'98 Astro w/bad cat. converter

[Ressurection]

I'm in an area that doesn't smog test. Would there be any reason not to just remove the bad cat and patch in a piece of pipe? Are there any tuning issues I'd have w/ the engine?

Thanks!
P.

 

[1979jimmy350]

you will have to get a o2 simulator or you will have a constant check engine light. This is because the computer uses a o2 sensor after the cat to make sure that it is working.

 

[sweetk30]

simulator is just for offroad use. the fuel milage will go in the trash on the street. and if thay dont smog check then thay might do visuel only.


how many miles? and what is the simtoms?

 

[1979jimmy350]

the simulator should not affect the gas milage at all as long as it is only used on the rear sensor only. Only the front sensor affects the fuel delevery system the rear o2 sensor is used by the computer to make sure the cat is working by seeing a different reading then the sensor before the cat. It is only for emissions reasons.

 

[Ressurection]

The van has about 112,000 mi. I really want to hold or improve the gas milage and performance, which is why I'm considering eliminating it. The symptom is it rattles inside, and when I had an oil change the dealer told me that's the prob.
Thx.

 

[opfor2]

Just swap out the cat w/a bypass pipe. As stated on the other posts replace the O2 sensor w/a bypass also. The rear O2 sensor is so the OBDII computer can tell if the cat's are working. Is your check Eng. light on? If the Cat's are not working you should have a code stored in the OBD II computer.

Dan..

 

[CHEVY 4WD]

02 sims on the rears wont hurt anything. I have a '99 1500 and i cut my cats out and it threw a code but hasent hurt anything I havent checked it but im pretty sure I picked up a few mpg (they get cloged after 100,000 miles or so) if you have a laptop and some software(or know someone who does) you can turn them off. Im going to turn mine off when I get my new tune

 

[sled_dog]

second set of O2 sensors are just there to monitor the Cats function. O2 simulators in place of them does nothing bad. Best is to just edit them out of the program though.

 

[jhellwig]

Just poke all the catalyst out of the cat and just leave the empty box in place. Then no one will know that there is actualy no cat in there.