Burning Through Ignition Coils

[jp7794]

Hello all. Rough day for the KJ. Sudden misfire and the check engine light comes on this afternoon. Limped it about a mile home. Scanned for codes and had P0700, P0306, and P2317. Pulled #6 coil pack and it was literally melted. Replaced coil pack and plug. Cleared codes. Issue is still present and the replacement coil pack may be bad now also as it was very hot and was cracking even after just a few seconds of testing.

Of course this happens at the worst time leaving my wife home alone with no vehicle as I travel for a week for work. It will be going to the shop tomorrow if they can fit it in. Has anyone seen this? That coil pack was too hot to hold on to for very long for a good half hour after I pulled it. Scary hot. :-(

Thanks everyone.

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[LibertyTC]

First I've ever heard of this issue. Limited to the 6th cylinder.
Something is definitely not right, & I have no idea what would cause the coil pack to melt like that.
Even with the misfire, was the valve train quiet or rattling?
Check alternator output voltage? What is it reading?
I know these coil packs fire the plug hot, but this is something else.
I'd pull # 6 plug again to inspect. Did you install ZFR6F-11G NGK and gap it at .040 inch?
Could this be a bad battery ground situation or wiring to the coil pack itself?
Ensure batt terminals are clean & tight.
What brand of coil pack did you install? Mopar coil packs are best.
Best-O luck at shop, please keep us informed.
Bill our electrical specialist, hopefully chimes in on this thread as well.

 

[jp7794]

Thanks for the reply TC. Valve train sounded okay. It sounds and feels like it is running on 5; which of course it is. I replaced the plug with the coil. It had a month old NGK plug. The coil brand is BWD as I was at the mercy of the local auto parts store. While I did not check alt. voltage, I did disconnect the negative cable to reset the PCM and the terminals are fine.

I am traveling all day today but will update this thread with the details as I can. Your emoji are my feelings exactly about this. It happened 30 minutes before the parts store closed. I moved fast and precise with my looking up the codes and finding what was wrong. Made it to the parts store just in time and thought I had gotten lucky. Lady Liberty had other ideas. This was my biggest fear when I got rid of my KL last month, and it has come to fruition way too early.

 

[Billwill]

Definitely try to obtain a Mopar part!

If that burns out it will be fun trying to find the problem!
The plug connected to that ignition coil may have gone bad and caused the failure but you have replaced that plug!

The common wires to all the coils are all Red/Orange and go to a common splice number S151...maybe a problem at that splice or the Dark Blue/Orange lead going to #6 plug may have a problem somewhere.....let's see how it goes.

You can download the 2006 Jeep KJ manuals here..section 8W has the wiring diagrams and there is a description of how to replace the coils and set the plug gaps which are pretty obvious.

Hope you carry a Fire Extinguisher with you at all times!

www.colorado4wheel.com/manuals/Jeep/KJ/

 

[jp7794]

Thanks for chiming in Bill. Shop called today and thinks it is the PCM. They are having trouble finding one and of course it will be a refurb. Total would be as much as $800 as it may need to be towed to the dealership 50 miles away to be programmed. This is a tough decision. I just had some work done to make it my daily drive again.

What do you think of their diagnosis? I really have no idea about the theory of how it gets it's spark.

Can I trust a refurb PCM? They said they might have the tools to program it but I am afraid I may be opening up a whole new can of worms with one.

Otherwise the Jeep is pretty solid and will only be used for short trips of 50 miles or less. I was hoping to get a couple more years out of it.

Any opinions would be appreciated. Should it stay or should it go?

 

[Billwill]

I would physically trace the wires going to that ignition coil for a loose connection or short to ground.

Disconnect the battery.

Disconnect the C2 connector on the PC and the connector on #6 coil.
The Dark Blue/Orange wire should now be hanging in mid air.

Measure with a Multi Meter set to Ohms that this wire has no continuity to engine/chassis at all. Make sure you do not hold meter lead ends with your bare hands as it will affect the reading.

If there is any reading at all, try trace this wire from end to end and repair any short to ground or replace the lead completely.

If this lead is faulty it may have damaged the PCM..time wil tell!

 

[tommudd]

Thanks for chiming in Bill. Shop called today and thinks it is the PCM. They are having trouble finding one and of course it will be a refurb. Total would be as much as $800 as it may need to be towed to the dealership 50 miles away to be programmed. This is a tough decision. I just had some work done to make it my daily drive again.

What do you think of their diagnosis? I really have no idea about the theory of how it gets it's spark.

Can I trust a refurb PCM? They said they might have the tools to program it but I am afraid I may be opening up a whole new can of worms with one.

Otherwise the Jeep is pretty solid and will only be used for short trips of 50 miles or less. I was hoping to get a couple more years out of it.

Any opinions would be appreciated. Should it stay or should it go?

You can buy refurbed PCMs all day for under 200 already programmed and plug and play
I've installed 8-10 of them with zero issues

 

[Billwill]

Yeah if the existing #6 Ignition Coil burns out and the wiring to the coils checks out with no shorts or breaks then worth getting a new PCM at $200.

 

[tommudd]

carcomputerexchange.com $199.00 for a KJ already preprogrammed and ready to go
they just need your VIN number to program it and send in old one
1-800-241-7104

This is where several I have done for customers and one on the 03 came from, no issues at all, simple to install yourself

If that comes down to the issue you are having

 

[jp7794]

Wow! I did not they were so readily available. And plug and play! Working lots of hours on the road but will let the shop know this is available. Thanks all!

 

[jp7794]

Update in case this happens to others. It was the PCM. It was sending constant power to the #6 coil; not a pulse.

 

[Billwill]

Great, Glad you fixed it!

At least we all learned something from this....put a meter or an oscilloscope on it!

 

[FranzKK]

Update in case this happens to others. It was the PCM. It was sending constant power to the #6 coil; not a pulse.

I just got my 2008 scanned yesterday and got the same diagnosis! Did you have success after changing the PCM and the coil and plug? I worry that wiring also could be at fault.

 

[FranzKK]

Update in case this happens to others. It was the PCM. It was sending constant power to the #6 coil; not a pulse.

How long has your replacement PCM lasted? I had this same problem and replaced the PCM last April, but now experiencing the same issue again. Shop has not had any time to look at it this week, so I will be chasing the cylinder 6 wiring to check for faults.

 

[Ksat]

Just thought I'd chime in here, South Main Auto on their youtube channel had a problem with a melted ignition coil on a Liberty and the problem turned out to be a wigged out cam sensor, which was sending erroneous signals to the PCM. This caused the PCM to trigger the coil to such an extent it was on at a nearly a continuously state. With this 3.7, and perhaps all on the KJ, the PCM doesn't require a crank signal for the engine to run and with this particular problem, the cam sensor was sending the bad signals even during KOEO, which is actually when the meltdown occurred.