Cylinder misfires or bad injectors, please post here.
 

I am trying to get a thread for people who have had these, and what was wrong or what they did to fix them. I am also trying to see just how many people have had this problem already, it seems like there are a few of us along with others who own WRX's.

I have a cylinder 4 misfire right now, and it seems to be my injector. I swapped coil packs and spark plugs between the 2 and 4 cylinders, but then still had the PO304 code for a cylinder misfire. Then today I just swapped injectors between the 2 and 4 cylinders, and my PO304 is gone now, and I have a PO302. Which is pretty much 99% that my injector has crapped out. I have an injector on order and should be in my car on Wednesday.

I know I searched on this subject quite a bit and found my problem, but it did take me a while to figure out what to diagnose or troubleshoot. So I am hoping this post might help others in the future with the same problem. It also seems Subaru dealers are having an extremely difficult time figuring this out, but its really not that difficult. So hopefully this helps if you are having a problem with this.

It's not uncommon to have problems with the yellow toped injectors. Any Subaru tech with half a brain and the SSM3 tool should be able to pinpoint it pretty quick.

I have the same problem. Injectors and coilpacks are not under the powertrain warranty either. I was charged $180 diagnostic fee and the tech had no idea what was wrong. I swapped injector 1 and 2 later that day and figured it out in 15 minutes. I get a CEL about it everything 7k miles or so. I'm wondering if a good cleaning @ Witchhunter would fix it.

just tripped a CEL last night and it's cylinder 4 misfire. I might just save myself the headache and order a new coilpack since i just replaced the plugs less than 10k miles ago. What is the part number for the coilpack and where do you order them? I hate the stealerships, but if that's the only place I can grab the part then so be it.

thanks

Doh! I just re-read the post and noticed you said INJECTOR. What's the deal with that? has anyone replaced this on their own? What's involved? and how much do they go for?

thanks again

Injectors are $80-$90. They are very easy to install. Pull the fuel pump fuse and crank the engine to get the fuel out of the lines. In the engine bay, remove the safety clip (1 screw) and the injector can be popped out. Plug your new one back in and screw the safety clip back on top.

I have a cylinder 4 misfire and the dealership said it's a bad plug and coil. I'm going to replace the plugs anyway but reading through the forums it seems that there are a lot of issues with the injectors. Has anyone had to replace thier coils? and did it fix the misfire? Or should I just replace the injector instead of the coil, and not listen to the dealership.

The dealer told me it was a bad "plug" too, of course they replaced it and it didn't fix anything. But, it might for you :)

Ok... Bringing this back to life... I've been having a cylinder 4 misfire for about 900 miles now. I replaced the spark plugs 3 days ago and I still have the same error. I guess for troubleshooting sake should I swap injectors first to see if that will fix it? What about that fuel additive "Injector cleaner" would that do anything for it? Or should I just bite the bullet and get a new injector?

Also, cylinder 4 is the drivers side rear correct?

I would swap the injectors to find out if the code does move, if it doesn't it could be a bad coil pack too ..

The code pops up randomly too from what I've noticed. It did just fine for 300 miles one time, now it went off at about 50 miles or so... Im wondering if one or the other is going bad, or if its just completely bad now...

Sounds 100% just like the problem I was having, I would swap the injector with a good one and see if the code changes to the cylinder with the possible bad injector. Since I replaced my injector I think like a week and half ago I havent had any problems. Car runs much better all the way around too. So if I had money to bet, I would say its your injector.

Oh, I have also used fuel injector system cleaner, it worked the first time for maybe a few thousand miles, but then the problem came back again. I tried the fuel injector cleaner again, and it did absolutely nothing.

I wish I would have just replaced the injector from the beginning. So I wouldnt even mess with fuel injector cleaner.

Yea, I was gonna throw some injector cleaner in there, but I guess I'll just try and switch it around and see if the code moves with it. From what I've read, it sounds like its the easiest part to swap/test. I already changed the plugs, so I'm leaning towards them not being the issue (even though I didnt check the gaps on a gapper, I did check them vs the old plugs though and it looked good there).
That rear coil pack is a PITA to get out, lol... But I did get it done, so if I gotta do it again at least I have the experience.
If it turns out to be the injector, I guess I'll have to buy a new one, where did you get yours and do you know anywhere that would be cheaper/est...

I switched the cylinder 4 injector with the one right in front of it last night and I'm idling a LOT rougher than I was previously. It hasnt thrown a CEL yet, but I'm leaning towards the injector being bad you think?
And just a quick question, was it bad not to drain the fuel first? I didnt do that :S