Sup guys, Well i just got my 90 hatch and i failed the emissions test, I changed the o2 sensor, but I'm clueless of what the problem could possibly be. Here are the readings:

Hc ppm: 244

Co%: 4.25

The legal limits for these two are:

Hc ppm: 183

Co%: 0.73

 

Hydrocrabon(HC) is caused by unburned fuel, or oil being present in the combustion chamber. You didnt fail by much, but i would recommend changing oil, if you havent done that. CO is also caused by a rich fuel mixture, if you change your o2 sensor, i would do a tune up on the car.

 

Yea i was thinking of doing a tune-up and changing the cat. conv.