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Unread 03-02-2013, 04:23 PM   #1
Maria81
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Major misfire 2000 Jeep Cherokee

My Jeep has been misfiring on 3, 5 and 6. I have changed out the spark plugs and ignition coil and yet it is still giving me the same codes. 0300 0303 0305 0306 and 0155 which is an oxygen sensor, bank 2, which has 4 sensors. I'm puzzled as what else to do. The check engine light is on and stays on while blinking the whole time. It starts okay but idles extremely rough, the Jeep shakes and you can hear it skipping. It almost sounds like it is sputtering while driving it. It has only gotten worse. Since changing the ignition coil, the start up is good and it has more power. Before that it has to be warmed up with foot on gas, bringing rpm's up or it would stall. Once warm, I could shut it off and restart it and all would be good. Now shutting it off and turning it back on does nothing. It is still the same no matter what. Fyi, I also have a block somewhere in my system that is causing the antifreeze to go out the tail pipe. I have bought the temporary liquid stuff and put it in and it has made a major difference. Barely loosing any antifreeze anymore. Any suggestions would be great. Any trick to figuring out which oxygen sensor and if a bad one could cause these problems? I'm so clueless! Please help!

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Unread 03-02-2013, 04:33 PM   #2
StevenXJ
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I'm going with the cracked head, as always.
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Unread 03-02-2013, 04:43 PM   #3
Kalali
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Replacing the head sounds like a good starting point...
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Unread 03-02-2013, 05:22 PM   #4
Maria81
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The head has already been checked and is good to go
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Unread 03-02-2013, 05:42 PM   #5
CJ7-Tim
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Simple testing will confirm if the head is cracked or not. Randomly replacing things like the head without testing and diagnosis is pointless and gets rather expensive.


Fix the O2 sensor issue. O2 sensors have a service life of about 100-150,000 miles. I suggest replacing both upstream sensors at the same time.



P0155 JEEP - O2 Sensor 2/1 Heater Performance. If you have 4 O2 sensors, Bank 2 Sensor 1 is the rear sensor on top of the manifold.

Possible causes
- Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
- Heated Oxygen Sensor (H2OS) circuit fuse
- Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground
- Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
- Faulty Engine Control Module (ECM)


If the problems continue re-index the cam sensor. Read this -> http://jeep.blackonyx.net/pdfs/jcss.pdf
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Unread 03-02-2013, 06:23 PM   #6
Maria81
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We did have the testing done on the head about 2 months ago or so and all was good. I'm gonna go ahead and change out those two O2 sensors and see what happens. I'm just puzzled because I was told that the O2 sensors could not cause these problems with my Jeep! It only has 122,000 roughly on it. I'm gonna keep my fingers crossed and hope that the O2 sensors are whats wrong with it. I fear that I may need a new engine! Thanks for the advice Tim! You have been a great help
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Unread 03-02-2013, 06:55 PM   #7
tjwalker
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The P0155 code is for the "heater circuit" for the oxygen sensor. The heater circuit is fused and the fuse is located inside of the power distribution center (black box under the hood on passenger side).

It is a mini 15 amp fuse, not sure of the exact location but somewhere in the 15-19 slot range.

It will only take a few minutes to verify each and every mini 15 amp fuse. Don't want to be chasing your tail for a blown fuse, and I've seen this fuse blow more than a few times on the XJ.
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Unread 03-02-2013, 07:15 PM   #8
Maria81
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Okay good to know. But that still does not explain what could be causing the major misfire that I am having!
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Unread 03-03-2013, 06:00 AM   #9
tjwalker
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From your description, I agree with the others and think it is very possible that you have a cracked cylinder head.

You said the head has been checked? Exactly what tests were performed? The devil is in the details here; not all tests are going to tell the story.

You said you are losing antifreeze out the tailpipe...please give us more details on what you mean by that. Note that it is not unusual to see "condensation" (water) dripping from a tailpipe that is a byproduct of the combustion process.

The fact that you were/are using/losing antifreeze is the biggest tip off to a potential head issue, as the #1 symptom of a cracked head is "unexplained coolant loss". Have you gotten under the engine with a good light and performed a comprehensive search for a leak? My opinion is that stop leak products will generally not work on a cracked 0331 cylinder head.

Below is a link to a thread with a lot of useful information on the 0331 head issue. Knowledge is power with this problem.

http://www.jeepsunlimited.com/forums...d.php?t=391831
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Unread 03-03-2013, 08:17 AM   #10
CJ7-Tim
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ALWAYS fix the lowest numbered Check Engine Light trouble codes FIRST.

