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Discussion Starter #1
2004 Jeep Rubicon, 20k miles, automatic

I don't drive my Jeep much, and it has sat for almost 3 weeks waiting on a new driveshaft that finally showed up this week.

I drove it around Thursday night and out of nowhere it ran rough for about 30 seconds and the CEL blinked, then it cleared up and seemed to run fine. Got home and pulled a P0303 code (cylinder 3 misfire).

Drove it today and out of nowhere the same thing happened, except this time it was worse and at one point the Jeep stumbled badly. CEL blinked then stayed on solid. I got home and pulled P0301 and P0303. The engine also had a noticeable tick to it when I got in the garage that cleared up after I turned it off and restarted.

After searching the forum all I can conclude I'm either out a set of spark plugs, expensive cats, or will soon need a new engine (the "Death of a 4.0" lifter thread below this one has me scared to death!!!).

The Jeep has always ran well enough, although it has always seemed to idle somewhat rough in the year I've owned it. But I also am under the impression the old 4.0 is not as smooth as a new Cadillac either.

I'm off to buy some new NGK spark plugs. What else should I be doing?

Thanks
 

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Jeepless in PA
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Re: Jeep throwing misfire codes, need some help

Your spark plugs are fouled so a simple change to ngk or champion 4412 and you should be fine.
 

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Re: Jeep throwing misfire codes, need some help

...and disconnect the battery for 20 minutes to clear the codes out of the computer. I had the same problem, but the code did not come back. Hope the spark plugs solve your problem.

You have even lower mileage than my 2005. My dealer recently chewed my butt for letting mine sit for long periods of time. It causes a bunch of problems.
 

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Discussion Starter #5
Re: Jeep throwing misfire codes, need some help

Ok new NGK plugs are in. The ones I put in happened to be the exact ones I took out, so I don't know if they were the stock plugs or had been changed before. They all looked almost exactly the same, no real differences, with a gray color to them. I checked the gap on them and most had opened up to around .045. I set the new ones to .035.

I started it up and it seemed to run a little smoother than before, however I still think something is going on with either a valvetrain noise or exhaust noise. I have somewhat of a "baseball card in bicycle spokes" noise when it's driving. The real weird thing is that coming down a big hill I could let off the gas and let the motor idle and the noise went away. I also had some sort of a stumble/shake at 1900rpm that was really weird but definitely noticeable.

I stuck my head under the hood and revved the motor and the valvetrain clacking got a lot louder, however I'd never done that before and figured it was just the sound of it speeding up.

The Jeep didn't throw any codes during my 5 mile test drive, so should I just turn up the radio or keep investigating?
 

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Jeepless in PA
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Re: Jeep throwing misfire codes, need some help

cdogg44 said:
exhaust noise. I have somewhat of a "baseball card in bicycle spokes" noise when it's driving. The real weird thing is that coming down a big hill I could let off the gas and let the motor idle and the noise went away.

I would take a look at the exhaust manifold's bolts since they are known to become loose along with any possible holes in the exhaust pipe.



cdogg44 said:
I also had some sort of a stumble/shake at 1900rpm that was really weird but definitely noticeable.
I also had that happen a few times after I installed new plugs. I gather that the computer is still adapting to the change.

cdogg44 said:
I stuck my head under the hood and revved the motor and the valvetrain clacking got a lot louder, however I'd never done that before and figured it was just the sound of it speeding up.

The Jeep didn't throw any codes during my 5 mile test drive, so should I just turn up the radio or keep investigating?

Clacking is coming from where? what side of engine? by the tranny? at the tranny?
 

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Discussion Starter #7
Re: Jeep throwing misfire codes, need some help

I will check the manifold bolts.

Makes sense to me on the stumble. I wound it out a little after that and it ran great so who knows.

With my head under the hood opening the throttle body by hand it sounded like the noise was under the valve cover towards the very front. But keep in mind, !. I've never listened like this before and 2. I was pretty much trying to hear valvetrain noise, so it's probably all in my head.

