No Reading From O2 Sensor, Black Smoke

October 6, 2010

I'll try to make this as short as possible for a long story. I have a '92 Paseo 1.5 5 speed. Around 200,000 miles started running rough, dead cylinder, turned out to be a total of 3 burnt exhaust valves. I replaced the burnt valves, hand lapped the rest, put new valve stem seals in, changed the oil. While I had the head off, I poured some of the Seafoam cleaner on top of the pistons as I have heard that the rings can get a lot of carbon built up on them. Car ran awesome but at the end of the 3rd day when I exited off the interstate the oil light flickered on. In 3 days it went through 3 quarts of oil. Only thing I came up with was I had used a hammer on top of the 11mm socket and lightly tapped the seals down instead of just pushing them into place by hand. So I tore it back down put in another new set of seals by hand only. Fired it back up sounds great still. But I noticed a lot of black smoke when I gave it gas. I checked the oxygen sensor and it was reading like it was fixed at zero ( 0 ). Easy enough fix, so I decided to take it to work and would pick up the sensor on my way home and replace it. It had a lot of black smoke, couldnt tell if there was blue though. But when I got home, the oil level had dropped about 1/2 a quart, and it was smelled and felt like it had gas in it. Well I replaced the oxygen sensor and guess what... its STILL FIXED AT ZERO and still has black smoke on acceleration. What am I missing? I sure hope its simple and cheap, and hoping its not the computer. btw.. no check engine light on either. It has the two wire O2 sensor, and one side shows continuity to ground, and the other just shows open, and no sign of voltage. HELP! I dont even know if I solved my oil consumption problem either.

October 8, 2010

That was quite much in oilconsumption. Do you have any visible oil leaks on the outside of the engine? If not, I guess the oil is gone in the exhaustpipe. That means that you do get oil in the cylinders somehow. It is difficult to see if it is black or blue smoke from an exhaustpipe.

I can only see 2 ways in for the oil. First through the valves and secondly from the cylinderwalls if the pistonrings are not ok.

Have you done a compression test? That might tell wich way the oil get in to the cylinders.

October 15, 2010

whilst having the head of after oil consumption i would have swapped the pistons rings for a fresh set. it sounds like oil is getting past the rings and has clogged up/damaged the o2 sensor. if it were me, id replace the piston rings and hone the cylinder bores before refitting the pistons. then see what that does to oil consumption