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Hey guys,

   I've treated myself to a brand new 8 year old car that has its own brand new problems. :)

vitals: 2005 Outback 2.5 4eat

The car ran perfectly two days ago and then some sasquatch (me) was prodding around under the hood looking over the new car. Then the car sat for a day and today it's running as rough as an old tractor and throwing a p0302 misfire code.


I know this is a cylinder 2 misfire so I pulled plug #2 and it was in excellent condition. Plugs and wires are at LEAST 30,000kms old, maybe more. I've already ordered new NGK replacements but they aren't here yet. 

I cleaned the MAF just for fun and reset the ECU. The code cleared briefly but the rough running was still present and the p0302 came back within a minute or two. This time while watching it run with the hood up I noticed a pronounced SNAPSNAPSNAPSNAPSNAP sound coming from the area of the coil pack. The snapping noise speeds up with RPM...

Am I hearing my spark jumping from a damaged coil pack to a nearby ground? I'll watch it again in the dark later to see if sparks are evident but I'd sure like the group opinion on this one.



PS. It IS possible that I poked at, leaned on, or otherwise molested the coil pack while I was looking around at the motor the other day. 

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Sounds like a failed spark plug boot on the coil end, maybe try switching the #2 wire around and see if the miss fire follows. Also the wire may not be plugged in all the way either

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It's the wire, not the coil pack. There's a lot of amperage in there, so do this with the car off: Try pushing the wire (not boot) into the pack further. If the short still persists, glomb (Technical term) some dielectric grease into the boot and jam everything back into the pack. The dielectric will help direct the arc into the wire and not the surrounding metal. Short term fix until your new wires arrive.

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Ah ha! I was suspecting wires too because they are of unknown age... the #2 wire doesn't appear to have any continuity when I check it with my meter and it was baked onto the coil post so badly that I almost had a hernia trying to get it free. The metal part inside the coil end of the wire was unbelievably dry and appear to be partially cracked from where I had to work it off the post.

There was clearly never any dialectric grease used on it. I can't even find mine in the shop right now to try putting some on there but I think the wire is pooched anyway.

I wonder if I can get a wire or two from a local junkyard to hold me over till my already-ordered NGK set gets here. I'd hate to have to buy two sets of wires within a week or so.

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You should probably clean up the posts on your coil pack to ensure good continuity with the new wires. Little steel wool.

 

Good call. I'll do that especially once the new wires arrive. I did find my tube of dialectric grease though so I should be in OK shape tomorrow if I can locate a cheap and/or used wire to chuck on the thing temporarily.

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If you suspect any damage to the coil pack, then I would replace it. They are cheap and easy to find at a wrecking yard.

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Good news, everyone!

The wire was the culprit. Instead of risking the other brittle old wires by trying to make the misfire move to another cylinder I pull the suspect wire and put my multimeter on it. THere was ZERO continuity passing through that sucker. I checked local wrecking yards and the only ones that had any Subaru wires had them for the wrong generation (too short for this side of the motor).

At this point I didn't have much to lose so I yanked the coil end of the wire apart and the conductor was literally burned to dust. I trimmed the wire back a little to fresh conductor part and reassembled the end. Presto! 4 out of 4 cylinders again!

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Since I do youtube videos as a hobby I shot a bit of video for this plugwire repair process if anyone's interested:

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