I don't know what it is lately but with all these failure threads around here I've been paranoid about my motor screwing up or my transmission going out. Of course with the luck I've had lately both will happen tomorrow.
 

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Re: Jeep throwing misfire codes, need some help

cdogg44 said:
I will check the manifold bolts.

Makes sense to me on the stumble. I wound it out a little after that and it ran great so who knows.

With my head under the hood opening the throttle body by hand it sounded like the noise was under the valve cover towards the very front. But keep in mind, !. I've never listened like this before and 2. I was pretty much trying to hear valvetrain noise, so it's probably all in my head.

I don't know what it is lately but with all these failure threads around here I've been paranoid about my motor screwing up or my transmission going out. Of course with the luck I've had lately both will happen tomorrow.
I tried to tighten the exhaust manifold bolts...but that is easier said than done. I did notice I would wiggle the exhaust quite a bit and was able to get some of the bolts on the small cats to tighten up.

Went for another drive on the same loop I took earlier and the Jeep started off running great. I tried to replicate the 1900rpm shake and was able to in the exact spot, but then thought it was a 39mph driveline vibration as I have just installed a new CV driveshaft. The spot on the road where this happens was when the Jeep shifts into 3rd, running about 1900rpm, and then the road begins to climb a decently steep hill. Jeep shook and stumbled badly. Drove it around and up it a second time...this time it did the exact same thing and the CEL started to flash. It ran HORRIBLE and I was barely able to climb the hill...got it stopped and checked the code, sure enough it was P0301. Drove it home with the CEL on solid.

The "baseball card in spokes" noise was still present but didn't seem to be there as much as before, so I don't know if it was the exhaust or just a normal noise I'm now hearing. Also the Jeep seems to sound somewhat like an outboard motor at the tailpipe, but that could just be the colder weather we're having playing with the sound.

ANY IDEAS? I guess I'll call the dealer tomorrow and schedule an appointment as I am by no means qualified to diagnose/work on an engine.

EDIT: I talked to a friend about it and he mentioned that it could be water in the fuel. I check and I last filled up on 11/11 with 89 octane. The Jeep had sat for over two weeks with <1/2 a tank of fuel in it in my garage, but it has finally gotten cold here in Arkansas with temps dropping below freezing. If nothing else I figure a bottle of HEET and some fresh gas couldn't hurt, right? ***So I couldn't stand it and drove to Wal-mart and bought some Iso-HEET and filled the tank up with fresh gas. The Jeep ran like crap on the way there and not much better coming home. Got the flashing CEL again, still with the P0301 code. The Jeep is driving like it's a fuel issue. At one point on the way there it shuddered so bad it went through the whole drivetrain like an "I'm about to run out of gas and die" shudder that we've all felt. Fuel pump signing off maybe? Is cylinder #1 the first or last one in the fuel supply chain?
 

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Re: Jeep throwing misfire codes, need some help

Probably unrelated but, I got the flashing CEL and misfire codes after a spark plug change. Double check your coil rail and throw some dielectric grease in the plug boots.

As for loose exhaust one of these in 15 MM should help. My Napa sells them individually.

 

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Re: Jeep throwing misfire codes, need some help

Sure sounds an awful lot like what my 05 did when the precats failed and blocked the exhaust system.
:?
 

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Re: Jeep throwing misfire codes, need some help

Stinger said:
Sure sounds an awful lot like what my 05 did when the precats failed and blocked the exhaust system.
:?
X2!
 

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Re: Jeep throwing misfire codes, need some help

It seems to me sticky injectors could be dumping too much fuel into the chamber. Does not burn completely and is forced out into the exhaust system. It seems to me this could be a cause of clogged precats/cat. I would have expected the plugs to be fouled in this case, though.

You could have multiple symptoms or actual malfunctions with a single ultimate cause.
 

