Dreaded Misfire P0300

[Chris Sutphin]

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.




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.



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.

The cylinders in mine are filling with oil. It misfires on 4 of the 6 cylinders. I have no confidence in This gladiator at all. I fear the longevity of this Jeep.

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[ShadowsPapa]

The cylinders in mine are filling with oil. It misfires on 4 of the 6 cylinders. I have no confidence in This gladiator at all. I fear the longevity of this Jeep.

Let's try to define "filling with oil" if we can.............. And who told you "cylinders are filling with oil" ? That's a rather extreme description - and I'd not accept that from any mechanic or tech. It's wild, sounds more like an exaggeration. If they filled, it would hydrolock. It would shoot smoke out the back, there would be errors for the converters, the O2 sensor would be indicating issues - they don't like to be covered with oil.

To reality - which cylinders, and how much oil?
Any proof that it's oil and not unburned fuel? Bad injectors will make things look wet in the cylinder.
Are the techs aware of the PCV system, and where it leads to And how to diagnose or test it?

Back to how much oil - because if the spark plug are WET with oil, you will be dropping oil level in the crankcase an abnormal amount between changes, and would likely notice it out the tail pipe.
I had a V8 that dropped a quart every 800-1000 miles and the spark plugs were not really wet - moist looking, perhaps, on a couple of cylinders, but the rest were not bad looking. My point with that is that if your plugs are wet, drops of oil on them, you'll be going through more than a quart every 1,000 miles - that's a hell of a lot of oil. And you'll see it out the tail pipe. A cat can't handle that much oil, it will plug and malfunction.

Filling suggests there's oil sitting on things - the spark plug comes out with drops of oil on it, not just damp looking.
They need to do compression test, leakdown test, and check the PCV system.

But if a customer came to me, my shop, and said the cylinders are filling with oil - I'd be skeptical, that's a pretty wild term.
I've seen some really bad stuff and that describes an extremely serious problem - I'd want to see it for myself because these days, that just doesn't happen without obvious signs.

 

[MrSauce]

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.

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.

Yes, that was exactly my point. The UConnect vehicle health report is useless.

Yes, I am familiar with how code scanners work. This post is titled P0300, I received that code and was explaining that I also got that code.

Thanks for all the mansplaining! Super-welcoming community you all have here!

 

[ShadowsPapa]

Yes, that was exactly my point. The UConnect vehicle health report is useless.

Yes, I am familiar with how code scanners work. This post is titled P0300, I received that code and was explaining that I also got that code.

Thanks for all the mansplaining! Super-welcoming community you all have here!

You missed the point - in that the uconnect reports aren't even intended for the purposed for which you say they are useless. It's like stating your hammer won't remove the stuck screw - it was not intended for that or that a fishing lure isn't helping you get the fish into the boat.
The reports are a snapshot in time, and the time of the snapshot is dependent on things like connectivity.
So don't complain that the uconnect reports are worthless - they were never intended to be any sort of diagnostic tool.
It's only useless to you - who are expecting it to be something it was never built to be.

You also don't understand dealer shops in this place in time - you were lucky, very lucky, if they only told you 2 weeks. Here, it's 3 to 4 weeks. Some places are worse.
Lemon law - really? Already? Over a misfire? I guess maybe you don't understand how this stuff works.
You have a misfire - no one has been able to get it in instantly to your satisfaction, it's not been diagnosed, you haven't given anyone a chance and you are already looking up lemon law?

Nope, I was right the first time.

 

[MrSauce]

You missed the point - in that the uconnect reports aren't even intended for the purposed for which you say they are useless. It's like stating your hammer won't remove the stuck screw - it was not intended for that or that a fishing lure isn't helping you get the fish into the boat.
The reports are a snapshot in time, and the time of the snapshot is dependent on things like connectivity.
So don't complain that the uconnect reports are worthless - they were never intended to be any sort of diagnostic tool.
It's only useless to you - who are expecting it to be something it was never built to be.

You also don't understand dealer shops in this place in time - you were lucky, very lucky, if they only told you 2 weeks. Here, it's 3 to 4 weeks. Some places are worse.
Lemon law - really? Already? Over a misfire? I guess maybe you don't understand how this stuff works.
You have a misfire - no one has been able to get it in instantly to your satisfaction, it's not been diagnosed, you haven't given anyone a chance and you are already looking up lemon law?

Nope, I was right the first time.

So, you are saying the "Vehicle Health Report" was never meant to be a report of the vehicle's health? Got it. How stupid of me to think it would.

It's gone to the dealership. They can't find the cause. So yes, if the vehicle remains undrivable for a total of 30 days or 4 separate service visits, my state's Lemon Law applies. Why would I keep an undrivable vehicle???

 

[Chris Sutphin]

Let's try to define "filling with oil" if we can.............. And who told you "cylinders are filling with oil" ? That's a rather extreme description - and I'd not accept that from any mechanic or tech. It's wild, sounds more like an exaggeration. If they filled, it would hydrolock. It would shoot smoke out the back, there would be errors for the converters, the O2 sensor would be indicating issues - they don't like to be covered with oil.

To reality - which cylinders, and how much oil?
Any proof that it's oil and not unburned fuel? Bad injectors will make things look wet in the cylinder.
Are the techs aware of the PCV system, and where it leads to And how to diagnose or test it?

