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2001 Outback
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24 Posts
Discussion Starter #1
So I've taken my Subie into the dealership twice for them to fix it and it's still happening. Here's the full story.

I have a 2001 2.5L OBW with 181k miles that I bought last year. I was driving on the highway about two weeks ago when all of this started to happen, one of my coolant hoses blew off and in the process I blew my headgasket and got a check engine light for a misfire on cylinder #4. So I took it into the dealership so they could fix it. They told me that someone previously had fixed the headgasket but had not properly torqued the heads down and didn't resurface them which is why it failed again :( and that the misfire was most likely because of the headgasket failure.

So the dealership fixed that and put in new spark plugs and did my timing belt and tensioner. But interesting thing here, they noticed a zip tie was on the clip for the #4 cylinder injector and that cylinder #4 had a different spark plug in comparison to all the other ones, it was rockin' a Bosch Platinum+4 when all the other ones were just regular Bosch iridiums. #4 was also where the headgasket had failed.

When I went to pick it up I noticed it was idling rougher than it had before I took it in, even with a blown headgasket. But I drove off and within about 5 minutes of driving it I got a check engine light and my car died while I was pulling up to stop, so I turned around and took it right back to the dealer.

I picked it up today and they said that the check engine light was still for a cylinder #4 misfire. So they checked to make sure the timing belt was on correctly and it was a tooth off so they readjusted that. They cleaned my injectors and swapped the ones on cylinder 2 and 4 to see if it was an injector issue or not. They tested my spark plug wires and those were fine, and they performed a leak down test on 2 and 4, #2 was 22-24% and #4 14-16%. They had driven it around and the check engine light didn't come on again for them. But guess what!? I drove it for 10 minutes and it came back on, I swung by autozone and got the codes and sure enough cylinder 4 misfire!

So I have no real idea what could be causing it. They seemed to have covered most of the bases at the dealership. I was thinking I could try a different ignition coil and maybe wires. I was also wondering if maybe using something other than iridiums? That maybe the Platinum+4 was specifically in that cylinder because it created a more powerful spark to compensate for whatever problem it was having? I don't know, any ideas?
 

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'14 Subi OBW, '18 Subi Forester
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1,766 Posts
Bit of a shot in the dark, but 2 years back I would occasionally throw a cylinder #3 misfire. After looking at the basics I finally concluded that the ignition wire to the coil socket just wasn't as clean (slight telltale sign of carbon) or fit as well as the others, even though I had little other strong evidence of a problem. Finally I just changed the coil & wire set (Subaru parts only!), and all has been well since. 8-10 years is a good run on original ignition parts.
 

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Premium Member
2001 VDC/SC One of a Kind
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14,322 Posts
It seems as though it could be a bad coil. They can fire cold, but after the heat of the engine allows for expansion, misfire.

Coil and wires will probably repair the issue.
 

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2001 Outback
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24 Posts
Discussion Starter #4
Grabbed a new Subaru ignition coil and NGK spark plug wires and the check engine light didn't come on for a couple of hours, but sure enough it popped up again! Going to take it back to the dealership tomorrow, maybe there's some weird valve problem going on that they didn't catch when they did the head gaskets. Hoping that if it costs me anything to fix it'll be heavily discounted since they have now "fixed" the problem three different times. Fingers crossed!
 

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Gallery Ninja, ,
2004 Outback "Bluebaru" & 2005 Outback XT
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5,195 Posts
Grabbed a new ignition coil and new spark plug wires and the check engine light hasn't come on yet! But the idle seems rough at times and will occasionally drop down to zero before springing back up to around 600, even had it die on me while making a U-turn. Not quite sure what to make of that.
Check for vacuum leaks, sounds like you might have some unmetered airflow. Perhaps a worn IAC sensor?
 

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2001 Outback
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24 Posts
Discussion Starter #6
Check for vacuum leaks, sounds like you might have some unmetered airflow. Perhaps a worn IAC sensor?
I like how you replied after I had edited it haha. I thought that too but I didn't really find anything besides the ill fitting resonator box on the air intake. But I tweaked it to try and make a better seal but it didn't change much. Is there supposed to be some kind of rubber gaskets between the different air intake parts? The plastic on plastic doesn't seem to be a super great design
 

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2001 Outback
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24 Posts
Discussion Starter #7
Turned out the exhaust valves on cylinder #4 were a bit tight, the dealership loosened them up and no more check engine light and no more rough idling!
 
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