if their all missfiring.. sounds like its off timing.,... which would llead me to think one of the 2 above.,... bc our cars get the signal from those 3 sensors

 

I was getting all 4 codes as well, but after reading I started noticing what comes up first.

1399 even without engine code light on
then the light will come on at idle and it sends code 0304

so I didnt have the money to replace all so I figured I would by 1 for cylinder 4 and replaced it, now at idle the engine light blinks like 6 times and goes solid and disappears, then will do it again.
as long as I dont let it idle the code will not come back do I need to replace all of them, its still popping up on 0304 before any others besides 1399.

Thanks
04 S2K 53K miles

 

this thread has been amazing in terms of learning.

However I would like your opinion guys. My '02 ap1 has the misfire codes in all 4 cylinders and random misfire. It idles rough and the light comes on sporadically when i clear the light. I DO have low compression in cylinder 2, can the low compression in that cylinder alone cause misfire in all cylinders?

 

serach "MAP wack" and its in the DIY Thread

 

just out of curiosity...

after adding the oil catch can, did the injector tips stop fouling up w/ gunk?

 

my cars doing the same!!

 

mine too, joing the club lol... i got a thread up for mine, but this is some good info, bump for useful post

 

necrobump. since i'm experiencing the same problem. was going around 35, at normal rpm and went to accelerate and the car started to hesitate. got to the light and it stumbled on the rpms but, never stalled out (though it got close)

threw 4 codes

P0302
P0304
P0300
P1399

did the map wack and only got two back which were 0304 and 1399. pulled the spark plugs and they look good so i'm going to pull the injectors and try to swap them with a friend.

 

Just a reminder to those trying to diagnose misfires at idle. Your car stores "freeze data" with the misfire code. Read that freeze data to steer you in the right direction for a fix.

Advanced readers will also do real time monitoring. If you can get a shop or friend to monitor your OBD2 port while idling you can tell a very important piece of info: your ECU is cutting fuel, or adding fuel while you idle. I did this with my laptop and a serial-to-USB adapter.

The ECU will CUT fuel if it detects unburnt fuel in the exhaust. The cutting of fuel across the board will cause a random misfire. Unburnt fuel in the exhaust is caused by a leaky exhaust valve, bad spark plugs, coil packs, spark, etc.

The ECU will ADD fuel if not enough is getting into the cylinders to sustain combustion. This may happen if your injectors are bad, fuel pump bad, bad gas, etc.

Your car will tell you what is wrong with it if you just ask. Start your diagnosis and resolution in the right direction by getting more info up front. That way you don't have to waste money on things like injectors and coilpacks that you don't need.

-read freeze data
-get real time monitoring
-get a compression check

 

I am having the same exact problem!!
My CEL is throwing all of the same codes,and I can hear it begin to misfire as soon as the car warms up. I have an 01' with 78k and am going to try replacing the coils soon. I replaced the spark plugs but that didn't help. A friend of mine had a similar issue and after he replaced two of the coils the car ran perfectly.

Keep us updated, I'm very interested to see how you fix the problem.