5spd GT

I pulled the plugs (after it sat for a week) and all looked lean or about where I want it, but #3 pulled dark (not oil), like it was running richer than the others.

It does pop when driving around (especially under load). Codes read and I got a 41 (passenger side 02 sensor).

What are your thoughts? Would a malfunctioning 02 sensor cause this on one cylinder?

What have you guys seen?

Thanks in advance.

mjr46

swap o2 to other side and see if 91 comes up, I think I told you this before, if it does = bad 02 and no a bad o2 will affect entire bank, post pics of the plug vs another

5spd GT

I got new 02 sensors - needed them anyways.

Away right now, but 7 plugs are lean and look good, but #3 is dark (no oil).

mjr46

do a compression test and leakdown test on the cyl and compare to others, if it is good, need to determine what is on the plug, carbon? , I know you say no oil but oil can manifest as deposits, usually an ash color, but sisnce you say dark, it sounds as if it is carbon due to incomplete combustion, so do as I say, after that do a FP leakdown test which can determine if there is a leaky inj.