Gutting the Catalytic Converter

[Wuppy]

Will this make for worse fuel milage?
Will this cause a code and my SES light to come on?
Good idea?

[Shconer]

I don't know if your engine light on your 97 OBDII will come on but gutting your cat. wont decrease your fuel milage but will increase your fuel economy.

[lord_galathon]

No

Depends

No

Explanation;

No; It's not going to affect your gas mileage, that is unless the answer to your second question is yes.

Depends; on whether or not your model year has a CO2 or O2 sensor after the CAT.

No; Because it will obviously pollute more and this is not the legacy we want to leave our children.

[Shconer]

Yea lord is right if the PCM dosent get the corect cat. O2 readings (if it has a cat. O2) it will revert to closed loop mode and gas milage will drop drasticly.

[Wuppy]

Yeah, I do an an o2 after the cat. Any way of defeating this?

[Shconer]

You could rig up voltage regulator for like 650 mV to trick into thinking its still there.

[jtgh]

Originally Posted by Wuppy

Will this make for worse fuel milage?
Will this cause a code and my SES light to come on?
Good idea?

yes it will. CAT MONITORS they are called.
it will set P0421 and a whole bunch.
your car is OBD2 and it test the cat or Cats constantly.

whether it helps to gut or not gut depends on the car an the year.
the ECU can compensate for a reduction of exhaust back pressure. but in many cases it can not.

in many cases it is ok so long as the normal muffler is in place.
then the car can make more power and then you will unconsciencly use this extra power (jack rabbit starts etc) and bingo less MPG.

Many ECU's monitor the exhaust back pressure for the EGR monitor, if you mess this up , it will throw EGR codes too.

there are many monitors.
At any OBD2 web tech sites you can read what each do.
good luck.

[FLUFFY]

it may not be legal either
big fines here..in OZ

[jtgh]

dont make the mistake of , good cat , one inspection
and missing the next. Bad news.
( fines , and inspections more often for 5 years

heck , get one of those new High flow cats.
many are as cheap as $60.
Many countries have certified the cats such that
you can put a high flow cat in your car so long and
you do not put a cat for a smaller displacement engine.
I do not know OZ law. but these rules are common and spreading. ( bless that).
some in your area will help.
good luck.

BTW: all early Kicks , 90-95 ,gutting cat kills EGR modulator sensor> then EGR is dead, >then ECU finds this > then ECU goes to FAILSAFE forever and
gas mileage is now forever bad as is perfromance (due to retarded timing, ) says so in the FSM + FSM TB EFI suppliment. its all there and i have seen it many a time.