I've done the searching around for answers, but I've found none. I've replaced the plugs(they were fine aswell), swaped the 4th coil pack for the 3rd and still the p0304 (misfire cylinder 4) code.
I'm running stage 2 cobb AP with up pipe, 3" exhaust w\cat, k&N filter.
I put injector cleaner in the other day and then this started, running very rough, and bogging down inbetween gears.
I'm going to get the injectors cleaned professionaly on Sun.
Has anyone else had this problem, and how did it get fixed?
Starting to frustrated, Please help

 

did you use the cleaner before or after you replaced the plugs?

 

Sorry, I should have been more clear. I put the injector cleaner in just before all this trouble happened. I'm installing a new fuel filter tomorrow and when that doesn't work I'm thinking that I'm going to spend the $85 to get the fuel injectors and valve train cleaned professionaly, to start. My next step might be the O2 sensors.
I've got 97,000 kms on the car. When I pulled the plugs, 1,3, were perfect, 2,4 were a little darker with carbon, but not bad. (they had 45,000 kms on them)
Also I switched the coil packs from #4 to #3, to see if that would make a difference, but to no avail, still the p0304 cel
How easy is it for an injector to go bad? and what is the life span of one?

 

No kidding! The same thing is happening to my 04 wrx. P0301 misfiring on cylinder 1. Car shaking roughly and the cel is blinking. No power what's so ever. I hope to get it fixed tomorrow by a performance shop...I'll let you know if I'm successful or not. Good luck to you.

 

Well, for those of you who are wondering, I changed the fuel filter, started it and no luck. then Iwent and got some Lucas upper cylinder lubricant (it's a fuel additive, in the little bottle) added it , idled the engine for about 2 min. Turned the car off for about 5-10 min, (had a sandwhich) went out and started the car again and WOW!! It idled smooth!!! took it for a drive, no problems. Reinstalled my stage 2 91 octane, all's good. Bumped it up to stage 2 93 octane (that's what I'm running) Still smooth.
I will still get the pro flush soon

 

good deal then

 

Well, I started the car after letting it sit all night, and the problem is back, but, it fixes it self when driven. I think the pro flush of the fuel system and injectors is needed. If that doesn't work then it's time to do a compression check and/or check the valves.
Waht can cause this? Can idling the car after a run cause this?

 

Just to put this thread to bed, I've fixed the misfire problem, at least for now.
To recap: changed the plugs, fuel filter, swaped the coil packs 3 for 4, used lucas oil upper cylinder lub, finaly I used sea foam in the gas tank. The problem has went away, and hasn't come back for about 3 days now.
Hopefully it's gone for good, I'm going to carry an extra can of sea foam just in case.

 

Well the problem came back, I finaly went to get a pro fuel flush. I ran great for the day, the next day, it ran like crap again. I'm running another can of sea foam through it again and it runs smooth. I'm think I'm going for a compression check and maybe have the injectors looked at.

 

3 days later the cel p0304 is on again and the car runs like crap. It's misfiring.
After adding another can of sea foam it runs fine for a while then is starts to misfire.
a compression test is in order.

How hard is it to get the injectors flow tested?

What is the potential cost of a valve adjustment ?

 

It's been days later and the problem still exists. I'v done a compression test, all cylinders are OK. I swaped the injectors from #2 to #4 and presto magic, the car popped up with an p0302 cel. That's great news! A new injector is going in tomorrow morning. Hopefully this problem will be behind me.

 

hmmm that was not what i would have guess

but they do go out

good job

 

Well I just did the injector, and the problem went away.( no more cel) I drove the car for about an hour, city and highway driving. The only problem is a low idle condition, it's around 500 rpm. Hopefully it will straighten itself up again to 750. I'm not going to load my AP stage 2 map yet, I want to see if the idle will fix itself.

 

how hard was it for you to remove the injectors? and what car do you have? I have 00RS and having the same problem. I really want to swap out the injectors to see if the code follows. But it's so hard to get to.

 

The injectors arn't that hard to remove. For the record I have a 2002 wrx