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Unread 12-21-2011, 02:52 PM   #1
THenderly
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Join Date: Dec 2011
Location: Columbus, Oho
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Movable Misfire, Detinated Sparkplugs

I have been dealing with a cylinder 1 misfire for some time now and 3 days ago my 2004 Grand Cherokee 4.7 V8 with 128000 Miles finally stopped firing properly.

The original problem that I had with the car was the misfire (P0301) on cylinder 1 that i could not get to go away. There were no signs of any valve ticking, popping or anything, just a misfire on startup every time i started it. I would let the engine run for a few seconds and then would give the car a little gas. This would let the engine settle out and run normally.

After a few months of owning the car, I decided to change the sparkplugs in the car. Due to my lack of understanding about the cars, a tec at Jegs sold me a set of Platinum Sparkplugs... I am really regretting this now because not only did I pay a lot more for them, this may be the cause of my engine problems.

I also found a week ago that my cruse control and cooling system was acting up. I looked on line a found that I might have a vacuum leak... sure enough I did.

About 2 days after the vacuum leak, I noticed a sight ticking noise coming from the engine on acceleration.

3 days ago, I started the car and found that the engine was running rougher than ever and would not stop running badly even after my attempts to fix the problem.

I did another incorrect thing and took the car to Crown Jeep in Dublin Ohio where I paid a 98 dollar diagnostic fee for the mentally challenged tech to tell me that the sparkplugs were causing this issue... So I changed them out with the stock champion plugs and sure enough... it wasnít the plugs. He also said "the exhaust didn't smell right". (What a great diagnosis buddy... complete Dumb A$$)

Anyway, The car has a brand new a brand new coil plug and injector in cylinder 1 (the one I believe to be the problem) and now a second new set of champion copper plugs in the car right now that are probably toast since I hear what I think is a detonation in cylinders 3 4 and 5.

According to the new place that I have taken the jeep, all coils are working and are sending spark. If you move the coils in different cylinders you can get the misfire to move to different cylinders. I watched the tec even trade out one of the coils with an extra one to see if it was just a dead coil... Itís definitely not a dead coil because he put a spark plug on each one outside the cylinder and watched each one send spark.

Compression is good (right around 150PSI on each Cylinder)

I need to know what this issue is so I can fix it. I am getting conflicting knowledge from everyone saying different things. So far these are the possible problems:

Bad Crank Position sensor
Bad Cam Position sensor
Bad PCM
"thrown" rocker arm
Bad Lifter
Thrown Cam
Vacuum Leak
Bad Sparkplugs (obviously not the issue)

When the car runs, there is NOT a constant ticking noise, only the sound of a ping every once in a while (what i believe to be a detonation) There are at least 2 misfires.

What are your thoughts? Iím at a loss...

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Unread 12-21-2011, 02:58 PM   #2
Terminator2
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If the misfires moves as the coils move it is one or possibly more of the coils that are bad. You have your answer in your post.
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Unread 12-21-2011, 03:47 PM   #3
rm2001wj
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After all that you have said, it is still not clear exactly what the problems are at this moment. If you have misfires, please give the codes. Post any other codes that you can retrieve. Is the check engine light on?

Spark plugs don't go bad as quickly as you think first set of coppers did so there is no reason to think that there is a problem with the second second set. There are multiple reasons for detonation besides spark plugs.

Yes, if the misfire moves with a coil, then the coil is bad. That does not mean that it won't produce a spark; it just means it doesn't produce a spark every time or that the spark is weak.
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Unread 12-21-2011, 03:49 PM   #4
Terminator2
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Quote:
Originally Posted by rm2001wj View Post
After all that you have said, it is still not clear exactly what the problems are at this moment. If you have misfires, please give the codes. Post any other codes that you can retrieve. Is the check engine light on?

Spark plugs don't go bad as quickly as you think first set of coppers did so there is no reason to think that there is a problem with the second second set. There are multiple reasons for detonation besides spark plugs.
He said when the tech moved the coils around the misfires moved. I think he answered his own question in that post but I too am slightly confused because his post is a little all over the place and the grammar is off in places.
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Unread 12-21-2011, 03:50 PM   #5
Terminator2
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Quote:
Originally Posted by THenderly View Post
I have been dealing with a cylinder 1 misfire for some time now and 3 days ago my 2004 Grand Cherokee 4.7 V8 with 128000 Miles finally stopped firing properly.

