Cylinder No. 4 Misfire

[k99jk99j]

That was kinda where I was going with that earlier post, PS, but then it decided to start increasing the noise with RPMs. I'll know more after the compression test (or maybe I won't). We'll see.

i take the offending valve cover off also. you might only have a rocker arm that has popped loose? mike

 

[ThunderbirdJunkie]

Stupid question
Did you swap coils with the #4 cylinder? Didn't see it mentioned. A randomly firing coil can cause the smell and part of the buildup you described.

 

[ShadowedXistence]

The valve cover is easy to do... and as long as the gasket is still good, you can reuse it... and if it's not good, than atleast you were able to replace it ; )...

you haven't mentioned anything about overheating and such... also, have you checked the oil, and does it look milky... it doesn't sound like a cracked head or leaky head gasket...

 

[MickityMike]

Stupid question
Did you swap coils with the #4 cylinder? Didn't see it mentioned. A randomly firing coil can cause the smell and part of the buildup you described.

Yeah, I swapped coils 1 and 4 before I even registered an account here.

But thanks!

i take the offending valve cover off also. you might only have a rocker arm that has popped loose? mike

Yeah, that's on me list, too. A another friend of mine worked for Chrysler for 15 years (until recently... something about them never making money...) and he claims that the spring is kind of notorious in the 3.7L.

you haven't mentioned anything about overheating and such... also, have you checked the oil, and does it look milky... it doesn't sound like a cracked head or leaky head gasket...

To my knowledge it's never been overheated... but I'm also the second owner, so who knows? Oil is dirty as hell (it's a little overdue for a change) but not overly thin, not milky, not nothing out of the ordinary.

When I was in the parts store the other day talking about all these symptoms to the dbags behind the counter, a guy in line who claimed to be a mechanic said that it sounded to him like it could be a cracked head or bad gasket. He was saying that normally you'd get some fouling in at least 2 cylinders, but weirder things have happened.

I don't know, I'm still not convinced it's something that severe though. Either way, this is turning into kind of a mystery.

 

[ShadowedXistence]

the springs breaking were more notorious for the older models than they were for the newer models... still not uncommon... a bad coil should strike a code... It has to be something to do with the valve train... the rocker for the timing chain could be loose or broken, and the sound you are hearing could be a loose timing chain slapping against the rocker... so make sure you check the tension on the chain when you remove that valve cover...

 

[ThunderbirdJunkie]

Bad coil doesn't always throw a code.

 

[ShadowedXistence]

a bad coil should strike a code...

I understand not everything is perfect though TBJ

 

[MickityMike]

Bad coil doesn't always throw a code.

In a perfect world, the computer would say, "Good morning, Mike. You've got a broken valve spring on no. 4. ...What are you doing, Mike? This is highly unusual... Don't attempt to shut me down, Mike."

So what does Cap'n T-Bird think the problem most likely is? Does he have an (helpful) opinion?

 

[ThunderbirdJunkie]

First thing to do would be swap the #4 coil with a known bad one. It won't make the P0304 go away, but another code should pop up if the coil is the problem.
Could also pull the coil, and see if it affects how the Jeep runs.

This is all very free and very low effort, rather than pulling the head to take a gander at what's all up in dere

 

[MickityMike]

First thing to do would be swap the #4 coil with a known bad one. It won't make the P0304 go away, but another code should pop up if the coil is the problem.

Hmm, forgive my ignorance, but I'm not sure what this'll tell me? If I've already swapped out coils 1 and 4 and the misfire remains at 4, wouldn't that still tell me that the coil isn't the problem, that it most likely has something to do with cyl. #4?

Could also pull the coil, and see if it affects how the Jeep runs.

Okie doke, no coil at all on #4. So... What will a change in the Jeep running tell us (me)?

This is all very free and very low effort, rather than pulling the head to take a gander at what's all up in dere

I do appreciate things that are free and low effort. That's my kinda style.

Do you have any idea at all what the popping sound could be? My assumption is, now, that it's probably something in the valve train - is that assumption mistaken? Could it be something else all together? (Well, I suppose it could, but is it likely?)

I've counted pops while in idle, and presently they're at every 2 to 8 seconds. No less than 2, no more than 8.

Would a Ouija board be helpful? Maybe the Jeep wants some sort of rooster sacrifice?

 

[ThunderbirdJunkie]

pops at idle...could be unburned fuel igniting in the exhaust system...could be valvetrain...depends on your definition of popping and where it's coming from

 

[MickityMike]

pops at idle...could be unburned fuel igniting in the exhaust system...could be valvetrain...depends on your definition of popping and where it's coming from

True. This is part of the problem trying to describe engine sounds over the 'net.

Well, it does sound like a minature backfire and it's coming right from the heart of the ol' engine. Like right smack daberoo in the center.

Oh well. Either way I appreciate your attempts to help.

 

[MickityMike]

Anybody know where I can get a live rooster from?

 

[ThunderbirdJunkie]

Actually, yes...

 

[MickityMike]

Alright, now we're talking! How is the rooster with small objects? Like a hammer or a blade?

 

[ThunderbirdJunkie]

He's quite handy. He's trained in Tae Kwon Do and ballet, also

 

[Warren.fischbeck]

He's quite handy. He's trained in Tae Kwon Do and ballet, also

Your the one that stole creamsomeyounguy... I should have known.

 

[ShadowedXistence]

you can feel that vibration over the intake manifold can't you... and btw my problem.. ALSO on cylinder 4... very very similiar to yours... and it was a bad lifter... mine was an 04... hmmm

 

[MickityMike]

Know what really ***** right now? There's a slight chance we might get significant snow in 24 hours... MUST FIX JEEP NOW!

 

[ShadowedXistence]

You can open it up and check it out in a day... order the part... wait 2 days for it, and put it back together in a few hours... probably looking at 4-5 days... ONLY because you'll have to wait for whatever parts you'll need... *****!