stock cat blowout

[simshahh]

after intense researching on my L and replacing most of the fuel system with no help from me running lean, I'm going to punch out the stock cats friday night. This is pretty ghetto, i know, but it will help me with solving the problem. if it does work, i will buy some new stock ones and weld them back into place. if it doesnt then i know my cats arent the problem. im going after the cats because when my truck gets to operating temp it has a odd smell....like fireworks, not normal exhaust. typically i know cats smell like eggs when they go bad, but im guessing one is just badly clogged. pretty much running out of ideas on what to do to this damn truck.

my question is this....we have O2 sensors before and after the cats, so if i punch them out, what affect will it have on the sensors reading after the cats, and what would this cause the ecm to do, as in, more fuel, less, same...??? any affect?

 

[vwjunkie53]

Rear O2s are just a "check" sensor for the OBDII system. They tell the computer if the cats are doing their job, or not. It will throw a check engine light if they aren't cleaning up the exhaust anymore.

Jason

 

[simshahh]

Rear O2s are just a "check" sensor for the OBDII system. They tell the computer if the cats are doing their job, or not. It will throw a check engine light if they aren't cleaning up the exhaust anymore.

Jason

i worried about this a little but does the same thing happen if you get a full exhaust that doesnt come with cats? also, would it throw a code if i turned off the rear sensors after i blow the cats out?

 

[vwjunkie53]

If you have a tuner like a preditor or somthing and turn the rear 02 sensors "off", it wont matter if your cats are hollow or just not there. Either way the computer wont be looking for that imput anymore because it has be re-flashed.

Jason

 

[Bootbox]

Instead of punching them out, at least clamp on some 2.5" tailpipe extenders and straight pipe them. Exhaust air doesn't flow very well through a punched out cat.