Well I replaced the wires with new STI, and erased the codes. After a short test drive the SES light came back with the same 2 codes. P0308 (#8 Misfire) and a Pending P0314 (No Activity Detected on B1S1 O2).

I was going to swap the #8 plug with #6 plug to see if the code followed the plug. However when I pulled #6 out, the plug broke/separated where the ceramic met the metal threads. I had spare lying around from an earlier test, but when I picked it up I discovered it had also broken at the same spot. The plugs I installed I just picked up from Oreillys, NGK BKR6EGP.

Could it be the plugs or should I start looking elsewhere? Either way I need at least one new plug is the NGK BKR6EGP a decent plug?

Would a vacuum leak around the intake manifest in a single cylinder misfire?

 

" Either way I need at least one new plug is the NGK BKR6EGP a decent plug?"


A NGK #7092 sounds real familiar (See Post 3). I've never had an issue with NGK plugs or NTK O2 sensors.

 

I've had this UIM off and on so many times its not funny. Though I'm getting quite quick at taking it apart. Should I start looking into vacuum leaks, and how so? The vacuum leak concept is still something I haven't wrapped my head around yet.

 

I had similar issues after my head gasket job. I kept getting a random misfire even with new wires and plugs. Coolant is horrible on an o2 sensor and I had a bad one on the passenger side. I ended up ordering 2 new ones from rock auto (walker brand) and couldn't be happier. It resolved my problem and a lot of people swap to walker when they change them out. Don't just change out one side though, do both. You won't regret it.

 

I've been reading as much as I can on misfires. One thing caught my eye was someone mentioned something about a clean plug possibly indicate a HG leak. When I pulled the #8 plug which is misfiring I noticed that it did not have the same amount of soot/carbon when compared to others I've pulled (6 and 7).

#8 misfiring plug is on the left.

 

Do you have an inspection camera?

I would drive it around and get it up to temp, then pull #8 plug and get a camera in there. If it looks wet could be coolant. Also check after it cools to see if coolant "sweated" into the cylinder.

Im not sure, but the plug could be clean from raw gas?

 

check the injector above and see if it is clogged

 

I just replaced the orings on the injectors. If I pull them out again to test them, they should still be ok to re-use the orings? I could pull the manifold again and try one of the homegrown cleaning methods or the pre-cleaned ones on ebay.

 

Take it from me.
Jump your fuel pump relay in the fuse box under the hood and check for leaks before you plenum back on.
Don't ask me how I know.

 

I have had to pull a fuel rail probably 3 or so times right after I put in new injectors (with new o-rings) and did not re-replace the new rings, if you just changed the o rings you should be fine