well i have a 95 cx and have had my jdm d15b in there for a while i just got the new o2 sensor hooked up and guess what my car is slowerand gets wose gas mileage? anyone ever have this happen to them? when its hooked up my cel goes away so i dont know why this would happen

 

do you haw an exhaust leak? If so that will for sure slow you down. Oeople always overlook leaks but its important to get them fixed. If no leak then im stumped. Did you have an old one in there already? Make sure you tighten it also.