I own a 2002 gt and recently i remove both cat and waiting for the MIL to avoid service soon light. My doubt is if the engine could have a poor performance because the ECC is getting a signal from cats telling it the cats are bad.

 

its just that you took off you cats, there for you o2 sensors are going bananas, your sensors are telling you computer that you exhaust is either 2 rich or 2 poor, so you running in "safe mode" now so performance is really harmed till you tell your o2's are turned off! (mil's or tuner)

 

The check engine light does not effect performance.

 

...safe mode

 

not for me, my light was on for months before i got my mil's and it didn't affect performance...... at least not in anyway i could notice

 

Yeah, when I swapped out my midpipe my car started to run very rich. I couldn't see a whole lot of difference in performance, but I did notice my gas milage was down quite a bit. Once I put the MIL eliminators on and reset the computer it went back to normal.

 

you must not have noticed it. When I swapped my midpipe (catted) I still got the o2 sensor errors for the front two on both banks and until I replaced them, the car ran a little rough w/the CEL on

 

 

---When my car was hooked up for a few dyno runs, with the check engine light on, there was absolutely no problems with air/fuel ratio. We drive Fords, the only safe-mode is not driving it.
...safe mode ---

Just like the idiot light, this idiot can't type a reply correctly.

 

Screw A/F, you still should have dyno'd it after you got the light taken care of to solidify the fact that the CEL didn't affect performance.