Cylinder 2 Misfire / P0302 on a 2007 JK

JeepinLife

Caught the Bug
man oil on the plug isn't good. Run the compression check. As for the exhaust if its blue thats also oil, if white it means you have water leaking.. either could be from a cracked head. Or bad rings.
 

j3ph3ry_j33p

New member
do you, by chance , change your own oil ( as you should) and per-chance did - during a change- happen to overflow or spill any amount of the 5w20 / 5w30 down the side when filling and maybe get a collection of it within that cylinder plug receptacle that could have , in turn, been enough to get sucked back into the cylinder when the cracked or loose plug was causing the misfire? This is more common than you think and causes much mis diagnosis of more severe troubles......i'd clean that port out with throttle body cleaner or seafoam spray and then ensure a tight,new plug was properly installed and see what goes down .
 

LoPo

Caught the Bug
Thanks. Oil was changed back in July.(I work from home so I no longer put huge DD mileage on it.)

I have a date to take it into a mechanic next Thursday but I plan on swapping the Coil and plug wires before taking it in.

Anyone know which coil is better? Or if the more expensive one is better?

http://m.oreillyauto.com/mt/www.ore...835_3975&keyword=coil+pack&pt=C2377&ppt=C0334

http://m.oreillyauto.com/mt/www.ore...835_3975&keyword=coil+pack&pt=C2377&ppt=C0334



Sent from my SM-N900V using WAYALIFE mobile app
 

LoPo

Caught the Bug
I returned last night from being out of town for 10 days and finally got to get back looking at this. I had a coil and a wire kit on my doorstep waiting or me.

First thing I was going to try was swapping the cable out, so I grab the kit that Amazon said "fits your vehicle". Unfortunately it did not. 4 wires?

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So I decided I would look at the new plug I installed the night before I left....I drove 6 miles on it earlier today. Freakin dirty..oh and it broke too.
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Not feeling lucky today I decided to put the OEM plug back in.. After a bit of cussing I decided to swap the coil...thinking when this doesn't change the behavior I still need to test the cable. Anyways, swapped the coil and it fired up sounding and smelling normal. Took it around the block and it felt fine.

Few hours later I ran to get some food for the family and I noticed I had a slightly rough idle while at stop lights. Not sure what that's about, but it gave the jeep a slight shake and I noticed a tiny / negligible dip on the tach. I was thinking that I should be a clean plug back but not sure what else to check.
 

Sharkey

Word Ninja
Damn LoPo...sucks to try and chase down motor gremlins. I'm a dumbass when it comes to motor issues and end up having to rely on a shop. Hopefully you can get this worked out soon.
 

txjeeplover

Member
I had been experiencing a mild misfire for a few days which got worse yesterday, and then I got the P0302 code after revving the engine just like you. I swapped out the coil pack and I noticed improvement, but it was still off. Next, I replaced all of the plugs and wires and it went away completely. I drove several miles over country back roads, the interstate, and several minutes idling in a drive-through after leaving a NYE party and it never returned.

I noticed that all of plugs were slightly out of gap and that there was chaffing between the wires for cylinder 4 and 6, but none of the plugs were damaged.

As best I can tell from my frantic research of various forums yesterday, the P0302 code means a misfire on cylinder 2, and the best solution to cure the problem on the 3.8 is a complete tune-up, while on the 3.6 the solution is a new head. That of course varies from Jeep to Jeep, but that's the pattern that I learned.
 

LoPo

Caught the Bug
I had been experiencing a mild misfire for a few days which got worse yesterday, and then I got the P0302 code after revving the engine just like you. I swapped out the coil pack and I noticed improvement, but it was still off. Next, I replaced all of the plugs and wires and it went away completely. I drove several miles over country back roads, the interstate, and several minutes idling in a drive-through after leaving a NYE party and it never returned.

I noticed that all of plugs were slightly out of gap and that there was chaffing between the wires for cylinder 4 and 6, but none of the plugs were damaged.

As best I can tell from my frantic research of various forums yesterday, the P0302 code means a misfire on cylinder 2, and the best solution to cure the problem on the 3.8 is a complete tune-up, while on the 3.6 the solution is a new head. That of course varies from Jeep to Jeep, but that's the pattern that I learned.

