Subaru Legacy 2008 2.5L Misfire

[Chickmagnet2833]

So hey just I just bought a legacy and I'm a noob. The only issue im having is when i start up the car it idles really rough and it misfires randomly. As soon as I push the gas it smoothes out and the rpms drop below 1000 and it doesn't misfire. Now I have a cheap little code scanner. And it tells me the cylinder number 3 is misfiring. However i really suck at navigating torque so idk how to look at misfires counter. I got new spark plugs for it and spark plug coils. The fuel injectors look really clean. And I hear them click repeatedly when the engine is running. No hissing noises. Clean air intake sensor. Can someone assist me here on what I should be checking next. Thanks

[Ratpowered454]

First thing, how many miles and what is the trim level/what engine is in the car?

 

First I would do a compression check in all 4 cylinders. If one of those comes back low do a leak down test, and if you need help ask here or do some youtube research. If you hear hissing in the intake/exhaust that means the valves are worn, most likely the valve guides. If you are not comfortable making that call or do not have the tools necessary to do the work, go to Subaru. At my dealership inspection maxed at $100, so if it took 1 hour or 10 hours you only pay $100. If you have the GT stop driving it unless you have a good tune or a Cobb AP so you can watch what the engine is doing. A valve leak could lead to the engine knocking, which could lead to a cracked piston and even bigger problems.

 

I had the same problem in my car, mine would misfire on idle and once it warmed up it would run ok, and improved the higher in the rev range it went. Subaru diagnosed it as a valve leak and quoted me $1800-$2200. As i'm a collage student i was unable to afford the dealership to do it so i've been doing it myself. Machine shop cost me ~$1200 for a the job,

which included inspecting the bottom end, new pistons, and reassembly along with valve job. The best thing about going through the dealership is that everything they touch is insured, so if something goes wrong they are responsible to fix it.

[Chickmagnet2833]

177 thousand miles on it. I didnt think it would be that serious but ill do a compression test and keep you updated. EJ255 2.5i. Before this i actually had to replace the valve cover gaskets bc there was oil in the sparkplug well.