hey guys i have an o4 sti with an accessport running stage 2 and a cobb turboback. it has only 4400 miles on it and i drive it maybe 2 or 3 times a month. a few months ago it started idling, and running rough and threw a p302 code (#2 cylinder missfire). i swapped the coil packs and plugs between cylinders 2 and 4 with no change. today i swapped injectors between 2 and 4 and took it for a drive but no change and threw another p302 cel code. my next check will be a compression check but aside from that has anyone else with an o4 sti had this problem and any suggestions? i don't drive the car really hard but i do get on it once in a while and i'm hoping it's not a cracked ringland.
thanks

 

Seems like you did all you can. Now you have to wait for the compression test. You should check out RD auto,they can help you pin point the problem

 

yeah if my compression test checks out ok i might need to go and see them since i don't know what else to change. has anyone else with an 04 sti experienced this problem? i know i can't be the only one.
thanks

 

Have you checked for any major boost leaks?

 

yes i think i checked them all. the only connection that i removed was the intercooler when i did my downpipe install. i did my compression check today and this is what i got: #1-143psi, #2-140psi, #3-140psi, and #4-142 psi. i let the car warm up for only about 10 minutes to get it up to operating temperature which is maybe why the numbers are so low. what do you guys think of these numbers?
thanks

 

When I did mine the car was really hot. But that does seem normal. You should check for leaks by smoke testing you system. Visually checking won't be much help.

 

how do i go about doing a smoke testing check?

 

Is the rough idling happening at low rpms? iirc, maybe ur front o2 sensor is going since u did all the changes listed above. -walt

 

the car runs rough at idle and up to about 3k rpms and starts to shudder and hesitate at about 5-10 psi boost.
thanks