I put a new header on my LX but my o2 sensor extention was delayed in shipping, so i went ahead and put the sensor in the bung that only monitors one of the cylinders. I got the extention yesterday and pulled the rear plug out and this is what it looked like





now is that normal for being infront of the cat or only monitoring one cylinder... or is my car running rich.... i am getting low gas millage (29-30mpg) and when i swaped in the new header, the old o2 sensor was basicly rust welded in the manifold so i bought a new one... reset the computer and let it idle for 30 min with all the accessories off.... thoughts?

 

If that plug is before the cat, it looks fine. Otherwise, you may be running rich. That black stuff looks like unburnt fuel or carbon deposits.

 

Yeah, that is before cat... So if that's fine, I'll look else where for my mileage issues

Ps. As it turns out I couldn't put the o2 sensor where that plug is because the axle is in the way.... I'm gonna have to get a new bung welded in...

 

The other day I had the pipe break just before the rear suspention... I pulled the muffler today (wasn't connected anymore) and the whole back side of the car on the underside is covered in the same black ash.... Burning rich you say?