Engine code po304 number 4 missfire
Car is 02 wrx compleatly stock, automatic runs perfect only when ideling it skips a beat it passed smog with no problem the smog machine showed the idle betwen 709 to 730 it was not a stedy rpm it jumped all the time 709,725,715,730,710,725
I instaled new spark plugs from dealer and still the same.

Any help will be greatly apreciated
Thanks

 

Well the new spark plug was cracked figure that one out

 

I put a new spark plug in cleared the check engine light and still does it.
Whats going on here????
I also chaenged the coil!!!!

 

you most likely need to get your valves adjustid i am a subaru tech i've seen alot of that happening to early wrx's

 

I thought this are fixed you can't adjust them, do you replace the cup on top of the valve???

 

yes there is buckets on top of the valves but there are shims on top of the buckets. this is only on the 02 wrx's. for some reason the 02's are coming in alot with misfire codes. and all of them run fine a little shake at idle but all turbo subaru's do a little.anyway the valves need to be shimed they are most likely a little tight. so you should look into getting it looked at. let me know if you have anymore question's

 

Thanks it is going in the shop tomorrow will keep you posted...