Are rear o2 sims required with an aftermarket x-pipe?
I was curious if rear o2 simulators are required with an aftermarket catted x-pipe. I've been trying to diagnoise a very rough idle, and lack of power on my 99 GT for a long time now. It has an aftermarket (UPR i believe) catted X-pipe. The car ran great when i bought it about a year ago. Two weeks later the Check engine light came on, and it was diagnosed to be bad o2 simulators. The shop gave me a set of 03 cobra oxygen sensors, and the car has been slowly running worse ever since. Stumbling upon accelleration, and acting like it can't get out of it's own way once it warms up.
Are o2 simulators required after installing an aftermarket X-Pipe, or are they only needed if the light comes on? Would they cause the above condition without a check engine light?