Check Engine Light

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Bigwill

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On my 98 Expedeition the Check Engine light came on today, when I read the code it said cylinder 5 is misfiring. I had a local mechanic change my spark plugs and wires about 9 month ago before I took a long trip. Can the wires or spark plug go bad that fast? or they did a half as job and couldn't get to the plug correctly and the wire fell out of place.
 

1997SCEBFEX

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Do you mean coil packs were changed also? Based on your estimated mileage, can certainly be the COP. A misfire can be several things, but generally connotes: 1. plug is loose, 2: COP [could] be loose, 3: combination of both... Any chance you went through water &/or washed under the hood and got water on the manifold?
 
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Bigwill

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I did not change the coil box just wire and s park plugs. Also I did go through a puddle of water.
 

toms89

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Do you mean coil packs were changed also? Based on your estimated mileage, can certainly be the COP. A misfire can be several things, but generally connotes: 1. plug is loose, 2: COP [could] be loose, 3: combination of both... Any chance you went through water &/or washed under the hood and got water on the manifold?

I believe the 4.6's do not have cops but not sure.

I did not change the coil box just wire and s park plugs. Also I did go through a puddle of water.

If water gets past the boot into the sparkplug well it can cause misfire. Pull boot and make sure #5 plug well is dry.
 

hades02

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I just posted my experience with this same problem with a #4 misfire. Like Evan said above, plug was loose. Noticed it as I was changing the plug to make sure it wasn't a bad plug. Fixed the problem.
 

BigDaddy

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I believe the 4.6's do not have cops but not sure.

My '01 has CoPs. I changed the factory ones out with Accels last year and have had them go bad intermittently on me. Drove up to West Point last Friday (a little over 750 miles round trip). Truck ran beautifully on the way up. Had lunch with a few friends and when my buddy and I went to leave to head to our hotel, it started idling rough and the check engine light came on. Drove it through the weekend, going easy on it. Got home, checked it and found #2 misfire. Swapped it out with a spare I have and it is good to go.

To the OP, I haven't seen an Expy yet with "wires" for the plugs, but I'll be honest. Mine is the oldest one I have been around.
 
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