>How old is the o2 sensor as they get old the sensor responds slower than >when new. The front one is from a 97 626 engine while the back one is the stock MX-3. Both gives the same 1sec rich 1sec lean readings. Luc St-Pierre 93 Mazda MX-3 GSR 2.5LV6 http://www.geocities.com/motorcity/downs/8175