Lower number trouble codes can cause bad computer sensor data, or cause the engine to run incorrectly, and additional trouble codes will be tripped due to the bad data, or the poor running.
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Unread 03-03-2013, 08:38 AM   #11
tjwalker
It's the crank sensor!
 
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Quote:
Originally Posted by CJ7-Tim View Post
ALWAYS fix the lowest numbered Check Engine Light trouble codes FIRST.

Lower number trouble codes can cause bad computer sensor data, or cause the engine to run incorrectly, and additional trouble codes will be tripped due to the bad data, or the poor running.
Agree with Tim. That's why I'd check that oxygen sensor heater fuse first thing. Another thing related to that is that I try to (if possible) pick "low hanging fruit" or codes that I can resolve easily early in the process.

One more thought. With a P0300 (random misfire), I've seen low fuel pressure cause both that code and multiple cylinder misfires.

Easy enough to check fuel pressure with a gauge on the schrader valve on the fuel rail. For a 2001, you should have 49 psi at idle, plus or minus 5 psi.
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Unread 03-03-2013, 11:37 AM   #12
buildin1XJ
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If you at one time or still do have coolant dripping from the exhaust or unexplained coolant loss, You must find the source ASAP.I have now replaced 7 0331 heads several of which had good compression on cylinders 3 and 4 and had not yet gotten bad enough to show the oil milkshake color. Sometimes I have been able to remove the oil cap with the engine running and see a stream of coolant, a coolant system pressure test with the valve cover removed is where I have had the best success in pinpointing the crack in the head as some of them had cracked so little that I was not able to visually see the crack. I do not want to sound like an alarmist I just have seen to many engines destroyed by owners ignoring coolant loss.
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Unread 03-03-2013, 08:09 PM   #13
Maria81
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My father took it and had the head checked out. I don't know what tests he had done but he said the head was okay and passed. What boogles me and the reason why I posted on here is because he tells me that a bad O2 sensor could not cause the problem I'm having but yet the part store asked me about the O2 sensor before even mentioning the code being spit out. My dad has been a mechanic for years and knows what he is doing but I feel he is not up to date anymore. He hasn't been working on cars for some time. Yes I am loosing antifreeze but my father says there is a block somewhere in the system causing it to be rerouted out the tail pipe. I have been under the car and seen no antifreeze leaks anywhere. I will try to get it somewhere to have the fuel pressure checked and will try to figure out which O2 sensor is bad. There is also no creamy whiteness to the oil. I know that is a sign of s bad or cracked head
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Unread 03-04-2013, 05:34 AM   #14
tjwalker
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Quote:
Originally Posted by Maria81 View Post
Yes I am loosing antifreeze but my father says there is a block somewhere in the system causing it to be rerouted out the tail pipe. I have been under the car and seen no antifreeze leaks anywhere. There is also no creamy whiteness to the oil. I know that is a sign of s bad or cracked head
I'm going to have to disagree with your dad. Antifreeze doesn't get re-routed out the tail pipe. But it can sure be burned out of your exhaust.

You either leak antifreeze or you burn it. You don't have a "block" somewhere. If you are using antifreeze and you can't find a leak, the odds are VERY high that you have a cracked cylinder head. It is not uncommon with the 00-01 XJ.

If this were my vehicle, I would pull the valve cover and look for a crack between cylinders 3-4. Oftentimes you can see the crack with the naked eye. Sometimes you can even see the crack through the oil filler cap with a good light; try that too, but removing the valve cover gets you a much better look. If you can't find a crack, I would have a trusted shop perform a "cylinder leakdown test". They could also perform a block test, where they sniff the coolant for the presence of hydrocarbons; it is a complementary test.

You don't always see creaminess in the oil with a cracked 0331 head. Sometimes the engine is pretty efficient at just burning it up, as well as burning up the bearings in your engine, as even small amounts of coolant mixed with your oil can toast your engine bearings.

Concentrate on that cylinder head; my money is on this as being the root cause. Take it to a different shop that can help you get to the bottom of it.
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Unread 03-04-2013, 09:34 AM   #15
LobstahJeep
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As stated 100 times above, it's probably a crack in your head. Any shop that can "check the head" is probably not Jeep smart like the people on this site. They won't know where to look and find the exact crack that hundreds of other people (myself included) have had. If your head is cracked, it may or may not make your coolant and oil mix into frothy milkshake of death. Mine did not do that at all.

In short, your head is cracked, and the coolant is washing out the cylinders, causing the misfire in the cylinders, and once it's past the cylinder, it goes in and wreaks havoc on the catalytic converter and ruins the oxygen sensors.

This is not a guess, it's a proven fact.
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