Engine misfire codes P0352 and P0302

[MattFogel]

Hello, everyone!

I am a little stumped on whats wrong with my jeep. Some advice before i start replacing parts would be appreciated.

So i have a 2004 TJ 4.0 inline six with 159k miles. I took the jeep on a dirt road a month ago and when i was completely done and maybe 2 miles from getting home I felt the engine start misfiring.

I checked the code when i got home and it read a p0352. so i found online that it was probably the coil pack or spark plugs. it made sense to me because i have had the jeep for 2 years and havent replaced either yet. (I dont think the previous owner did either.) So i replaced the coil pack with REPJ504607 from carparts.com and for the plugs i used were Autolite XP985 Iridium XP Spark Plug from amazon. I checked the gaping on the spark plugs per specs used dielectric grease in the boots.

The jeep sounded much better after this. and I didnt notice for a couple weeks any misfire or engine codes. I was only driving to work in back 15 miles on I70 back and forth. but i was driving through town and it started with the misfire again. I checked the code and this time it showed P0302 and P0352. I cant confirm that P0302 was showing before I did the Coil pack and plug swap. the weird thing is I can only get the engine to start misfiring by driving over one of our town's raised brick crosswalks. (it doesn't happen every time either.) I have messed around with all the wiring going into the injectors and the coil pack its self and it wont start misfiring. another interesting thing is when the misfire is happening I can just stop the car and start it again and there is no problem. the misfiring stops and wont start back unless I drive aggressively over one of these cross walks. the misfire has yet to start while driving on smooth road or highway.

I put some Lucas injector cleaner in my gas tank and used about half the tank and it hasn't seemed to fix the problem. been trying to not drive her till i figure this out. let me know what you guys think. I could use some help.

 

[Jerry Bransford]

Does the misfiring seem to only start when the engine is hot or it's a hot day?

 

[MattFogel]

Does the misfiring seem to only start when the engine is hot or it's a hot day?

I guess if I had to pick when it starts misfiring its on the cold side. But I have a sneaking suspicion that it would do it at full temp too.

 

[Jerry Bransford]

I guess if I had to pick when it starts misfiring its on the cold side. But I have a sneaking suspicion that it would do it at full temp too.

As opposed to being "on the cold side" does that mean it would misfire as soon as the engine is started first thing in the morning? Or does it have to warm up at least mid-way before it starts misfiring?

 

[MattFogel]

As opposed to being "on the cold side" does that mean it would misfire as soon as the engine is started first thing in the morning? Or does it have to warm up at least mid-way before it starts misfiring?

it has not misfired once when i first start it up. only after a few mins of driving. As i said before too, if I turn it off and start it back up it wont be misfiring. Also it wont misfire every drive. Only about one in every three drives.

But It hasnt started misfiring at full temps. At least not that I have seen yet.

 

[Jerry Bransford]

I'm a little confused then... no misfiring when the engine is cold in the morning, it misfires only 1 in 3 drives while it starts to warm up a little, then stops misfiring once fully warmed up? Do I have that right? If I do, I have no clue what could cause that set of symptoms.

 

[mots]

If you are getting the P0352 "Ignition Coil B Primary/Secondary Circuit Malfunction", then it is telling you where to look.

First, check the ignition coil engine harness connector first (behind the coilpack assembly on back passenger side of engine bay near the firewall). Unplug, inspect, and clean the coilpack connector with electrical parts cleaner. Make sure it is making a good connection. Check the wiring harness side of the coilpack and trace it back where you can to see if anything looks odd or damaged.

If it's not the connector or wiring, then it's possible it could be a bad coilpack, but start with the the spark plugs first. Particularly look at the spark plug on cylinder 2 since you get the P0302 (Cylinder 2 misfire detected) with the P0352. If you have 154k, swap them for new OEM if they haven't been done in ages. I would try the spark plugs first since the coil packs are more expensive, and since only cylinder 2 seems to be affected. The coilpack assembly has 3 integrated ignition coils and they each provide spark for two cylinders. If one of those were bad, I'd suspect a misfire in cylinder 1 as well, not just cylinder 2 (I believe the first coilpack unit to the front of the Jeep services cylinders 1 and 2).

Hope this makes sense. Good luck!

Potential causes of P0352:
from: https://www.yourmechanic.com/articl...econdary-circuit-malfunction-by-blake-griffin

• Damaged or corroded wiring of the coil pack
• Damage or corrosion of the wires connecting the coil pack to the Engine Control Module
• Open or short in the wiring of the electrical circuit of the coil pack
• Faulty Engine Control Module
• Faulty coil pack
• Defective Spark plug(s)

 

[MattFogel]

I'm a little confused then... no misfiring when the engine is cold in the morning, it misfires only 1 in 3 drives while it starts to warm up a little, then stops misfiring once fully warmed up? Do I have that right? If I do, I have no clue what could cause that set of symptoms.

so whenever the misfire starts the engine is not full temp, around the 150 mark. so the engine hasnt been completely cold either. so after i have been monitoring it this past week. the misfire hasn't happened at full temp either. so there does seem to be a correlation with a cold engine. but as i said before there has not been a startup misfire yet. meaning i can start up and the engine will get full temp and wont misfire once.

and what i mean by the "misfire every 1 and 3 drives" is that the misfire doesnt happen every drive. only when i make short drives around town.

does that make sense?

 

[MattFogel]

If you are getting the P0352 "Ignition Coil B Primary/Secondary Circuit Malfunction", then it is telling you where to look.

First, check the ignition coil engine harness connector first (behind the coilpack assembly on back passenger side of engine bay near the firewall). Unplug, inspect, and clean the coilpack connector with electrical parts cleaner. Make sure it is making a good connection. Check the wiring harness side of the coilpack and trace it back where you can to see if anything looks odd or damaged.

If it's not the connector or wiring, then it's possible it could be a bad coilpack, but start with the the spark plugs first. Particularly look at the spark plug on cylinder 2 since you get the P0302 (Cylinder 2 misfire detected) with the P0352. If you have 154k, swap them for new OEM if they haven't been done in ages. I would try the spark plugs first since the coil packs are more expensive, and since only cylinder 2 seems to be affected. The coilpack assembly has 3 integrated ignition coils and they each provide spark for two cylinders. If one of those were bad, I'd suspect a misfire in cylinder 1 as well, not just cylinder 2 (I believe the first coilpack unit to the front of the Jeep services cylinders 1 and 2).

Hope this makes sense. Good luck!

Potential causes of P0352:
from: https://www.yourmechanic.com/articl...econdary-circuit-malfunction-by-blake-griffin

• Damaged or corroded wiring of the coil pack
• Damage or corrosion of the wires connecting the coil pack to the Engine Control Module
• Open or short in the wiring of the electrical circuit of the coil pack
• Faulty Engine Control Module
• Faulty coil pack
• Defective Spark plug(s)

i just replaced the coil pack and the spark plugs. but i will take a look at the harness and wires. and then i will take out the plug to take a look at it.

 

[jjoiner7399]

i just replaced the coil pack and the spark plugs. but i will take a look at the harness and wires. and then i will take out the plug to take a look at it.

Did you ever figure out the issue. Mine is doing the same thing