straight-pipe....check engine light

[Elliot]

hey i recent had my cat and resonator chopped off and it made my check engine light go on. i went to the performance shop and they told me to get an o2 sensor extender (a little spacer thats supposed to bypass the check engine light) i just got one today and it didnt work. i know theres gotta be a way around this. anyone know?

[stepho]

Put the cat and resonator back on.
Removing them doesn't give much HP and it may be illegal.

- Stepho

[PhantomS]

Originally Posted by stepho

Put the cat and resonator back on.
Removing them doesn't give much HP and it may be illegal.

- Stepho

Agreed .... cat removal is illegal in most locales, I imagine....resonator, I dunno (am assuming op meant resonator and not muffler....and praying op didn't replace muffler with shitty sounding fartcan....I fucking hate fartcans.....)

[Elliot]

Originally Posted by stepho

Put the cat and resonator back on.
Removing them doesn't give much HP and it may be illegal.

- Stepho

actally it made a pretty big difference.

[hatchy_gt-s]

how did it make a difference
besides annoyance there is no gain from removing the res. and removing the cat only lowers fuel economy and eventually damage your engine it may 'sound' faster but rollers have proven there is no gain from removing them
that is also highly illegal in the state of CA
and why would you strait pipe a 4cyl. (thats a rhetorical question dont answer)

[Elliot]

instead of telling me what i should do.....how about just answering my question? all of your theories and all that arent gonna change my mind. of course eventually when i can afford it ill get a high flow cat but until then im stayin how it is and i just wanna know what i can do to make the check engine light go off

[stepho]

This depends on the year, but some models have two O2 sensors.
The second sensor should have a quite different value to the first sensor (ie a working cat changes the O2 level).
If the two sensors do not differ enough then the computer turns on the check light.
As far as the computer is concerned you have a broken cat - which is illegal.

Solutions:
The legal way is to put the cat back in.
The illegal way is to put a potentiometer on one of the sensor lines in order to fool the computer.
Unfortunately I can't remember which exact line.

[PhantomS]

Originally Posted by Elliot

..... i just wanna know what i can do to make the check engine light go off

OK, since you don't care about doin' the right thing, just pull the CEL bulb from your dash....there ya go, problem solved

[Elliot]

Originally Posted by PhantomS

OK, since you don't care about doin' the right thing, just pull the CEL bulb from your dash....there ya go, problem solved

nooo. the reason i want the light off is cuz i wanna know if theres any other problems. and as it is i just ignore the CEL but theres no knowing if theres any other problems unless i scan the obd2 frequently

and stepho what is a potentiometer? i got a o2 sensor extender that is supposed to make the readin differ a little bit on the second sensor but it didnt work.

[stepho]

A potentiometer is a knob that can alter the voltage (like a volume knob on the stereo or a light dimmer knob). You'll have to get a electronics guy to help you further as I'm right on the edge of what I understand with EFI (I play mostly with carburettors).
And I'm still uncomfortable with helping you bypass emissions controls.
I still think it is better to put the cat back in.
- Stepho

[Elliot]

Originally Posted by stepho

A potentiometer is a knob that can alter the voltage (like a volume knob on the stereo or a light dimmer knob). You'll have to get a electronics guy to help you further as I'm right on the edge of what I understand with EFI (I play mostly with carburettors).
And I'm still uncomfortable with helping you bypass emissions controls.
I still think it is better to put the cat back in.
- Stepho

i guess ill just ignore the CEL until i save enough for a decent cat back. shouldnt be too long anyways so yea i guess your right i best not mess with the emissions controls