spot so of course it's likely "green" while you read a code.

I would never had bought one if I knew about this issue which seems like a ton of people are having. It seems like jeep is failing hard with this gladiator issue, it’s obvious that they have no idea how to stop this from happening.

It looks worse because you are here where people talk of troubles. It's like looking in a hospital to see how healthy the human race is.
As far a "no idea how to stop this from happening........." if you have followed this for a long time you'd see that there isn't necessarily a common cause for all misfires. People seem to believe gee, 10 people have a misfire code! What is THE fix as if there is a single cause and a single fix for each. If there are 10 people who experience this, there are likely at least 4 or 5 different causes.
Misfires can be cause by any number of things - including bad O2 sensors, cams, plugs, coils, as well as other things I won't list.
My wife had a misfire code with her Jeep - it ended up being spark plugs. It's been fine for over a year and 6,000 miles since. They aren't all the same.
Saying Jeep doesn't know how to stop this from happening is like saying Goodyear hasn't figured out how to stop everyone from having a flat tire. You are assuming every misfire has the same source and that's simply not true. Granted, there are "common causes", but looking at the history, even among forum members, the fix hasn't been the same for every one of them.

My scanner said it was the P0300.

Basic code scanners are all but worthless for any diagnosis. You knew it was a misfire without a code reader, and the P0300 is a generic multiple cylinder misfire. It says nothing about the reasoning behind it.
It needs to be caught in the act - with a logger, catching freeze frames, looking at the status of everything going on at the time.
A good diagnosis will tell if it's ignition, fuel, or other, more than a generic P0300 multiple cylinder misfire.

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