i have a hatch runin mpfi, and i just now added an o2 sensor after 3k miles without one. so i hooked it up, and reset the computer, drove it, and i swear it made my car slower. my guage bounces from the green to red, and when its floored it goes to green, just like it should. when does the computer look at the 02 sensors input? and will it take 50 miles or so of driving for the computer to use the data, or whatever they told me at the place i bought it?

i have a hatch runin mpfi, and i just now added an o2 sensor after 3k miles without one. so i hooked it up, and reset the computer, drove it, and i swear it made my car slower. my guage bounces from the green to red, and when its floored it goes to green, just like it should. when does the computer look at the 02 sensors input? and will it take 50 miles or so of driving for the computer to use the data, or whatever they told me at the place i bought it?

When im running my XT (MPFI) it has a surging problem, that i attribute to the O2 sensor. I can drive for 200 miles and it will still surge, yet if my car is warm, and i let it idle for a few minutes it goes away and my car runs like a champ. Im going to unplug my o2 to see if that changes any.

 

I would like to hear others comments on this subject as well.

 

 

Edit: Unplugged o2 sensor and drove around tonight. Car runs much better without the surging effect that im used to. Maybe the o2 sensor is sending the computer bad data???

Maybe a switch for o2 sensor on or off? To test/perma fix?

You have something wrong with your o2 sensor, if you can unplug it and it stops. If the sensor is unplugged, teh computer will sense that, and it will substitute a value for that sensor, (Basically what it does before teh car warms up).

 

This value the computer uses, errs on the rich side, which will equate to a small power gain. However, what you are feeling is probably just the computer re-learning itself. Might get better, might not.

hrm, just like last time, i installed a sensor. it now doesnt run good unless i floor it, even after i cut the wire to the sensor, and reset the computer. reely bad