Will CEL from Cat hurt performance??

[03EP3Si]

Im about to install that Down pipe and Cat combo. I know this will throw a CEL. but what i dont know is if that CEL light will hurt performance of the car. and i also know about the 02 simulators. i cant get those right now so im just curious as to if the CEL from the cat will hurt the cars performance.

[andy]

i haven't noticed any loss in performance (i put on an aem cai,
comptech cat back and the cat at the same time), nor a loss in
gas mileage.
i do have a cel (you can have a dealer/odb-II scanner clear it when
it comes on), but it doesn't seem to be doing anything. someone
said it might be tweaking the a/f ratio to try to correct, but if
that were the case, i would think i would get a dirty tail pipe
and i'd see gas mileage drop. i haven't noticed either of those
to any effect.

[03EP3Si]

ok kewl man just one quick question.. is it the maintenece required light that comes on or the actual orange engine picture light? cause if its the maintenece required light then its easy to reset.. but i duno about the other one.

[andy]

it's the orange alien-object looking one. ;) (fwiw, my aunt's
ford minivan has the same light and theres was on too, heh. guess
they're running a straight pipe on that beast! ;) )

you can clear it temporarily by unplugging the battery for a few
mins, or have the dealer/a friend with a scanner do it. i've reset
it via my battery 2 or 3 times, but it always comes back on after
about 100 miles.

[03EP3Si]

kewl kewl thanks man appreciate it.

[DavidT]

Go to somebody with a OBDII scanner and pull the CEL code and post it so we know what it is. If it's really a CEL O2 sensor or cat code your car will be running in "open" loop mode and you will sooner or later suffer from bad gas mileage and poor performance, especially in the hotter weather comes around because the computer isn't getting the correct readings to adjust air/fuel correct so it just goes to open loop mode and runs one standard program in the PROM instead of closed loop where it adjusts everything according to sensor readings. Understand?

[03EP3Si]

got ittt i just gotta find someone who has access to that

[anjapower]

now an 02 simulator should avoid such problems correct? Since the CEL isn't on, the ECU should be working normally, no?

[Siman]

some guys were sellihg WOKRING 02 simulators on ClubRSX! they were like 50 bucks. basically they found out what the correct 02 reading signals looked like and fed it back through the 02 signal terminal thing a magig. Me and my brother had the very same idea with our old 2001 Spec-V ser....but we traded that for the RSX-S;)

[jandetuning]

Originally posted by DavidT
Go to somebody with a OBDII scanner and pull the CEL code and post it so we know what it is.

I'm pretty sure it is P0420. "Catalyst efficiency below threshold"

The reason it comes on after 50 to 100 miles, is that it takes three complete drive cycles for the ECU to recognize a problem with the cat.