kirby
NAXJA Forum User
- Location
- South Weber
Ok I've read the prior posts on O2 sensors and exhaust manifolds and still am not able to answer my question. My exhaust manifold had been cracked for about a year before I decided to get around to welding it up. The check engine light was on before I did that. I unplugged the battery cables to reset the light. Everything went fine for about 10 miles. The light came back on and so I had it tested. The test said I needed a new O2 sensor. I replaced the sensor that's on the downpipe from the exhaust manifold. My cherokee is a 98 with about 100,000 miles. From the mileage I figured it needed the O2 sensor anyway. The light then came on again after I reset it. What is my problem here? Do I need to change the sensor after the cat too? Since I ran it with the manifold cracked could that have sent unburned fuel to my cat and ruined that? If that's the case I didn't think that would set off the check engine light. Also I read in the manual that there is a mantenance timer to change. Is that just on the older engines because I sure couldn't find one. Last note my gas mileage sucks. I'm getting 15 to the gallon with 33's and 4.56 gears. And yes I have changed the speedo gear so it's not that.