Misfire code - where to go from here?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

yippee

Full Access Member
Joined
Jun 23, 2015
Messages
82
Reaction score
0
Location
Texas
Okay, I'm back with another misfire code. I'm needing to get some ideas on where to go from here to get this stinkin' thing figured out once and for all.

Little history for you. Back in June of '16 I was having some misfire issues. At that time I was having a p0300 "random/multiple cylinder misfire" and a p0303 "cylinder 3 misfire". Swapped cylinder 3 coil pack to another cylinder, and the code did not follow.

I was planning on putting new plugs in it anyways, and there were a few non-Mopar coils on it so I went ahead and bought two. I put NGK copper 'OEM' spark plugs in it, gapped per the sticker under the hood. I replaced the non-Mopar coils with Mopar coils because I assumed they would be a problem at some point and I was already there anyways - so why not?

Got all of that done, cleared the CELs. Started driving it, went ahead and got it inspected while the light was out, after multiple driving cycles. Once it was legal I started driving it daily, and haven't really had much of a problem since - been happy with it since then.

Fast forward to a couple of days ago. I noticed a few times (I'm not sure if this has anything to do with the problem or not, but I'm throwing it out there in case it does and helps in diagnosis) when I would go to start the Jeep it would start, but immediately stumble and die. It would start but act like it didn't have everything needed to run. This only happened a few times, but seemed to be after I had driven it, parked, shut it off, then come back to get in it to leave. So mostly up to temp, parked, then started before fully cool. Again, not sure if that has anything to do with anything, but I want all the details out there.

Fast forward a few more days to today. I had been driving it around running errands pretty much all day. Went to go eat dinner with some family. Came back out to get in it and head over to their house. Jeep started right up but was running rough again, kind of looked down at the gauges and it instantly threw a CEL. After running it seemed to have evened out some, but the CEL was still on. Drove to their house and went in for a while. Came back out, after initial startup it idled rough again. Seemed to smooth out once it ran again. (Note: When I say smoothed out, I mean in comparison to the initial startup and idle. I'm not saying it did or didn't go away. It just had a very lopey idle initially and I didn't notice it in that degree after it ran a minute).

After all the festivities I came back home, plugged in the OBD scanner. It's showing p0300 "random/multiple misfires detected". Great.. No designated cylinder, just a random misfire code. So I have no cylinder to focus on, just a misfire that I want to solve. So here I am, before you, hoping for some help diagnosing this misfire. From doing a lot of reading I know everyone says coils and spark plugs (done and done). Then that seems to always be followed by crank sensor and cam sensor. Is this my next step? Looked online, look to be about $30 each for Mopar. Doesn't seem too bad.

I just want to know what steps I should take next. I just want to get this thing figured out and fixed. All help is appreciated.
 

ltd02

Comfortably numb
KJ Supporting Member
Joined
Aug 15, 2014
Messages
2,695
Reaction score
238
Location
North Central Maryland
Be a good idea to try to get some live data on a scanner and see what all the sensors etc are doing.
 

Logan Savage

Full Access Member
Joined
Aug 14, 2015
Messages
245
Reaction score
0
Location
WV
Pull your spark plugs & see if they all appear the same on the end with the electrode .
 

yippee

Full Access Member
Joined
Jun 23, 2015
Messages
82
Reaction score
0
Location
Texas
Thank you all for the help, replies, and ideas.

Hoosier - I wasn't sure if the stumbling had anything to do with it or not, but I wanted to have all the details out there in case it was in some way related as it might have led to a more conclusive answer. I have read that as part of my reading on the subject. Seems to suggest as follows:

Coils (check)
Plugs (check (see later))
Cam sensor
Crank sensor
O2 Sensor
Fuel rail
And eventually to a debate about fuel, lol

I have replaced the spark plugs and a couple of the non-OEM coils. That was kind of the comprehensive list I had compiled in my efforts of reading up. Those are the things I'm looking at doing next. I just wanted to check with someone who knew these motors better than I to see what the next steps I should take are.

ltd - I can hook my scanner up again and see what all it shows. I don't know what all data it displays, so I'm not sure if that will be helpful or not. I can see if that shows anything that might be helpful.

Logan - I can pull my plugs again and check them to see if they look abnormal or not. I'll probably mess with that on Sunday or Monday when I have more time to deal with it.

Are these the correct parts that I need?
More Information for MOPAR 56044180AC
More Information for MOPAR 56041584AF
 

LibertyTC

Well-Known Member
Staff member
Moderator
Joined
Oct 24, 2008
Messages
9,081
Reaction score
1,747
Location
B.C. Canada
I would also want to clean the IAC and associated port.
Spark plugs should be replaced as per under hood sticker and all 6 of them at once gapped correctly.
New spark plugs every 30k miles or sooner. Jeep likes new plugs!
You do have 6 new spark plugs right?
What did the old plugs look like? /pics even better.
Coil packs- OEM Mopar are best, and I would generally recommend 6 of those at once.
Not a lot of sense using the parts cannon.
A good shop scanner can show all the good live data, especially great when it is misbehaving.
58298[/ATTACH]"]
You must be registered for see images attach

In the pic a Snap On Modis Ulta is being used.
 