The original problem that I had with the car was the misfire (P0301) on cylinder 1 that i could not get to go away. There were no signs of any valve ticking, popping or anything, just a misfire on startup every time i started it. I would let the engine run for a few seconds and then would give the car a little gas. This would let the engine settle out and run normally.

After a few months of owning the car, I decided to change the sparkplugs in the car. Due to my lack of understanding about the cars, a tec at Jegs sold me a set of Platinum Sparkplugs... I am really regretting this now because not only did I pay a lot more for them, this may be the cause of my engine problems.

I also found a week ago that my cruse control and cooling system was acting up. I looked on line a found that I might have a vacuum leak... sure enough I did.

About 2 days after the vacuum leak, I noticed a sight ticking noise coming from the engine on acceleration.

3 days ago, I started the car and found that the engine was running rougher than ever and would not stop running badly even after my attempts to fix the problem.

I did another incorrect thing and took the car to Crown Jeep in Dublin Ohio where I paid a 98 dollar diagnostic fee for the mentally challenged tech to tell me that the sparkplugs were causing this issue... So I changed them out with the stock champion plugs and sure enough... it wasnít the plugs. He also said "the exhaust didn't smell right". (What a great diagnosis buddy... complete Dumb A$$)

Anyway, The car has a brand new a brand new coil plug and injector in cylinder 1 (the one I believe to be the problem) and now a second new set of champion copper plugs in the car right now that are probably toast since I hear what I think is a detonation in cylinders 3 4 and 5.

According to the new place that I have taken the jeep, all coils are working and are sending spark. If you move the coils in different cylinders you can get the misfire to move to different cylinders. I watched the tec even trade out one of the coils with an extra one to see if it was just a dead coil... Itís definitely not a dead coil because he put a spark plug on each one outside the cylinder and watched each one send spark.

Compression is good (right around 150PSI on each Cylinder)

I need to know what this issue is so I can fix it. I am getting conflicting knowledge from everyone saying different things. So far these are the possible problems:

Bad Crank Position sensor
Bad Cam Position sensor
Bad PCM
"thrown" rocker arm
Bad Lifter
Thrown Cam
Vacuum Leak
Bad Sparkplugs (obviously not the issue)

When the car runs, there is NOT a constant ticking noise, only the sound of a ping every once in a while (what i believe to be a detonation) There are at least 2 misfires.

What are your thoughts? Iím at a loss...
This!!!
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Unread 12-21-2011, 03:54 PM   #6
rm2001wj
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Terminator2, I know, and I edited my post to agree with you on that.
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Unread 12-21-2011, 05:39 PM   #7
THenderly
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I am sorry for the clarity of the post.

Hopefully this may help.

Jeep ran their diagnostic machine on the vehicle. Codes: P0301, P0300, P0303, P0304, P0305

They tested the coils in all of the shops that I have went to so far and all have said coils are okay (Crown Jeep Dealership, Import Doctors and MC auto.net). Jeep i assume would have seen a bad coil on their diagnostic tool so I highly doubt that this is it because when you swap a dead cylinders coil to another working cylinder (c2,C6,C7,C8) the cylinder continues to hold a load and work perfectly.

I’m still very confused on this one. I know the PCM retards spark when it detects a misfire. I am thinking that moving and or unplugging the coil is causing the PCM to do weird things allowing the misfire to move.

I will check the coils again. Please offer any thoughts or questions.

Thanks
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Unread 12-21-2011, 06:49 PM   #8
MeanGreenZJ
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Join Date: Apr 2011
Location: Mean Street in a desperate part of town
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You don't test COP's by putting a spark plug on each one outside the cylinder and just watch each one send spark. They need to be stress tested. Have any of these shops even bother to put a scope on the COP's to check the wave form? Has a fuel injector leakdown test been done?
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