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Cylinder misfires or bad injectors, please post here.


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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.

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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.
enough zip ties and duct tape will fix anything.
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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

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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.
enough zip ties and duct tape will fix anything.
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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.
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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?

If I pass you on the right, I'm flipping you off.
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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...
If I pass you on the right, I'm flipping you off.
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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.

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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.

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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...

If I pass you on the right, I'm flipping you off.
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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

If I pass you on the right, I'm flipping you off.
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No I don't think so ... when one of my injectors was going bad, it took like 2 weeks for the damn code to come on :)

Did you idle really rough during that time as well? Its really wierd, it was idling slightly rough before I switched the injector to the front, now it idles like it just wants to die/blow up on me. I'm thinking the code is going to get thrown here within a few days or so. Where did you get your injectors from? And stock injectors should be just fine unless I'm going to go crazy mod happy(which wont happen any time soon) correct?

If I pass you on the right, I'm flipping you off.
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yeah you can just order a new injector, they are about 95 bucks or so .. I have had all 4 go bad on my car at some point, the last time I had all 4 replaced again with a used set of STi injectors ..

 

Yeah my car would idle really rough .... You could always switch it back to see if it helps ...

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yeah you can just order a new injector, they are about 95 bucks or so .. I have had all 4 go bad on my car at some point, the last time I had all 4 replaced again with a used set of STi injectors ..

 

Yeah my car would idle really rough .... You could always switch it back to see if it helps ...

I'm trying to diagnose that as the "no joke, for sure" problem, which is why I'd rather keep it on the front, even though it idles like crap. That way when the CEL gets thrown, it should read a different cylinder misfire and I'll garuantee that's the problem. I'd rather not spend money I dont have to... lol

If I pass you on the right, I'm flipping you off.
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I just replaced the coil pack and spark plug because of a cylinder 4 misfire(it's what the dealership said was bad). I had a rough idle and a cel, Now I just have the rough idle, but it's not as bad. We'll see if the cel returns.
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My story:

 

P0301 and P0302 on idle (760rpm) from time to time.

 

1. Replaced coil - the same codes came back

2. Replaced spark plugs wire - no difference

3. Replaced all 4 spark plugs - no difference

4. Flushed injectors - only P0302 came

5. Replaced injectors - nothing for a 1.5 week. Today - P0302 back :-(

 

What is next ????

-------------------------------------------------------------------------------------

Legacy GT 2003 MT, 107K km.

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My story:

 

P0301 and P0302 on idle (760rpm) from time to time.

 

1. Replaced coil - the same codes came back

2. Replaced spark plugs wire - no difference

3. Replaced all 4 spark plugs - no difference

4. Flushed injectors - only P0302 came

5. Replaced injectors - nothing for a 1.5 week. Today - P0302 back :-(

 

What is next ????

-------------------------------------------------------------------------------------

Legacy GT 2003 MT, 107K km.

 

Check all your hoses everywhere. Make sure they are on solid and are not leaking. It could be a vacuum leak. An easy way to test for it is to have a can of starter fluid and start spraying near the hoses to see if you can find a leak. If the engine rev's while your spraying it somewhere then you have a leak or the hose isnt on properly.

 

Hopefully that'll fix you up. If not, other people may have ideas :)

If I pass you on the right, I'm flipping you off.
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2003 GT does not have turbo (unfortunately), so no turbo - no vacuum.

 

Subaru Canada suspected carbon build-up on 2-nd cylinder valve, and recommended 2-3 tanks of Sunoco 94 gas. They have additive to clean valves. Let's see how it will go. If after 2-3 tanks of 94 I will have the same problem - valves need to be replaced (no cost for me, full entended warranty)

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