Cylinder four misfire

[snicker]

Ok guys, I'm at a loss. I have a misfire going on and this is whats been done to chase it so far.

Initially the car sat for 3 months waiting for a new tranny. It ran perfect prior too.

The new tranny was installed and it works great, the engine on the other hand doesn't. Always something right?

CEL cylinder four misfire.

1. I pulled the intercooler and cleaned it out
2. replaced all hose clamps for the intake system w/ new stainless clamps
3. pulled cylinder 4's spark plug and it was great.
4. cycled new quality gas through with a cylinder cleaner in it.
5. changed the oil
6. clean the maf sensor
any ideas where to start next? my timing belt, cam gears, tensioner are only a year old so they should be fine. I don't know what to look for next.

[97ScoobyL]

get all of your connectors and ground exact?

[snicker]

Which connectors? and you mean the ground on the tranny? I'm pretty sure. I should also say the it's odd that if I disconnect the battery and and reconnect to get rid of the code for a sec. Then goe hauling down a back road I get nothing. If I'm driving in traffic it idles real rough and with misfire. So, pretty much low rpm driving seems to be where it misfires.

[97ScoobyL]

Disconnecting the battery resets the PCM.

[snicker]

So I just "stared down" the engine for a while, cry inside for a bit, and guess what............. no change. I checked the grounds and they seem fine.

[97ScoobyL]

plug wire resistances?

[snicker]

This is wierd, I connected my AP to check the codes one last time and notice it wouldn't work. As I sat there my fan continued to run. I was thinking, well at least one thing works......then it hit me, the car is freakin cold! why is my fan running? Well, the test connectors aren't connected so thats not it. What is wrong with it? What would give me a misfire and have my fan running for no reason?

[snicker]

I just pulled the ancillary hoses from the balance tube (one connected to the intercooler) and it had oil in it? could this be the issue? Think if I get a catch can it'll take care of it.

[kmount]

one trick with finding missfires is to switch injectors say from 2 and 4 if the other one codes than you have a bad injector

[AmsOil]

one trick with finding missfires is to switch injectors say from 2 and 4 if the other one codes than you have a bad injector

This is a good idea, as well as switch the spark plugs (i know you said it looked fine, but weirder things have happened)

Also if it is doing it at idle and/or low rpm's, that is usually a sign of a vacuum leak. I would try and see if one of your vacuum lines, pcv/emissions valves are stuck, cracked, or anything else like this.

[snicker]

I just pulled the cyl 4 coil pack with the car running and there was no change. It might be time to get a new coil pack huh? the Spark still looks greatbut had fresh gas on it.

[snicker]

I just swapped in my friends coil pack on to cyl4 and it still misfired. Where's the pcv valve? I'll try changing it. I'm going to put new plugs in in two days. I'm don't know what else to look for. I did a head gasket check with an actual head gasket checker thing and it came up perfect. I ran 30 psi through the intake/turbo system with no leaks. What do you guys think?

[Rally OBXT]

new wires?

[kmount]

Have you tryed the injector switch? my money is on a bad injector

[drivinhard]

Did you take your pants off? That always seems to help.
Clear the code, switch the injectors and see if your misfire moves cylinders. Is your pcm responding to scan tools or your cobb tuner?

[Tedpro]

Hey I found some other forums here that have similar problems.

http://www.clubwrx.net/forums/engine-modifications/134303412-cylinder-4-misfire.html
MAF/Injectors/Tune/Low Compression

http://www.iwsti.com/forums/built-motor-discussion/144666-misfire-cylinder-4-a.html
Swap Injectors "leakdown test" / spark plugs

http://forums.nasioc.com/forums/showthread.php?t=994546&page=4
Injectors

http://forums.nasioc.com/forums/showthread.php?t=1103830
Burnt exhaust valve(excessive heat caused that to happen)

[snicker]

Anyone know where the PCV valve is?

[Jard]

Anyone know where the PCV valve is?
What year again?

WRX I assume? On an 02 - 04 WRX it should be behind and under the throttle body.

Pictures:
http://www.clubwrx.net/forums/engine-performance/168076-diy-pcv-valve-replacement-pictures.html

[Jard]

Did you install a lightweight flywheel with that new transmission?

[Tedpro]

http://www.clubwrx.net/forums/engine-performance/98574-step-step-pcv-valve-change-w-pics.html

Step by step PCV valve removal with pics.

[snicker]

I got the new pcv valve in. It was stuck shut. I had a light weight flywheel previously installed. The tune takes it into mind. The wierd thing is it didn't happen till the new transmission went on. It's a legacy b4 tranny.Would any put of that cause issues?

[Tedpro]

I remember you said yours had some residue on it , so this looks post similar.

http://www.rs25.com/forums/f13/t105508-rough-idle-cyl-4-misfire-changed-plugs-found-bigger-problem.html

And every other forum says swap injectors.

[paintbing]

Sometimes on the coil pack the little plastic retainer nub breaks off(not the clip) and the wires won't maintain a solid connection. Make sure the tab is still there (tiny black bump that holds the clip in place).