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Discussion Starter #1
140,000 miles
100,000miles new Iridium Plugs

Car sat for a week.
Went to drive today, 5min into the drive the check engine light and I could physically feel it missing. Under load and idle missing.

I didn't notice anything under the hood, no animals, oil or anything.
I OBDII scanned it came up cylinder 1 and 2 misfire.

I pulled the coil packs from 1 & 2 and swapped with 3 & 4.
Cleared the error with OBDII and restarted the car. Now 3 & 4 have pending codes for missing.

So I ordered new coils.
I pulled a plug and they still look "new" to me.

Anything else I am missing while I wait for coils?
Can I check the coils I have? The metal plates are corroded and are separating, otherwise look fine.
 

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Outback 2011 3.6R Premium
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That looks like an iridium plug and I believe double platinum plugs are the specified plugs for the 2012 H6 engine.

I suspect your coil packs are causing the problem as the fault moved when you moved the coil packs.

Seagrass
 
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2009 3.0R Outback
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492 Posts
I had to replace a couple of my coils around the same mileage. The epoxy used to pot the coil was actually cracked on one from the core laminates "rust jacking".

Hope you bought OEM coils. I tried the aftermarket route and they only lasted about a year before a couple of them started misfiring, so I replaced them with a mix of the original coils and a few used ones I bought on ebay.
 

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Discussion Starter #6
I think you are correct, but these might be the better type plug, I changed them myself.

That looks like an iridium plug and I believe double platinum plugs are the specified plugs for the 2012 H6 engine.
 

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2010 Outback 3.6R 2014 Legacy 2.5i 2003 Legacy L special edition (retired to backup)
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1,128 Posts
OP

Since the misfires followed the coils, replace them. You can get new NGK coilpacks from rockauto.com and they are significantly cheaper that OEM while actually being OEM.

misfire can be caused by

plugs
coils
injectors
air leaks
mechanical damage

I have 146K on my 2010 and I dropped in 6 new NGK laser cut Iridium plugs (141K and 6 new NGK (Subaru OEM supplier) 146k. Laser cut iridium are a suitable replacement for the H6 if you are not interested in dropping $15 to 20 per plug on the Subaru ones. Car will run just fine and return expected fuel economy.

This greatly reduced the misfires but there was a wee bit left

I then ran 3 bottled of seafoam engine treatment and 1 bottle of ATF treatment through the fuel system. It solved the misfire problem once the injectors were completely cleaned out. ATF is LOADED with dispersants and it will make short work of any deposits..



on a side note, fix that misfire asap before you have to eat a catalytic converter… at that mileage, it does not take misfiring too long to destroy your cat.
 

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2009 3.0R Outback
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You can get new NGK coilpacks from rockauto.com and they are significantly cheaper that OEM while actually being OEM.
That's still a little pricey at $75 each. If you're a gambling man like myself, this can turn out to be a better option...


Most of them will be good, if not all of them, and then you have plenty of spares.
 

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2010 Outback 3.6R 2014 Legacy 2.5i 2003 Legacy L special edition (retired to backup)
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I paid under $400 for all 6,with a discount code... but they sure did jump in price
 

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I was chasing the same issue on my wife's charger. After several rounds of shody shops and off brand parts, it's easier on your wallet and sanity to just replace all coils with OEM right away.
 
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