Back to how much oil - because if the spark plug are WET with oil, you will be dropping oil level in the crankcase an abnormal amount between changes, and would likely notice it out the tail pipe.
I had a V8 that dropped a quart every 800-1000 miles and the spark plugs were not really wet - moist looking, perhaps, on a couple of cylinders, but the rest were not bad looking. My point with that is that if your plugs are wet, drops of oil on them, you'll be going through more than a quart every 1,000 miles - that's a hell of a lot of oil. And you'll see it out the tail pipe. A cat can't handle that much oil, it will plug and malfunction.

Filling suggests there's oil sitting on things - the spark plug comes out with drops of oil on it, not just damp looking.
They need to do compression test, leakdown test, and check the PCV system.

But if a customer came to me, my shop, and said the cylinders are filling with oil - I'd be skeptical, that's a pretty wild term.
I've seen some really bad stuff and that describes an extremely serious problem - I'd want to see it for myself because these days, that just doesn't happen without obvious signs.

4 of the 6 cylinder are wet from oil. They have had it for 31 days now and still have no answers. Jeep has finally called me but I’m still going in circles

 

[RustySeatbelt]

4 of the 6 cylinder are wet from oil. They have had it for 31 days now and still have no answers. Jeep has finally called me but I’m still going in circles

If it makes you feel any better I'm on 48 days since I dropped it off last month. No idea what they're doing, and I've already had 1 cam replaced.

 

[Gonenuckinfutz]

Sorry to hear guys I guess I'm one of the lucky ones "fingers crossed" they had mine for a week and a half. Inspected the cams everything was fine and they put everything back. I've been driving it since with no issues. About two tanks of fuel so far. And it hasn't acted up again since. Hopefully it stays that way.

 

[GRAYDVLCT]

Bought my Gladiator Last week and driving today the vehicle started stumbling and Stalled/No power... Mil light came on a d flashed a few times shut it off and waited a minute and started back up did the same thing. Called the dealer and told them what. Was going on and they told me to bring it down if possible a d they'll get on it right away.... Needless to say with my vehicle having less than 500 miles this is the last place where I want to be. This does not leave a good feeling in my stomach but ill be level headed until they tell me what happened, why, and what they're going to do to fix this.... I'll keep you updated when I hear something.

 

[ShadowsPapa]

I haven't monitored or logged misfires or other performance items with my truck for a couple of weeks now, but the misfire problems I had at just over 50 miles seem to have self-healed.
No CEL since that very first day, and no shuddering or stuttering of the engine since that second time on that first day, and I have yet to "feel" it being uneven about things.
Maybe the dealer was right - it was that additional 4 gallons of gas or something.
Anyway, I've been running U88 in it since my first fill, I'm at a little over 1,000 miles and no detectable issues.
I'll throw jscan or alfaobd back at it and log some stuff while I take it out for a drive in the next day or two, but unless either of those show a worrisome number of misfires on #2, mine is behaving.

 

[Bobchadwickga]

I've had the P0300 code twice. Both times at startup. The first time the CEL flashed for a very short period of time. Both times the CEL cleared on it's own after a couple of on/off cycles.

I have an appointment next month but unless the CEL is on I suspect the codes will have cleared and they won't find anything.

 

[KWin]

dude complaining about issues with your jeep in this forum is like telling the choir that the pastor is a jerk outside of church. Everyone says he is perfect on Sundays and then bad mouths you to the rest of the congregation.
it's a shit feedback loop that I've noticed after my jeep issues that really killed alot of my jeep stoke. The major and frequent posters are avid defenders of jeep and they are not wrong majority of pentastars are good. but even 1% leaves some of us SOL don't bother arguing you won't get help or sympathy while under warranty

 

[WetWilly]

I've had the P0300 code twice. Both times at startup. The first time the CEL flashed for a very short period of time. Both times the CEL cleared on it's own after a couple of on/off cycles.

I have an appointment next month but unless the CEL is on I suspect the codes will have cleared and they won't find anything.

Exactly the same with mine.

 

[GRAYDVLCT]

Bought my Gladiator Last week and driving today the vehicle started stumbling and Stalled/No power... Mil light came on a d flashed a few times shut it off and waited a minute and started back up did the same thing. Called the dealer and told them what. Was going on and they told me to bring it down if possible a d they'll get on it right away.... Needless to say with my vehicle having less than 500 miles this is the last place where I want to be. This does not leave a good feeling in my stomach but ill be level headed until they tell me what happened, why, and what they're going to do to fix this.... I'll keep you updated when I hear something.

Well they came up with Some Codes but had to get with "Star" to find out what is actually going on and now there is absolutely nothing wrong with my Jeep even though all these codes are stored in memory now and light was on and flashing...

P1D91, P0300, U0002-00, U2500.

They stated I can take it home and will be in contact with me when "Star" Replies back to them. They stated if it happens again to get it back to them asap.

 

[Gonenuckinfutz]

10 months and no issues whatsoever and then all of a sudden today it's back. Seems like once the weather warms up? Normally after I'm pulling my trailer. It's not overloaded at all. But then I'll pull over shut the vehicle down wait a few minutes started up and it's gone. Obviously needs to be a software update. Which they've already tried once

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