New check engine code

jamesrw30

Active Member
Jeep threw a P0304, cylinder 4 misfire. Seems to be running and driving no issue. Cleared it and it came back next drive. My guessing leans more toward coil pack being iffy but wanted to see if that was accurate or should I look more towards plugs?
 

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I'd pull the plug to see the condition, besides the coil, could also be a faulty fuel injector (check the connection) could also be an intake leak.
losing any coolant?
 
Good luck. I just went through this. Is the light intermittent? Or always on? You could try coil pack and or spark plug. I did all that to no avail. Ended up being low compression (mine was cylinder 2). Had to have a new head installed. How there isn’t a class action lawsuit on the heads on these 3.6’s is beyond me. There is a 10 year 150k mile warranty if it’s a 12/13. Mine is a 17 and had 112k miles on it.
 
That's comforting to hear. Mine is a 16 with around 77k but I'm not the original owner. It came on a little while back when I did the thermostat. I cleared it and it stayed off for a while. Came on yesterday, cleared it and it came back next time I drove it yesterday. Stayed on the whole time we were out and about but no issues while driving. Definitely don't think I can swing a new head right now.
 
That's comforting to hear. Mine is a 16 with around 77k but I'm not the original owner. It came on a little while back when I did the thermostat. I cleared it and it stayed off for a while. Came on yesterday, cleared it and it came back next time I drove it yesterday. Stayed on the whole time we were out and about but no issues while driving. Definitely don't think I can swing a new head right now.
Yup. Sounds like mine. Merry Christmas. Was $2300 lol
 
Yup. Sounds like mine. Merry Christmas. Was $2300 lol
🤣 Looks like I'll be riding around with a check engine light for quite a while. Might try the coil pack but there's no chance on dropping that kind of money any time soon. It runs fine so she'll just get chugged along.
 
🤣 Looks like I'll be riding around with a check engine light for quite a while. Might try the coil pack but there's no chance on dropping that kind of money any time soon. It runs fine so she'll just get chugged along.
I'd do a compression test.
 
I'll have to round up a tester but I'm sure I can. I've never done that but watched it done before. Take some studying. But I did stay in a holiday inn express last night.
 
🤣 Looks like I'll be riding around with a check engine light for quite a while. Might try the coil pack but there's no chance on dropping that kind of money any time soon. It runs fine so she'll just get chugged along.
lol yeah my compression was 98 on that cylinder I think. Not too low but low enough.
 
I'll do some research. I really appreciate all your advice. Good to hear from someone who's been through it
 
I had an intermittent cylinder misfire code that turned out to be the ignition coil. The coil had corroded and came apart just enough to interrupt the spark intermittently.

#2 cylinder is located on Bank 2 which the driver’s side. To get to the coil, the upper intake will need to be removed which isn’t difficult if you’re at all mechanically inclined. The biggest challenge is to remove the connectors from the coils without breaking them, if they’re brittle. Find a good YouTube vid showing how to unlock and disconnect them. Use a dab of Never Seize reinstalling the spark plugs and a bit of dielectric grease on the connectors and boots.

I replaced all 6 coils, spark plugs and all gaskets on the intake when I did mine.
 
I had an intermittent cylinder misfire code that turned out to be the ignition coil. The coil had corroded and came apart just enough to interrupt the spark intermittently.

#2 cylinder is located on Bank 2 which the driver’s side. To get to the coil, the upper intake will need to be removed which isn’t difficult if you’re at all mechanically inclined. The biggest challenge is to remove the connectors from the coils without breaking them, if they’re brittle. Find a good YouTube vid showing how to unlock and disconnect them. Use a dab of Never Seize reinstalling the spark plugs and a bit of dielectric grease on the connectors and boots.

I replaced all 6 coils, spark plugs and all gaskets on the intake when I did mine.
Yeah no. Don’t use anti seize on the spark plug. They don’t need it and it is certainly not recommended by the manufacturer. That’s bad advise.
 
From my understanding, using anti seize on plugs changes the torque values. Something like 20%. It is doable if you adjust the torque value accordingly but the manufacturers do not recommend the use of it. I'm guessing to keep people from over tightening due to the decreased value.
 
From my understanding, using anti seize on plugs changes the torque values. Something like 20%. It is doable if you adjust the torque value accordingly but the manufacturers do not recommend the use of it. I'm guessing to keep people from over tightening due to the decreased value.
If the threads break then you can just pull the plug straight out by hand. Or just start the engine and the engine compression can do it for you. 🤣
 
From my understanding, using anti seize on plugs changes the torque values. Something like 20%. It is doable if you adjust the torque value accordingly but the manufacturers do not recommend the use of it. I'm guessing to keep people from over tightening due to the decreased value.
When using anti seize, you should adjust the torque. Does the manufacture say "We don't recommend this" or do they simply not say anything? Do they forbid it?

I must point out I was amiss by not clarifying copper anti seize should be avoided because it can promote dissimilar metal corrosion between aluminum and stainless steel. Don't use copper anti seize on the spark plugs.

Anti seize does provide benefits. It prevents thread galling. This is more important with long thread spark plugs than short thread. It helps the heat transfer from the spark plug to the head so the spark plugs stay within the temperature range better. Anti seize makes spark plug removal easier.

Not much anti seize is needed and don't get it on the electrodes.
 
When using anti seize, you should adjust the torque. Does the manufacture say "We don't recommend this" or do they simply not say anything? Do they forbid it?

I must point out I was amiss by not clarifying copper anti seize should be avoided because it can promote dissimilar metal corrosion between aluminum and stainless steel. Don't use copper anti seize on the spark plugs.

Anti seize does provide benefits. It prevents thread galling. This is more important with long thread spark plugs than short thread. It helps the heat transfer from the spark plug to the head so the spark plugs stay within the temperature range better. Anti seize makes spark plug removal easier.

Not much anti seize is needed and don't get it on the electrodes.
The manufacturer literally say not to use it. A quick Google search will answer your questions. I nobody asked what anti seize does.
 
…nobody asked what anti seize does.
I’m not a “Because I said so” kind of guy. I share my experience, knowledge and opinions so others can make up their own minds. I’m just some dumb jerk on the internet.

With that said, learning has occurred. Turns out several manufacturers apply an anti seize coating to the threads of some of their spark plugs that prevents galling and corrosion, reduces electrical resistance, helps heat transfer and makes it easier to remove the spark plug. The reason they recommended against applying anti seize is to prevent over torquing, particularly in aluminum heads.

Still, some experienced technicians apply a small dab of anti seize because they find the factory coating doesn’t always do a good job of keeping the threads from seizing. As the recommended mileage between spark plug changes is greater than ever, so is the chance of spark plugs getting stuck.

Some experienced technicians don’t apply anti seize and have no trouble at all. I use anti seize because the first time I removed the spark plugs from my Jeep, they were very difficult to remove. I was afraid they’d break.

Bottom Line- If installing spark plugs with the factory coating, an application of anti seize isn’t needed. But as long as anti seize applied sparingly and torque is corrected to compensate, it does have its benefits. The choice is yours.
 
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