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Discussion Starter #1
Now before I get shot down I have read every thread it feels like about misfires in these cars and nothing seemed to be close to what mine is doing and I have tried changing plugs, moving around coils, looking at live data and nothing is helping.

I have a 2013 wrx sti wagon with 126k miles and mostly stock besides muffler delete. the last couple months I’ve been chasing a cylinder 1 misfire that only seems to happen at around 3k rpm and I can 100 percent of the time make the cel flash if I put it in 6th and go right around the 3k rpm every time.

car doesn’t blow smoke but it smells like oil if I drive for too long on the interstate.
I randomly get the cel that says random misfire on top of the P0301 code but it’s not all the time.

I’m stumped because sometimes the car runs perfectly fine and don’t notice any issues but then the next thing I know it’s throwing the code but still doesn’t feel like power loss? Most of the time idling feels fine but rarely I can feel it idling rough. Any insight would be appreciated!
 

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Have you checked the compression, and done a leak down test? Checked for boost and vacuum leaks? Made sure the maf is clean?

Mostly stock and stock are different. Is the muff delete the ONLY thing?
 

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Completely stock besides cosmetic upgrades like radiator shroud and pulley shroud. Nothing mechanical has been changed. Have not done a compression test yet but would something like that be a constant misfire? I feel like the randomness is throwing my brain for a loop
 

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If it's consistent to one cylinder it could be. Without looking for other issues it's hard to tell. I'd start the cheapest route and rent a compression tester for 25 bucks if you don't have one. Check that cylinder compared to the others.

It wouldn't surprise me if your tgvs were shot. Mine was a consistent on cyl4 because of the tgv
 

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When you say shot do you mean like they were stuck open or closed and causing the engine to misfire because of that?
 

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Nope when I pulled the plug it looked fine to me! No excess oil no gunk on it seemed like a normal plug.
 

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They leak.
Outside of modified TGVs that have been improperly plugged, I've never heard of this happening. Did this actually happen to you?

OP - skip the compression test and go right the leakdown test. You'll be able to tell a lot more from a leakdown. Both are easy DIY at home if you have the tools.
 

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Outside of modified TGVs that have been improperly plugged, I've never heard of this happening. Did this actually happen to you?

OP - skip the compression test and go right the leakdown test. You'll be able to tell a lot more from a leakdown. Both are easy DIY at home if you have the tools.
Yes around the gaskets. You could actually see where the air was blowing out of them from the dust on the engine
 

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Yes around the gaskets. You could actually see where the air was blowing out of them from the dust on the engine
Oh OK, yes I've even had this exact failure.
 

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So this happened to me about the same mileage, for me the heads had to be resurfaced which i don't have the skill to do that, and it cost me a pretty penny, like a really really pretty penny. You will have to take it to a subaru specialist that can run diagnostics outside of a cobb unit. My error code was misfire in cylinder 4
 

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So this happened to me about the same mileage, for me the heads had to be resurfaced which i don't have the skill to do that, and it cost me a pretty penny, like a really really pretty penny. You will have to take it to a subaru specialist that can run diagnostics outside of a cobb unit. My error code was misfire in cylinder 4
Then you overheated the engine badly.
 

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Then you overheated the engine badly.
Not since i had it, I only recently overheated the engine and that was related to my radiator breaking at the top tube plastic connection, which at this time appears fixed. I purchased it with 112k miles on it, the same issue i experienced as what is being described is the same that i had at 130is-k I am now at 146k miles.
 

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I did all of these tests, swapped coils, plugs, and replaced all injectors and still wasnt fixed. Finally replaced all four coil packs and problem went away. I should have done the coil packs before injectors but swapping coils didnt move the misfire. I agree with all the suggestions just saying its a painful process of elimination. Does subaru have a weak ignition system?
 

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On the access port put the cylinder roughness as the active monitor. See how rough it is going, the usual should be about 0-2 in the roughness if it is higher then there is some potential real problems

Sent from my Nokia 6.1 using Tapatalk
 

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On the access port put the cylinder roughness as the active monitor. See how rough it is going, the usual should be about 0-2 in the roughness if it is higher then there is some potential real problems

Sent from my Nokia 6.1 using Tapatalk
Honestly "cylinder roughness" isn't a good diagnostic.
 
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