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Cylinder 5 Misfire

Steve34k

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Jul 28, 2022
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4
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Moulton alabama
2003 tj. I6. Manual trans. Replaced plugs. Coil pack. Crank position sensor. Cam position sensor. Plugs. Injectors. Compression good. Still throws engine code. Cyl 5 missfire
 

MeanGreen86

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York, PA
In for this as I just had a cylinder 3 misfire develop. Currently throwing a new mopar coil pack at it hoping for the best.
 

P man

Keister Bunny
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Apr 11, 2021
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Washougal Wa
2003 tj. I6. Manual trans. Replaced plugs. Coil pack. Crank position sensor. Cam position sensor. Plugs. Injectors. Compression good. Still throws engine code. Cyl 5 missfire

What plugs did you install? May we assume gapped properly and oem type were used?
 

CharlesHS

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Mar 10, 2020
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Jacksonville FL, Quezon Philippines
There are a quite a few items that can cause misfires.
One item that is often missed during diagnosing is combustion chamber carbon build up on the piston top and in the valve area of the head.
You can either apply a continuous spray of MOPAR combustion chamber cleaner or Sea foam cleaner into the throttlebody for several minutes, shut off the engine and let sit for several minutes (follow application instructions on can) for quicker results or pour some Sea foam fuel injection system cleaner into the gas tank which will take longer to accomplish.
 
OP
S

Steve34k

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Joined
Jul 28, 2022
Messages
4
Location
Moulton alabama
What plugs did you install? May we assume gapped properly and oem type were used?

Ngk 2477
There are a quite a few items that can cause misfires.
One item that is often missed during diagnosing is combustion chamber carbon build up on the piston top and in the valve area of the head.
You can either apply a continuous spray of MOPAR combustion chamber cleaner or Sea foam cleaner into the throttlebody for several minutes, shut off the engine and let sit for several minutes (follow application instructions on can) for quicker results or pour some Sea foam fuel injection system cleaner into the gas tank which will take longer to accomplish.

i actually ordered mopar combustion chamber cleaner
 

Jerry Bransford

TJ Guru Moderator
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Nov 9, 2015
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Fleming Island Florida
In for this as I just had a cylinder 3 misfire develop. Currently throwing a new mopar coil pack at it hoping for the best.
There was a TSB for the #3 cylinder misfire in 2004 4.0 engines which was wrapping insulation around the #3 fuel injector. I have a 2004 and had the same misfire which is heat related and wrapping the #3 injector with the below product (specified by the TSB) cured it. It is secured around the injector with a small zip tie.

https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

Fuel Injecdtor Insulation .jpg
 

MeanGreen86

Buy once, cry once
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403
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York, PA
There was a TSB for the #3 cylinder misfire in 2004 4.0 engines which was wrapping insulation around the #3 fuel injector. I have a 2004 and had the same misfire which is heat related and wrapping the #3 injector with the below product (specified by the TSB) cured it. It is secured around the injector with a small zip tie.

https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

View attachment 346503
Ordered, thanks Jerry. What was the reason/rationale behind this TSB? seems like a weird fix.
 

Jerry Bransford

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What was the reason/rationale behind this TSB? seems like a weird fix.
Heat from the exhaust headers rises up into the fuel injector/rail area and apparently the #3 injector was especially affected in the 2004 model year 4.0. The heat causes the fuel to vaporize/bubble inside the #3 injector. Heat soak can affect any or all of the injectors in various years but the #3 was somehow especially vulnerable in 2004.
 

MeanGreen86

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York, PA
Heat from the exhaust headers rises up into the fuel injector/rail area and apparently the #3 injector was especially affected in the 2004 model year 4.0. The heat causes the fuel to vaporize/bubble inside the #3 injector. Heat soak can affect any or all of the injectors in various years but the #3 was somehow especially vulnerable in 2004.

I have the insulation kit for the rail and the injectors in my tool box. Maybe I'll install everything this weekend. Thanks. Sorry to thread jack OP
 
OP
S

Steve34k

New Member
Joined
Jul 28, 2022
Messages
4
Location
Moulton alabama
I did the mopar combustion chamber cleaner. No result. Anyone have other options. Let me say this. I have another 03 tj. Been driving for years. No issues. This is a new purchase. Was cheap. Is a nice Jeep. Been sitting since 2014
 

MeanGreen86

Buy once, cry once
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Jul 20, 2020
Messages
403
Location
York, PA
I did the mopar combustion chamber cleaner. No result. Anyone have other options. Let me say this. I have another 03 tj. Been driving for years. No issues. This is a new purchase. Was cheap. Is a nice Jeep. Been sitting since 2014

Could it be ecm based? My mopar coil pack did the trick.
 

MeanGreen86

Buy once, cry once
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Jul 20, 2020
Messages
403
Location
York, PA
The guy I bought jeep from was trying to fix it. Put. Cheap 50$ coil pack on it. It’s where I’m leaning now. Has anyone tried Ngk coil pack?

My old one was a off-brand. I saw a few mopar coil packs on ebay. I bought mine off of rockauto.
 

MoonShadowTJ

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Joined
Sep 19, 2022
Messages
14
Location
Lake Wales FL
There was a TSB for the #3 cylinder misfire in 2004 4.0 engines which was wrapping insulation around the #3 fuel injector. I have a 2004 and had the same misfire which is heat related and wrapping the #3 injector with the below product (specified by the TSB) cured it. It is secured around the injector with a small zip tie.

https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

View attachment 346503

Jerry, did you cut this “cable insulation“ in half? Looking closely at your photo there appears to be two layers, one over the other. Correct?
 

Rooscooter

TJ Guru
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Jun 7, 2020
Messages
15,630
Location
Chandler, Arizona
The guy I bought jeep from was trying to fix it. Put. Cheap 50$ coil pack on it. It’s where I’m leaning now. Has anyone tried Ngk coil pack?

I installed the NGK coil rail on a 2005 as a maintenance item at 85K a couple years ago. I wasn't having any issues but it's not caused any either.
 

MoonShadowTJ

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Joined
Sep 19, 2022
Messages
14
Location
Lake Wales FL
I can certainly make it work! When you mentioned the insulation came in a sheet I thought Amazon changed the product on its link.

I just discovered that several of my injectors are cracked as shown in the photo. Is this an issue? I‘ve found Bosch 4-hole refurbished for $109 if they need replacing. Appreciate your opinion!

00475A4C-B132-46D0-9C16-404E0A80A983.jpeg