o2 sensor? black smoke on heavy throttle in 4th..

[mark '87 930]

i went on a little trip this weekend, and on my way up to my destination, i noticed two things:
1) the car was getting HORRIBLE gas mileage.. like 8-9 mpg on the highway whereas I used to get ~25..
2) When I hammered the gas in higher gears the car was not moving, in fact was pretty much feeling like it was stalling... then i noticed in my mirror that clouds of very black smoke were coming out the muffler

When I got up there, I disconnected my o2 sensor, and everything from there forward was fine.. i hit the throttle and she pulls like she should...

So....as some of you may have read, I've very recently replaced my headers and put on a set of GHL w/heat. In doing that, I've had to take off the o2 sensor from the stock exhaust and install in the new one. I had to heat it up red for it to even budge... did I ruin it?

[serge944]

I think you answered your own question. Red hot is like, what, 1400-1600 degrees F? With heat, the voltage produced by the sensor rises - you probably cooked the internal wiring, if you didn't damage the tip.

The black smoke is an indicator that you were running very rich, but you probably already knew that.

[mark '87 930]

should i also consider replacing/cleaning my spark plugs. i'm guessing they're in pretty rough shape with all that gas?

[Por_sha911]

You can pull the plugs and see how they look. Chances are they are fouled and since they are cheap, I would go ahead and replace them after you get a new O2 in there.