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Re: Jeep throwing misfire codes, need some help

cdogg44,

Sorry to say it, but sounds very similiar to when I had a cam and lifter failure. I would recommend pulling the valve cover and checking the valve lash, if you have a cam/lifter issue the rocker will be VERY loose. Turning the engine over by hand, feel the rockers for each cylinder on its compression stroke.

BTW, my Cats were damaged from running the engine with the bad cam and had to be replaced, luckily the dealer covered this under the emissions warranty after I installed a new crane cam and lifters.

GOOD LUCK!
-Jordan
 

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Re: Jeep throwing misfire codes, need some help

For me when I had the miss fire code (p0306). I changed the plugs and coil rail and tried to find exhaust leaks. All that still didn't get rid of my horrible ticking noise. It ended up being a messed up lifter and camshaft lobe.
 

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Re: Jeep throwing misfire codes, need some help

JRTOffroad said:
cdogg44,

Sorry to say it, but sounds very similiar to when I had a cam and lifter failure. I would recommend pulling the valve cover and checking the valve lash, if you have a cam/lifter issue the rocker will be VERY loose. Turning the engine over by hand, feel the rockers for each cylinder on its compression stroke.

BTW, my Cats were damaged from running the engine with the bad cam and had to be replaced, luckily the dealer covered this under the emissions warranty after I installed a new crane cam and lifters.

GOOD LUCK!
-Jordan

Having done everything else to my rig, this is exactly what I fear for my #2 cylinder misfire that I have been fighting forever and been unsuccessful in eliminating. Been honestly a little too worried to pull the cover for fear of finding this and knowing what needs to be done to fix it right. Haven't had the time or energy to go that far into it now. Done about everything else you could think of though prior to this. Hate to say it, but I'd look this way as well if I were you. Easy for me to say as I sit here on the keyboard without actually pulling mine though... Sorry man, not sure what else to tell you.

Best of Luck,

Mike
 

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Re: Jeep throwing misfire codes, need some help

JRTOffroad said:
cdogg44,

Sorry to say it, but sounds very similiar to when I had a cam and lifter failure.
-Jordan
x2

Travis_ said:
For me when I had the miss fire code (p0306). I changed the plugs and coil rail and tried to find exhaust leaks. All that still didn't get rid of my horrible ticking noise. It ended up being a messed up lifter and camshaft lobe.

x3, mine was P0305 (cylinder #5 - exhaust lifter/cam lobe shown in my avatar, LOL)
 

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Re: Jeep throwing misfire codes, need some help

my lifter looked just like yours.

as for taking the header off i didnt find it to be difficult, just tedious. i live 54mi away from auto parts place so if i needed a tool i would wait until the next day i had to go to work.
 

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Discussion Starter #18
Re: Jeep throwing misfire codes, need some help

I drove it in to the dealer yesterday to find out what's going on.

It ran absolutely horrible on the way there and at times would shudder and shake so bad you'd have thought the rearend was falling out.

When I left my house I had a P0301 code, and by the time I drove 15 miles to the dealer I had P0300, P0301, and P0305. To me that sounded like good news that it wasn't just related to one cylinder which hopefully eliminates the cam/lifter issue.

My money is on an exhaust problem. With me being the 3rd owner of the Jeep with 20,000 miles and 6 years old am I entitled to any sort of warranty on the vehicle? I didn't think so but my dad insisted I was due to the low miles but he also did mention the federal exhaust warranty. Anybody have any details?
 

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Re: Jeep throwing misfire codes, need some help

2004 had a 7/70 powertrain warranty. To get that warranty transferred to my name, I had to pay a dealer 50 bucks to attach my name to the jeep in the warranty database system back in 2006 when I bought it.

My motor replacement was covered under warranty.
 

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Re: Jeep throwing misfire codes, need some help

With multiple misfires could it be his OPDA?
 
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