Attachments

  • Jeep%20OBD%20Scan4.jpg
    Jeep%20OBD%20Scan4.jpg
    102.6 KB · Views: 0

yippee

Full Access Member
Joined
Jun 23, 2015
Messages
82
Reaction score
0
Location
Texas
Sorry for the delay folks, ended up getting busy with life - you know how it goes.

Luckily as my dad taught me growing up, I kept the old spark plugs and marked on each box which cylinder they came out of. Hopefully the picture is okay. If not I can try to get another picture in the daylight tomorrow, assuming it isn't too overcast. Take a look and let me know what you think:

You must be registered for see images attach


Those are the old plugs, notice they were Iridiums. I did replace all 6 at once. On the coils I only replaced 2 instead of 6. When I played the coconut shell game trying to diagnose the misfire the misfire did not follow the coils, therefore I didn't assume the coils were to blame. I really just replaced the 2 because they weren't OEM and I was ordering some other parts at the same time. Perhaps I need to replace all of the coils again, at the same time.

I don't think my scanner has any of that function on there - mine's not as big and fancy as that. As of right now the CEL is back off (it came on, stayed on, went out briefly, came back on briefly, and then went back out and has been out so far (knock on wood)), so I haven't really been able to scan it and get any more info yet.

So far this is kind of my running list of things to look at/clean/replace:

Coils
Plugs
Cam sensor
Crank sensor
O2 Sensor
Fuel rail
IAC and port

Are the cam and crank sensor in the links at the bottom of my last post the correct ones? So I can go ahead and get those ordered. '05 Liberty Limited. 3.7 Auto. If that makes any difference.
 
Last edited:

justjeeps

Member
Joined
Jan 30, 2017
Messages
76
Reaction score
1
Location
canada
number 2 looks like it was loose for some time and allowed moisture / water in - hence the rust on the threads..
 

J33Pfan

Full Access Member
Joined
Jul 28, 2016
Messages
411
Reaction score
15
Location
NY
number 2 looks like it was loose for some time and allowed moisture / water in - hence the rust on the threads..

#2 also looks like a bad O-Ring on the coil -its letting fluids reach the spark plug tip.
Either change the O-RIng or Coil for a new one. But definitely a Big Problem there!
 

tommudd

Moderator
Staff member
Moderator
Joined
Jul 14, 2005
Messages
22,456
Reaction score
3,642
Location
Southeastern Ohio
How many miles since the new plugs?
Would be interesting to see what the number 2 plug looks like now
Also coils break down over time, should replace like spark plugs, all at once.
Which cylinders did the new coils go on?
 

yippee

Full Access Member
Joined
Jun 23, 2015
Messages
82
Reaction score
0
Location
Texas
Uss - Sorry, I accidentally put an '07 instead of '05 (my truck is an '07, so it slipped out). The Jeep is indeed an '05 and I have updated the previous post in order to avoid any further confusion. Sorry again about that.

Justjeeps and J33P - I did notice the signs of fluids on cylinder 2. I installed everything myself this time (it had been done by somebody by the previous owner the last time), and I made sure everything was snugged up well this time. I will be going back to check everything again to make sure fluid isn't getting into the hole anymore. Cylinder 2 was one of the ones that got a new coil, so hopefully that helped resolve the issue there.

Tom - Honestly, I messed up and didn't write down the exact mileage when I changed the plugs, so I just had to estimate. I do know it can't have been more than 2,000 miles and honestly it's probably at least half of that. I will definitely pull the plugs again and take a look at them and snap a picture and report back. I just figured I would start with a picture of the old plugs since I still had them on hand. We have like a weeks worth of days in a row with rain chances, so it may be a little bit before I have a chance to tackle that. I'll definitely get them out and report back as soon as possible. Good to know about the coils. This is my first vehicle with coils. I should have known that, but I didn't think about it like that for some reason. I'll get 6 new ones added to the order when I order the cam and coil sensors. I'll have to look again on the new coils, I forget exactly which cylinders they ended up on. So how often should the coils be replaced? Just for future reference.

Other than the fluid on #2, do the spark plugs otherwise look okay?
 

yippee

Full Access Member
Joined
Jun 23, 2015
Messages
82
Reaction score
0
Location
Texas
Would be interesting to see what the number 2 plug looks like now

I know it's been a while, but here is what #2 plug looks like now, after they were replaced (earlier picture).

You must be registered for see images attach


Also installed the Cam Sensor earlier today and will be replacing the Crank Sensor soon. Hopefully I can get all of this misfire nonsense behind me.
 

sch

New Member
Joined
Apr 4, 2018
Messages
4
Reaction score
0
Location
Texas
I am dealing with the same issue as well.
I've done the plugs and coils, and just threw a p0300 today.
I'd love to hear if and how you got it fixed!
 

Latest posts

Members online

Top