Hrm ok, that's good to know. I will look at sourcing the correct wire kit and perform a full plug replacement. Any advice on how to get to the plugs on the passenger side? It looks super tight in there and I have large hands. :blush:
 

LoPo

Caught the Bug
Damn LoPo...sucks to try and chase down motor gremlins. I'm a dumbass when it comes to motor issues and end up having to rely on a shop. Hopefully you can get this worked out soon.

Thanks. Yea, I have minimal patience for this stuff. Trying to remain calm and hopefully learn some thing from doing as much troubleshooting myself before dropping it off to a shop.
 

Hack12

New member
I had the same symptoms you are having last year with my '08 JKU while I was driving in a Target parking lot. Very rough idle, intense shaking and little to no throttle response. Eventually I pulled a P0304 (cylinder 4 misfire).

Long story short, I changed the spark plugs and wires and have never had another issue again.
 
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txjeeplover

Member
Hrm ok, that's good to know. I will look at sourcing the correct wire kit and perform a full plug replacement. Any advice on how to get to the plugs on the passenger side? It looks super tight in there and I have large hands. :blush:

For the passenger side plugs, I disconnected the breather hose going to the air box to get additional room. Next, I used the spark plug socket with a very short extension (1" I think) and I allowed the wrench to hang down low. You only need the wrench to break the plugs loose. You should be able to remove the plugs with the socket and short extension by hand after you loosen them with the wrench. For installation, VERIFY YOUR PLUG GAPS, and then hand thread the plugs in by hand. The plugs should thread to base with relative ease and only require 1/4 turn or so with the wrench for proper torque. Oh and be sure to apply dielectric grease to the plugs and coil pack before installing the wireset. It makes removal of the plug wires next time sooo much easier. The first time I removed the factory wires, I broke 3 or 4 of the connectors because they had fused to the plugs.
 

LoPo

Caught the Bug
I ordered the wire kit and it arrived last night. I spent the afternoon today swapping the wires and plugs. Looks like that did the trick, it seemed to be idling smoothly and I drove it around the block testing various rpm ranges where I'd get a misfire or stutter before, didn't find any. I want to put some more mileage on it before I call it solved, but it's looking like it. :thumb:

I followed Jeepfan's write-up for the swap...http://wayalife.com/showthread.php?7347-Jeep-JK-2007-2011-Spark-Plugs-and-Ignition-Wires-Write-Up :clap2:

I will say changing these out isn't a easy/simple task. The wire routing is a pain as is getting to the plugs in cylinder 1 and 3. You also definitely want a flex head socket wrench. I didn't draw blood, but I may have scrapped my arm and smacked hands a number of times. I'm sure the neighbors enjoyed the profanity. :D
 

txjeeplover

Member
Congrats!!! I'm glad that it worked out for you, and I also felt a great deal of relief when my misfire disappeared and the idle was smooth. For me, that two hours of cursing and cuts was worth it to have my Jeep driving like new again and eliminate the check engine light.

BTW, you may want to consider changing your ignition coil pack too. It's relatively inexpensive compared to other late model vehicles, easy to access, and easy to replace. Better to replace it on your terms, rather than having it go out on you later at an inconvenient moment.
 

LoPo

Caught the Bug
Congrats!!! I'm glad that it worked out for you, and I also felt a great deal of relief when my misfire disappeared and the idle was smooth. For me, that two hours of cursing and cuts was worth it to have my Jeep driving like new again and eliminate the check engine light.

BTW, you may want to consider changing your ignition coil pack too. It's relatively inexpensive compared to other late model vehicles, easy to access, and easy to replace. Better to replace it on your terms, rather than having it go out on you later at an inconvenient moment.

Thanks. I swapped the coil on NYE. That cleared the check engine light. The wire kit and plugs appear to have solved the rough idle and stutter..
 

Wallerdog

New member
Same problem

I am working through the same issue on my 07. I started it up (warm engine) and it was ROUGH running. Had the codes checked & it's cylinder 2 misfire. I added seafoam, no change. I suspect that I haven't run enough through the engine to give it a fair chance to work.
I changed out the spark plug, no change. The OEM plug was remarkably clean. I confirmed that the plug is getting electricity using the "screwdriver" method.
What is the next most easiest/cheapest step to try?
 

rabbihoward

New member
same problem 07' sport

i had the same symptoms on my 07 wrangler and after replacing spark plugs, wiring, and the ignition coil the problem is gone
 
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